Co-reporter:Meng Zhou, Pan Xiong, Zhaojun Jia, Ji Tan, Yan Cheng, Xuanyong Liu, Hong Cai, Yufeng Zheng
Materials Letters 2017 Volume 202(Volume 202) pp:
Publication Date(Web):1 September 2017
DOI:10.1016/j.matlet.2017.05.088
•Magnesium ions were incorporated into porous TC4 alloys by plasma immersion ion implantation method.•In vitro cells incubation indicated better cell adhesion, spreading and proliferation of Mg-implanted samples.•Mg-implanted TC4 alloys possessed better ability of apatite formation according to the SBF immersion test.In this study, three dimensional porous Ti6Al4V (TC4) with porosity (74%) and elastic modulus (0.83 ± 0.7 GPa) was manufactured by electron beam melting method. To improve the biofunction, plasma immersion ion implantation was adopted to implant magnesium ions into it. EDX and XPS spectrums confirmed the effectiveness of implantation and magnesium existed in the form of MgO at the surface. The in vitro cell experiments of Mg-implanted TC4 alloy showed enhanced cell adhesion, spreading and proliferation, attributing to the released magnesium ions. The 14 days immersion in simulated body fluid also leaded to the formation of hydroxycarbonate apatite (HCA), and the Mg-implanted TC4 alloy was more favorable for hydroxyapatite nucleation. In short, magnesium ions implantation was a desirable method to improve the in vitro cell compatibility and apatite formation ability of bio-inert TC4 alloy.Download high-res image (236KB)Download full-size image
Co-reporter:Yang Liu, Yuanhao Wu, Dong Bian, Shuang Gao, ... Jie Zhou
Acta Biomaterialia 2017 Volume 62(Volume 62) pp:
Publication Date(Web):15 October 2017
DOI:10.1016/j.actbio.2017.08.021
Novel Mg-(3.5, 6.5 wt%)Li-(0.5, 2, 4 wt%)Zn ternary alloys were developed as new kinds of biodegradable metallic materials with potential for stent application. Their mechanical properties, degradation behavior, cytocompatibility and hemocompatibility were studied. These potential biomaterials showed higher ultimate tensile strength than previously reported binary Mg-Li alloys and ternary Mg-Li-X (X = Al, Y, Ce, Sc, Mn and Ag) alloys. Among the alloys studied, the Mg-3.5Li-2Zn and Mg-6.5Li-2Zn alloys exhibited comparable corrosion resistance in Hank’s solution to pure magnesium and better corrosion resistance in a cell culture medium than pure magnesium. Corrosion products observed on the corroded surface were composed of Mg(OH)2, MgCO3 and Ca-free Mg/P inorganics and Ca/P inorganics. In vitro cytotoxicity assay revealed different behaviors of Human Umbilical Vein Endothelial Cells (HUVECs) and Human Aorta Vascular Smooth Muscle Cells (VSMCs) to material extracts. HUVECs showed increasing nitric oxide (NO) release and tolerable toxicity, whereas VSMCs exhibited limited decreasing viability with time. Platelet adhesion, hemolysis and coagulation tests of these Mg-Li-Zn alloys showed different degrees of activation behavior, in which the hemolysis of the Mg-3.5Li-2Zn alloy was lower than 5%. These results indicated the potential of the Mg-Li-Zn alloys as good candidate materials for cardiovascular stent applications.Statement of significanceMg-Li alloys are promising as absorbable metallic biomaterials, which however have not received significant attention since the low strength, controversial corrosion performance and the doubts in Li toxicity. The Mg-Li-Zn alloy in the present study revealed much improved mechanical properties higher than most reported binary Mg-Li and ternary Mg-Li-X alloys, with superior corrosion resistance in cell culture media. Surprisingly, the addition of Li and Zn showed increased nitric oxide release. The present study indicates good potential of Mg-Li-Zn alloy as absorbable cardiovascular stent material.Download high-res image (141KB)Download full-size image
Co-reporter:Yang Liu 刘洋 郑玉峰;Byron Hayes 拜伦海耶斯
Science China Materials 2017 Volume 60( Issue 5) pp:377-391
Publication Date(Web):26 April 2017
DOI:10.1007/s40843-017-9023-9
The adoption of grammatical modifier for implants or other kinds of biomaterials eventually absorbed by the body has been a long-standing confusing issue, and there are diverse terms in the large fields of research, which not only causes the difficulties when searching on the Internet, but also blurs the meaning and boundaries for researchers. Prior unification attempts at laws/standards set the basis for such research fields towards researching, labeling, marketing and instructions for use. Considering this, the typical grammatical modifiers “biodegradable”, “resorbable”, “absorbable”, along with their noun forms used in the decades of scientific research have been reviewed and explained, interdisciplinary in chemistry, ecology, materials science, biology, microbiology, medicine, and based on usage customs, laws, standards and markets. The term “biodegradable” has been not only used in biomaterials but also in ecology waste management, biomedicine and even natural environment. Meanwhile, the term “resorbable” has long been used in biological reaction (osteoclast driven bone resorption), but is inappropriate for implants that do not carry the potential to grow back into their original form. The term “absorbable” focuses more on the host metabolism to the foreign biodegradation products of the implanted material/device compared with the term “degradable/biodegradable”. Meanwhile the coherence and normalization of the term“absorbable” carried by its own in laws and standards contributes as well. In general, the authors consider the term “absorbable” to be the best grammatical modifier with respect to other adjectives which share the same inherence. A further internationally unified usage is proposed by us.关于最终被人体吸收的植入材料, 领域内文献采用的英文修饰词长期以来混乱且不同, 不仅造成文献检索困难, 同时模糊了研究人 员的研究边界. 此领域在法律法规/标准中统一用词的确定, 为领域内的科学研究、产品销售及产品使用说明奠定了基础. 我们基于化学、 生态学、材料学、生物学、微生物学和药学, 立足于使用习惯、法律、标准和市场, 对领域内使用已久的典型修饰词“生物可降解”、“再 吸收”和“可吸收”进行了讨论和解释. 总的来说, 尽管目前绝大多数修饰语实际想表达的意思相同, 作者认为“可吸收”这一英文修饰语是最 恰当的修饰词. 同时, 我们提议进一步规范和统一该领域修饰词的使用.
Co-reporter:Dong Bian, Weirui Zhou, Jiuxu Deng, Yang Liu, ... Yufeng Zheng
Acta Biomaterialia 2017 Volume 64(Volume 64) pp:
Publication Date(Web):1 December 2017
DOI:10.1016/j.actbio.2017.10.004
From the perspective of element biosafety and dietetics, the ideal alloying elements for magnesium should be those which are essential to or naturally presented in human body. Element germanium is a unique metalloid in the carbon group, chemically similar to its group neighbors, Si and Sn. It is a dietary trace element that naturally presents in human body. Physiological role of Ge is still unanswered, but it might be necessary to ensure normal functioning of the body. In present study, novel magnesium alloys with dietary trace element Ge were developed. Feasibility of those alloys to be used as orthopaedic implant applications was systematically evaluated. Mg-Ge alloys consisted of α-Mg matrix and eutectic phases (α-Mg + Mg2Ge). Mechanical properties of Mg-Ge alloys were comparable to current Mg-Ca, Mg-Zn and Mg-Sr biodegradable metals. As-rolled Mg-3Ge alloy exhibited outstanding corrosion resistance in vitro (0.02 mm/y, electrochemical) with decent corrosion rate in vivo (0.6 mm/y, in rabbit tibia). New bone could directly lay down onto the implant and grew along its surface. After 3 months, bone and implant were closely integrated, indicating well osseointegration being obtained. Generally, this is a pioneering study on the in vitro and in vivo performances of novel Mg-Ge based biodegradable metals, and will benefit the future development of this alloy system.Statement of SignificanceThe ideal alloying elements for magnesium-based biodegradable metals should be those which are essential to or naturally presented in human body. Element germanium is a unique metalloid in the carbon group. It is a dietary trace element that naturally presents in human body. In present study, feasibility of Mg-Ge alloys to be utilized as orthopedic applications was systematically investigated, mainly focusing on the microstructure, mechanical property, corrosion behavior and biocompatibility. Our findings showed that Mg-3Ge alloy exhibited superior corrosion resistance to current Mg-Ca, Mg-Zn and Mg-Sr alloys with favorable biocompatibility. This is a pioneering study on the in vitro & in vivo performances of Mg-Ge biodegradable metals, and will benefit the future development of this alloy system.Download high-res image (156KB)Download full-size image
Co-reporter:J.L. Xu, Q.F. Xiao, D.D. Mei, Y.X. Tong, Y.F. Zheng, L. Li, Z.C. Zhong
Surface and Coatings Technology 2017 Volume 309() pp:621-627
Publication Date(Web):15 January 2017
DOI:10.1016/j.surfcoat.2016.12.023
•Micro-arc oxidation coatings were successfully fabricated on sintered NdFeB magnet.•The coatings were composed of Al2O3 crystalline phase, and Fe2O3 and Nd2O3 amorphous phase.•The corrosion resistance of the coated NdFeB was enhanced by one order of magnitude.•The formation mechanism of the coatings was detailedly discussed.Alumina ceramic coatings were prepared on the sintered NdFeB magnets by micro-arc oxidation (MAO) in aluminate solution. The effects of anodic voltages on the microstructure and corrosion resistance of the coatings were investigated and the formation mechanism of the coating was also detailedly discussed. The microstructure and composition of the MAO coatings were characterized by SEM, XRD, EDS, XPS and surface roughness, respectively. The MAO coatings on NdFeB magnets were mainly composed of Al2O3 crystal phase, and Fe2O3 and Nd2O3 amorphous phase with some absorbed H2O and –OH. With increasing the voltages, the crystallinity of Al2O3 phase enhanced, while the surface roughness of the coatings also increased. At the same time, the pore sizes of MAO coatings increased, while the amount of the pores decreased. The corrosion resistance of NdFeB samples was improved due to the existence of the MAO coatings. With increasing the voltages, the corrosion resistance of the coated NdFeB samples increased first, reaching the optimum at 420 V, and then decreased. The corrosion protection efficiency of the coatings could be up to 94.3%. At the initial stage of MAO process, the compact barrier layer of NdFeB magnets was formed through the deposition of the electrolyte, which was the critical procedure for the MAO treatment of NdFeB magnets and the biggest difference from the valve metals through the conventional anodizing.
Co-reporter:Dong Bian, Weirui Zhou, Yang Liu, Nan Li, Yufeng Zheng, Zhili Sun
Acta Biomaterialia 2016 Volume 41() pp:351-360
Publication Date(Web):1 September 2016
DOI:10.1016/j.actbio.2016.05.031
Abstract
The dynamic loading in human body, along with the corrosive body fluid, presents a great challenge for the practical use of biodegradable magnesium implants. In this study, a high purity magnesium (99.99 wt.%) and two typical promising biodegradable magnesium alloys (binary Mg–1Ca and ternary Mg–2Zn–0.2Ca) were chosen as the experimental materials. Their dynamic mechanical performances were comparatively evaluated by carrying out fatigue tests in air and in simulated body fluid (SBF). The fatigue strengths of HP-Mg, Mg–1Ca and Mg–2Zn–0.2Ca were all around 90 MPa in air, however, they decreased to 52 MPa, 70 MPa and 68 MPa in SBF at 4 × 106 cycles, respectively. The fatigue cracks initiated from the microstructural defects when tested in air, but nucleated from surface corrosion pits when tested in SBF. Cyclic loading significantly increased the corrosion rates of all the experimental materials compared to that in static SBF. Moreover, based on our findings, the fatigue failure processes and interactions between material, corrosion and cyclic loading were systematically discussed.
Statement of Significance
Fatigue strength and life are vital parameters to the design of metallic implant devices. For the corrosion fatigue of biomedical magnesium alloys, we reported the corrosion fatigue behavior of AZ91D and WE43 in SBF (Acta Biomaterialia, 6 (2010) 4605–4613), and till now there is no other reports to our knowledge. We spent 3 years to finish the fatigue testing and get S-N curves for three more magnesium biomaterials, and our significant finding is that the fatigue strengths of HP-Mg, Mg–1Ca and Mg–2Zn–0.2Ca are all around 90 MPa in air but 52 MPa, 70 MPa and 68 MPa in SBF at 4 × 106 cycles, which will provide the first-hand data for the future magnesium implants design.
Co-reporter:H.F. Li, Y.F. Zheng
Acta Biomaterialia 2016 Volume 36() pp:1-20
Publication Date(Web):May 2016
DOI:10.1016/j.actbio.2016.03.047
Abstract
With a continuously increasing aging population and the improvement of living standards, large demands of biomaterials are expected for a long time to come. Further development of novel biomaterials, that are much safer and of much higher quality, in terms of both biomedical and mechanical properties, are therefore of great interest for both the research scientists and clinical surgeons. Compared with the conventional crystalline metallic counterparts, bulk metallic glasses have unique amorphous structures, and thus exhibit higher strength, lower Young’s modulus, improved wear resistance, good fatigue endurance, and excellent corrosion resistance. For this purpose, bulk metallic glasses (BMGs) have recently attracted much attention for biomedical applications. This review discusses and summarizes the recent developments and advances of bulk metallic glasses, including Ti-based, Zr-based, Fe-based, Mg-based, Zn-based, Ca-based and Sr-based alloying systems for biomedical applications. Future research directions will move towards overcoming the brittleness, increasing the glass forming ability (GFA) thus obtaining corresponding bulk metallic glasses with larger sizes, removing/reducing toxic elements, and surface modifications.
Statement of Significance
Bulk metallic glasses (BMGs), also known as amorphous alloys or liquid metals, are relative newcomers in the field of biomaterials. They have gained increasing attention during the past decades, as they exhibit an excellent combination of properties and processing capabilities desired for versatile biomedical implant applications. The present work reviewed the recent developments and advances of biomedical BMGs, including Ti-based, Zr-based, Fe-based, Mg-based, Zn-based, Ca-based and Sr-based BMG alloying systems. Besides, the critical analysis and in-depth discussion on the current status, challenge and future development of biomedical BMGs are included. The possible solution to the BMG size limitation, the brittleness of BMGs has been proposed.
Co-reporter:Xiwei Liu, Jianke Sun, Kejin Qiu, Yinghong Yang, Zhongjie Pu, Li Li, Yufeng Zheng
Journal of Alloys and Compounds 2016 Volume 664() pp:444-452
Publication Date(Web):15 April 2016
DOI:10.1016/j.jallcom.2015.10.116
•Zn–1.5Mg alloy with traces of Ca or Sr was prepared for biomedical application.•The grain size of ternary alloys became more homogeneous and smaller.•The ternary alloys exhibited much higher YS, UTS and elongation.•The corrosion rates of ternary alloys were slightly increased.•A model of the corrosion mechanism in the simulated body fluid was first discussed.Zn, a promising biodegradable material, possesses excellent biocompatibility and biodegradability, however its low strength and hardness largely limit its application in biodegradable implants. The addition of alloying elements would generally be suggested as an effective method for improving the mechanical properties. In the current study, alloying with a minor amount of Ca or Sr in Zn–1.5Mg alloy, the ternary alloys were composed of the matrix Zn and precipitated phase (Mg2Zn11 and CaZn13 for Zn–1.5Mg–0.1Ca alloy, Mg2Zn11 and SrZn13 for Zn–1.5Mg–0.1Sr alloy, respectively). Besides, the grain size of ternary alloys became more homogeneous and smaller than that of Zn–1.5Mg alloy. Meanwhile, the effect of alloying elements on the mechanical properties and corrosion behavior of Zn–1.5Mg alloy were analyzed. The results showed that the ternary alloys exhibited much higher yield strength (YS), ultimate tensile strength (UTS) and elongation than those of Zn–1.5Mg alloy. The measured corrosion rates of the ternary alloys were slightly increased due to galvanic corrosion reaction. Besides, a model of the corrosion mechanism in the simulated body fluid was discussed here based on the results of the studied alloys.
Co-reporter:P.N. Lim, R.N. Lam, Y.F. Zheng, E.S. Thian
Materials Letters 2016 Volume 172() pp:193-197
Publication Date(Web):1 June 2016
DOI:10.1016/j.matlet.2016.03.005
•Mg-1Ca/HA composites containing 5, 10 and 15 wt% of HA were formed.•Apatite and α-Mg phases were detected in the Mg-1Ca/HA composites.•Mg-1Ca/10HA composite showed better enhancement in bone differentiation markers.Mg-1Ca/HA composites were produced by blending magnesium-calcium (1 wt%) (Mg-1Ca) alloys with 5, 10 and 15 wt% of hydroxyapatite (HA). Morphology, elemental and phase composition of Mg-1Ca/HA composites were examined. Biocompatibility assessments were also performed using an indirect contact method by culturing human adipose mesenchymal stem cells (hASCs) in the extracts of Mg-1Ca alloy, Mg-1Ca/HA composites and Dulbecco's modified eagle's medium. Mg-1Ca/HA composites could promote cell proliferation and at the same time, enhanced collagen type I (COL I) and osteocalcin (OCN) expressions of hASCs. Among the Mg-1Ca/HA composites, 10 wt% of HA is the optimum amount to be added into Mg-1Ca alloy for enhanced bioactivity, thus emerging as a potential biomaterial for orthopedic fixation.
Co-reporter:Xiwei Liu, Jianke Sun, Yinghong Yang, Feiyu Zhou, Zhongjie Pu, Li Li, Yufeng Zheng
Materials Letters 2016 Volume 162() pp:242-245
Publication Date(Web):1 January 2016
DOI:10.1016/j.matlet.2015.07.151
•Zn–1Mg–0.1Sr and Zn–1Mg–0.5Sr as biodegradable metal were fabricated and evaluated.•Zn–Mg–Sr alloys showed higher YS, UTS, hardness and corrosion rate than pure Zn.•The elongation and hemolysis rates of the Zn–Mg–Sr alloys were reduced.•Zn–1Mg–0.1Sr presented a promising biodegradable implant material after rolling.The microstructure, mechanical properties, in vitro degradation behavior and hemocompatibility of novel Zn–1Mg–0.1Sr and Zn–1Mg–0.5Sr (wt%) ternary alloys were evaluated with pure Zn as control. The results indicated that Zn–Mg–Sr alloys exhibited much higher yield strength (YS), ultimate tensile strength (UTS), hardness and corrosion rate than those of pure Zn. But their elongation and hemolysis rates were reduced. Furthermore, the hot-rolled Zn–1Mg–0.1Sr alloy presented the superior mechanics performance (196.84±13.20 MPa, 300.08±6.09 MPa, 22.49±2.52%, 104.31±10.18 for YS, UTS, Elongation and hardness, respectively), appropriate corrosion rate (0.15±0.05 mm/year) and excellent hemocompatibility (hematolysis rate of 1.10±0.2% and no signs of thrombogenicity), showing a preferable candidate as the biodegradable implant material.
Co-reporter:Yang Liu, Shengmin Zheng, Nan Li, Huahu Guo, Yufeng Zheng, Jirun Peng
Materials Letters 2016 Volume 179() pp:100-103
Publication Date(Web):15 September 2016
DOI:10.1016/j.matlet.2016.05.042
•Mg(H2PO4)2 formed on WE43 when incubated in human bile.•WE43 alloy revealed a calculated corrosion rate of 0.074±0.002 mm/y in human bile.•Biodegradation mechanism of Mg based alloys in human bile was first illustrated.Mg and its alloys have been tested in both bone and blood environment, but the degradation process in human bile have not been reported yet. In this case, commercial pure Mg and WE43 alloy were investigated in human bile to see the corrosion performance as potential biliary stent materials. The results revealed the weight loss of WE43 after 60 days immersion was only 1.87%. Moreover, WE43 performed a superior corrosion resistance to pure Mg, owing to more formation of the secondary reaction product Mg(H2PO4)2. The formation of H2PO4− instead of PO43− may be due to the fact that the compositions in the bile can prevent the formation of PO43− as it is the main composition of gallstone. The much slower corrosion rate of the WE43 alloy in human bile indicated that it may be good candidates as biliary stent materials.
Co-reporter:C. Wang, H.T. Yang, X. Li, Y.F. Zheng
Journal of Materials Science & Technology 2016 Volume 32(Issue 9) pp:909-918
Publication Date(Web):September 2016
DOI:10.1016/j.jmst.2016.06.003
In this work, three widely used commercial Zn alloys (ZA4-1, ZA4-3, ZA6-1) were purchased and prepared by hot extrusion at 200 °C. The microstructure, mechanical properties, corrosion behaviors, biocompatibility and hemocompatibility of Zn alloys were studied with pure Zn as control. Commercial Zn alloys demonstrated increased strength and superb elongation compared with pure Zn. Accelerated corrosion rates and uniform corrosion morphologies were observed in terms of commercial Zn alloys due to galvanic effects between Zn matrix and α-Al phases. 100% extracts of ZA4-1 and ZA6-1 alloys showed mild cytotoxicity while 50% extracts of all samples displayed good biocompatibility. Retardant cell cycle and inhibited stress fibers expression were observed induced by high concentration of Zn2+ releasing during corrosion. The hemolysis ratios of Zn alloys were lower than 1% while the adhered platelets showed slightly activated morphologies. In general, commercial Zn alloys possess promising mechanical properties, appropriate corrosion rates, significantly improved biocompatibility and good hemocompatibility in comparison to pure Zn. It is feasible to develop biodegradable metals based on commercial Zn alloys.
Co-reporter:Tao Huang, Yan Cheng, Yufeng Zheng
Colloids and Surfaces B: Biointerfaces 2016 Volume 142() pp:20-29
Publication Date(Web):1 June 2016
DOI:10.1016/j.colsurfb.2016.01.065
•Ag ion implanted pure iron was prepared by MEVVA.•Faster and much more uniform corrosion was observed on Ag ion implanted pure iron.•Corrosion mechanism of Ag ion implanted pure iron was assumed and illustrated.•Ag ion implanted pure iron exhibited good in vitro biocompatibility.Pure iron has been verified as a promising biodegradable metal for absorbable cardiovascular stent usage. However, the degradation rate of pure iron is too slow. To accelerate the degradation of the surface of pure iron, silver ions were implanted into pure iron by metal vapor vacuum arc (MEVVA) source at an extracted voltage of 40 keV. The implanted influence was up to 2 × 1017 ions/cm2. The composition and depth profiles, corrosion behavior and biocompatibility of Ag ion implanted pure iron were investigated. The implantation depths of Ag was around 60 nm. The element Ag existed as Ag2O in the outermost layer, then gradually transited to metal atoms in zero valent state with depth increase. The implantation of Ag ions accelerated the corrosion rate of pure iron matrix, and exhibited much more uniform corrosion behavior. For cytotoxicity assessment, the implantation of Ag ions slightly decreased the viability of all kinds of cell lines used in these tests. The hemolysis rate of Ag ion implanted pure iron was lower than 2%, which was acceptable, whereas the platelet adhesion tests indicated the implantation of Ag ions might increase the risk of thrombosis.
Co-reporter:Tao Huang;Jian Cheng;Dong Bian
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2016 Volume 104( Issue 2) pp:225-240
Publication Date(Web):
DOI:10.1002/jbm.b.33389
Abstract
In this study, Fe–Ag and Fe–Au composites were fabricated by powder metallurgy using spark plasma sintering. Their microstructures, mechanical properties, and biocorrosion behavior were investigated by using optical microscopy, X-ray diffraction, environment scanning electronic microscopy, compressive test, electrochemical measurements, and immersion tests. Microstructure characterization indicated that the as-sintered iron-based materials obtained much finer grains than that of as-cast pure iron. Phase analysis showed that the Fe–Ag composites were composed of α-Fe and pure Ag phases, and Fe–Au composites consisted of α-Fe and Au phases. Compressive test showed that the improved mechanical strengths were obtained in as-sintered iron-based materials, among which the Fe-5 wt %Ag exhibited the best mechanical properties. The electrochemical and immersion tests revealed that the addition of Ag and Au could increase the corrosion rate of the iron matrix and change the corrosion mode into more uniform one. Based on the results of cytotoxicity evaluation, it was found that all the experimental material extracts performed no significant toxicity on the L-929 cells and EA. hy-926 cells, whereas a considerable inhibition on the proliferation of vascular smooth muscle cells was observed. The hemocompatibility tests showed that the hemolysis of all the experimental materials was within the range of 5%, which is the criteria value of biomaterials with good hemocomaptibility. The amount of platelet adhered on the surface of as-sintered iron-based materials was lower than that of as-cast pure iron, and the morphology of platelets kept smoothly spherical on the surface of all the experimental materials. © 2015 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 104B: 225–240, 2016.
Co-reporter:Guanping He, Yuanhao Wu, Yu Zhang, Ye Zhu, Yang Liu, Nan Li, Mei Li, Guan Zheng, Baohua He, Qingshui Yin, Yufeng Zheng and Chuanbin Mao
Journal of Materials Chemistry A 2015 vol. 3(Issue 32) pp:6676-6689
Publication Date(Web):27 Jul 2015
DOI:10.1039/C5TB01319D
Most of the magnesium (Mg) alloys possess excellent biocompatibility, mechanical properties and biodegradability in orthopedic applications. However, these alloys may suffer from bacterial infections due to their insufficient antibacterial capability. In order to reduce the post-surgical infections, a series of biocompatible Mg–1Ca–0.5Sr–xZn (x = 0, 2, 4, 6) alloys were fabricated with the addition of antibacterial Zn with variable contents and evaluated in terms of their biocompatibility and antibacterial properties. The in vitro corrosion study showed that Mg–1Ca–0.5Sr–6Zn alloys exhibited a higher hydrogen evolution volume after 100 h immersion and resulted in a higher pH value of the immersion solution. Our work indicated that Zn-containing Mg alloys exhibited good biocompatibility with high cell viability. The antibacterial studies reveal that the number of bacteria adhered on all of these Mg alloy samples diminished remarkably compared to the Ti–6Al–4V control group. We also found that the proliferation of the bacteria was inhibited by these Mg alloy extracts. Among the prepared alloys, the Mg–1Ca–0.5Sr–6Zn alloy not only exhibited a strong antibacterial effect, but also promoted the proliferation of MC3T3-E1 osteoblasts, suggesting that it is a promising alloy with both good antibacterial properties and good biocompatibility for use as an orthopedic implant.
Co-reporter:Elmar Willbold, Xuenan Gu, Devon Albert, Katharina Kalla, Katharina Bobe, Maria Brauneis, Carla Janning, Jens Nellesen, Wolfgang Czayka, Wolfgang Tillmann, Yufeng Zheng, Frank Witte
Acta Biomaterialia 2015 Volume 11() pp:554-562
Publication Date(Web):1 January 2015
DOI:10.1016/j.actbio.2014.09.041
Abstract
Rare earth elements are promising alloying element candidates for magnesium alloys used as biodegradable devices in biomedical applications. Rare earth elements have significant effects on the high temperature strength as well as the creep resistance of alloys and they improve magnesium corrosion resistance. We focused on lanthanum, neodymium and cerium to produce magnesium alloys with commonly used rare earth element concentrations. We showed that low concentrations of rare earth elements do not promote bone growth inside a 750 μm broad area around the implant. However, increased bone growth was observed at a greater distance from the degrading alloys. Clinically and histologically, the alloys and their corrosion products caused no systematic or local cytotoxicological effects. Using microtomography and in vitro experiments, we could show that the magnesium–rare earth element alloys showed low corrosion rates, both in in vitro and in vivo. The lanthanum- and cerium-containing alloys degraded at comparable rates, whereas the neodymium-containing alloy showed the lowest corrosion rates.
Co-reporter:K.J. Qiu, Y. Liu, F.Y. Zhou, B.L. Wang, L. Li, Y.F. Zheng, Y.H. Liu
Acta Biomaterialia 2015 Volume 15() pp:254-265
Publication Date(Web):15 March 2015
DOI:10.1016/j.actbio.2015.01.009
Abstract
In this study, the microstructure, mechanical properties, castability, electrochemical behaviors, cytotoxicity and hemocompatibility of Ti–Bi alloys with pure Ti as control were systematically investigated to assess their potential applications in the dental field. The experimental results showed that, except for the Ti–20Bi alloy, the microstructure of all other Ti–Bi alloys exhibit single α-Ti phase, while Ti–20Bi alloy is consisted of mainly α-Ti phase and a small amount of BiTi2 and BiTi3 phases. The tensile strength, hardness and wear resistance of Ti–Bi alloys were demonstrated to be improved monotonically with the increase of Bi content. The castability test showed that Ti–2Bi alloy increased the castability of pure Ti by 11.7%. The studied Ti–Bi alloys showed better corrosion resistance than pure Ti in both AS (artificial saliva) and ASFL (AS containing 0.2% NaF and 0.3% lactic acid) solutions. The concentrations of both Ti ion and Bi ion released from Ti–Bi alloys are extremely low in AS, ASF (AS containing 0.2% NaF) and ASL (AS containing 0.3% lactic acid) solutions. However, in ASFL solution, a large number of Ti and Bi ions are released. In addition, Ti–Bi alloys produced no significant deleterious effect to L929 cells and MG63 cells, similar to pure Ti, indicating a good in vitro biocompatibility. Besides, both L929 and MG63 cells perform excellent cell adhesion ability on Ti–Bi alloys. The hemolysis test exhibited that Ti–Bi alloys have an ultra-low hemolysis percentage below 1% and are considered nonhemolytic. To sum up, the Ti–2Bi alloy exhibits the optimal comprehensive performance and has great potential for dental applications.
Co-reporter:J.L. Xu, L.Z. Bao, A.H. Liu, X.F. Jin, J.M. Luo, Z.C. Zhong, Y.F. Zheng
Journal of Alloys and Compounds 2015 Volume 645() pp:137-142
Publication Date(Web):5 October 2015
DOI:10.1016/j.jallcom.2015.05.006
•Biomedical porous NiTi alloys were successfully prepared by microwave sintering.•The pore sizes were ranged from 97 μm to 294 μm at the same porosity of ∼50%.•The compressive strength and the elastic modulus were suitable to the bone implantation.•The mechanical properties presented “S” type variation tendency with the pore sizes.•Partial shape memory effect and superelasticity were observed for all pore size levels.Biomedical porous NiTi alloys with tailored pore sizes at the same porosity levels (∼50%) were prepared by microwave sintering technique and space holder method. The effects of pore sizes on the microstructure, macrohardness, compressive strength, elastic modulus, superelasticity and corrosion resistance of the porous NiTi alloys were investigated. The results showed that the porosities of the porous NiTi alloys mainly depended on the weight ratio of the NH4HCO3 space holder agents, while the pore sizes mainly depended on the particle sizes of the space holder agents. The porous NiTi alloys mainly consisted of the predominant NiTi phase and the secondary phases Ti2Ni and Ni3Ti. With increasing the pore sizes of the porous NiTi alloys, the Ti2Ni phase and Ni3Ti phase increased, while the NiTi phase decreased. The hardness, compressive strength and elastic modulus of the porous NiTi alloys presented “S” type variation tendency with the pore sizes, respectively. The superelasticity of the porous NiTi alloys could reach ∼4% under the pre-strain of 5% as the pore sizes smaller than 294 μm. Moreover, partial shape memory effect was observed for all pore size levels under the experiment conditions. The increase of the pore sizes had adverse effects on the corrosion resistance of the porous NiTi alloys in Hank’s solution.
Co-reporter:Xiwei Liu, Jianke Sun, Yinghong Yang, Zhongjie Pu, Yufeng Zheng
Materials Letters 2015 Volume 161() pp:53-56
Publication Date(Web):15 December 2015
DOI:10.1016/j.matlet.2015.06.107
•In vitro investigation of ultra-pure Zn and its mini-tube was evaluated with the high-pure Mg and its mini-tube as controls.•Compared to high-pure Mg, ultra-pure Zn had close mechanical properties and cytotoxicity, but it displayed lower corrosion rate and hematolysis rate.•In comparison with plates, the tubes showed higher corrosion rate and hemocompatibility.•The ultra-pure Zn mini-tubes might be considered as a potential bioabsorbable stent material.In the study, the mechanical properties, degradation behavior and in vitro biocompatibility of an ultra-pure Zn and its mini-tube were evaluated with the high-pure Mg and its mini-tube as controls. Compared with high-pure Mg, ultra-pure Zn had close mechanical properties and cytotoxicity, but it indicated lower corrosion rate (0.011 mm/y) than pure Mg in Hank’s solution. Meanwhile, the hematolysis rate (1.00%) was lower than 5%, which means that Zn has no significant destructive effect on erythrocyte. Furthermore, compared with plate specimens, the tube specimens showed higher corrosion rate (Zn ~0.028 to 0.037 mm/y and Mg ~0.61 to 0.73 mm/y, respectively) and hemocompatibility (Zn ~1.19% and Mg ~9.50%, respectively). In conclusion, the ultra-pure Zn mini-tubes might be considered as a potential bioabsorbable stent material.
Co-reporter:J.L. Xu, L.Z. Bao, A.H. Liu, X.J. Jin, Y.X. Tong, J.M. Luo, Z.C. Zhong, Y.F. Zheng
Materials Science and Engineering: C 2015 Volume 46() pp:387-393
Publication Date(Web):1 January 2015
DOI:10.1016/j.msec.2014.10.053
•Porous NiTi alloys were successfully fabricated by microwave sintering for biomedical applications.•The porosity was in the range of 22–62% with the corresponding pore size of 26–178 μm.•The compressive strength, bending strength and the elastic modulus were suitable to the bone implantation.•Partial shape memory effect and superelasticity were observed for all porosity levels.•The superelasticity of the trained porous NiTi alloys could reach up to 4.7% at the pre-strain of 5%.Porous NiTi alloys were prepared by microwave sintering using ammonium hydrogen carbonate (NH4HCO3) as the space holder agent to adjust the porosity in the range of 22–62%. The effects of porosities on the microstructure, hardness, compressive strength, bending strength, elastic modulus, phase transformation temperature and superelasticity of the porous NiTi alloys were investigated. The results showed that the porosities and average pore sizes of the porous NiTi alloys increased with increasing the contents of NH4HCO3. The porous NiTi alloys consisted of nearly single NiTi phase, with a very small amount of two secondary phases (Ni3Ti, NiTi2) when the porosities are lower than 50%. The amount of Ni3Ti and NiTi2 phases increased with further increasing of the porosity proportion. The porosities had few effects on the phase transformation temperatures of the porous NiTi alloys. By increasing the porosities, all of the hardness, compressive strength, elastic modulus, bending strength and superelasticity of the porous NiTi alloys decreased. However, the compressive strength and bending strength were higher or close to those of natural bone and the elastic modulus was close to the natural bone. The superelastic recovery strain of the trained porous NiTi alloys could reach between 3.1 and 4.7% at the pre-strain of 5%, even if the porosity was up to 62%. Moreover, partial shape memory effect was observed for all porosity levels under the experiment conditions. Therefore, the microwave sintered porous NiTi alloys could be a promising candidate for bone implant.
Co-reporter:Yang Liu, Dong Bian, Yuanhao Wu, Nan Li, Kejin Qiu, Yufeng Zheng, Yong Han
Colloids and Surfaces B: Biointerfaces 2015 Volume 133() pp:99-107
Publication Date(Web):1 September 2015
DOI:10.1016/j.colsurfb.2015.05.050
•Surface morphology changes were observed after ion implantation by MEVVA.•Y ion implantation revealed good biocompatibility.•Existence of Mg/Ca-deficient Y2O3 layer led to protection after Y implantation.•Two different mechanisms are illustrated and discussed.•Give instruction for further study of ion implantation for biodegradable Mg alloys.Mg–1Ca samples were implanted with biocompatible alloy ions Ag, Fe and Y respectively with a dose of 2 × 1017 ions cm−2 by metal vapor vacuum arc technique (MEVVA). The surface morphologies and surface chemistry were investigated by SEM, AES and XPS. Surface changes were observed after all three kinds of elemental ion implantation. The results revealed that the modified layer was composed of two sublayers, including an outer oxidized layer with mixture of oxides and an inner implanted layer, after Ag and Fe ion implantation. Y ion implantation induced an Mg/Ca-deficient outer oxidized layer and the distribution of Y along with depth was more homogeneous. Both electrochemical test and immersion test revealed accelerated corrosion rate of Ag-implanted Mg–1Ca and Fe-implanted Mg–1Ca, whereas Y ion implantation showed a short period of protection since enhanced corrosion resistance was obtained by electrochemical test, but accelerated corrosion rate was found by long period immersion test. Indirect cytotoxicity assay indicated good cytocompatibility of Y-implanted Mg–1Ca. Moreover, the corresponding corrosion mechanisms involving implanting ions into magnesium alloys were proposed, which might provide guidance for further application of plasma ion implantation to biodegradable Mg alloys.
Co-reporter:J. Cheng, T. Huang, Y.F. Zheng
Materials Science and Engineering: C 2015 Volume 48() pp:679-687
Publication Date(Web):1 March 2015
DOI:10.1016/j.msec.2014.12.053
•Patterned Au disc array films were deposited on the surface of pure iron.•The corrosion current density was 4 times larger than that of the uncoated one.•The corrosion mode turned into macroscopically uniform corrosion.•Provided a new approach to actively control the degradation mode and ratePure iron has been proven to be a potential biodegradable metal, but its degradation rate was too slow. To accelerate its biodegradation, micro-patterned Au disc films were deposited on the surface of pure iron by vacuum sputtering. The influence of Au disc films on the degradation of pure iron matrix in vitro was investigated in the present study. Electrochemical measurement results indicated that the corrosion current density of pure iron coated with micro-patterned Au disc films in Hank's solution was 4 times larger than that of the uncoated one, while the difference between the influences of micro-patterned Au discs with different diameters on the corrosion rate of pure iron was insignificant. Immersion test indicated that the corrosion depth for pure iron coated with Au disc films was about three times as that of bare pure iron. Both electrochemical test and immersion test revealed that the corrosion of pure iron matrix coated with Au disc array became more uniform.
Co-reporter:J. Cheng;T. Huang;Y. F. Zheng
Journal of Biomedical Materials Research Part A 2014 Volume 102( Issue 7) pp:2277-2287
Publication Date(Web):
DOI:10.1002/jbm.a.34882
Abstract
In this study, the effects of Fe2O3 (addition, 2, 5, 10, and 50 wt %) on the microstructure, mechanical properties, corrosion behaviors, and in vitro biocompatibility of Fe–Fe2O3 composites fabricated by spark plasma sintering were systematically investigated as a novel-structure biodegradable metallic material. The results of X-ray diffraction analysis and optical microscopy indicated that Fe–Fe2O3 composite is composed of α-Fe and FeO instead of Fe2O3. Both eletrochemical measurements and immersion test showed a faster degradation rate of Fe–2Fe2O3 and Fe–5Fe2O3 composites than pure iron and Fe–5Fe2O3 exhibited the fastest corrosion rate among these composites. Besides, the effect of Fe2O3 on the corrosion behavior of Fe–Fe2O3 composites was discussed. The extracts of Fe–Fe2O3 composite exhibited no cytotoxicity to both ECV304 and L929 cells, whereas greatly reduced cell viabilities of vascular smooth muscle cells. In addition, good hemocompatibility of all Fe–Fe2O3 composites and pure iron was obtained. To sum up, Fe–5Fe2O3 composite is a promising alternative for biodegradable stent material with elevated corrosion rate, enhanced mechanical properties, as well as excellent biocompatibility. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 102A: 2277–2287, 2014.
Co-reporter:Zhen Zhen, Tingfei Xi, Yufeng Zheng, Li Li, Lugee Li
Journal of Materials Science & Technology 2014 Volume 30(Issue 7) pp:675-685
Publication Date(Web):July 2014
DOI:10.1016/j.jmst.2014.04.005
The mechanical properties, chemical properties and biocompatibility of Mg–3Sn–0.5Mn alloy were tested. A series of in vitro evaluations such as tensile test, static and dynamic immersion test, hemocompatibility test as well as cytotoxicity test were presented, with commercial magnesium alloy WE43 as the control. Mg–3Sn–0.5Mn alloy possesses suitable strength and superior ductility compared with WE43 and AZ31. Static immersion and dynamic degradation tests showed more uniform degradation with a more moderate rate for Mg–3Sn–0.5Mn alloy (0.34 mm/y in static condition and 0.25 mm/y in dynamic condition) compared with WE43 alloy (0.42 mm/y in static condition and 0.33 mm/y in dynamic condition) in Hank's solution. Blood compatibility evaluation suggested that Mg–3Sn–0.5Mn alloy had no destructive effect on erythrocyte and showed excellent anti-thrombogenicity to blood system. Besides, Mg–3Sn–0.5Mn alloy showed no inhibition effect to L929 metabolic activity and mild toxicity to vascular smooth muscle cell (VSMC) in preliminary cell viability assessment. By considering its excellent mechanical strength, corrosion resistance, low ion release rate and good biocompatibility, Mg–3Sn–0.5Mn alloy may be a promising economical candidate as biomedical implant material for load-bearing clinical applications in the future.
Co-reporter:B. Tian, F. Chen, Y.X. Tong, L. Li, Y.F. Zheng, Q.Z. Li
Materials Letters 2014 Volume 116() pp:307-310
Publication Date(Web):1 February 2014
DOI:10.1016/j.matlet.2013.11.051
•Alloy changed from single phase to dual phase after adding Zr.•Formation of γ phase altered phase transformation temperature and enthalpy.•Transformation temperature and enthalpy of dual phase alloys changed after aging.This study investigated microstructure and phase transformation of Ni46Mn33Ga17Cu4−xZrx (x=0, 2, and 4) alloys. The substitution of Cu by Zr changed the alloy from a single martensite to a dual phase consisting of martensitic matrix and Zr-rich second γ phase at room temperature. The volume fraction of γ phase increased with the increase of Zr content, which resulted in the change of martensitic transformation temperature and transformation enthalpy of the alloys. After aging the dual phase alloys at 400 °C and 600 °C for 10 h, the martensitic transformation temperature was increased and transformation enthalpy was decreased.
Co-reporter:F.Y. Zhou, K.J. Qiu, D. Bian, Y.F. Zheng, J.P. Lin
Journal of Materials Science & Technology 2014 Volume 30(Issue 4) pp:299-306
Publication Date(Web):April 2014
DOI:10.1016/j.jmst.2013.12.006
Nb and Sn are major alloying elements in Zr alloys. In this study, the microstructure, mechanical properties, corrosion behavior, cytocompatibility and magnetic resonance imaging (MRI) compatibility of Zr–2.5X (X = Nb, Sn) alloys for biomedical application are comparatively investigated. It is found that Zr–2.5Nb alloy has a duplex structure of α and β phase and Zr–2.5Sn alloy is composed of α phase. Both separate addition of Nb and Sn can strengthen Zr but Nb is more effective in strengthening Zr than Sn. The studied Zr–2.5X (X = Nb, Sn) alloys show improved corrosion resistance compared to pure Zr as indicted by the decreased corrosion current density. The alloying addition of Nb enhances the pitting resistance of Zr, whereas the addition of Sn decreases the pitting resistance of Zr. The extracts of Zr–2.5X alloys produce no significant deleterious effect on fibroblast cells (L-929) and osteoblast-like cells (MG 63), indicating good in vitro cytocompatibility. The Zr–2.5X (X = Nb, Sn) alloys show decreased magnetic susceptibility compared to pure Zr and their magnetic susceptibility is far lower than that of pure Ti and Ti–6Al–4V alloy. Based on these facts, Zr–2.5Nb alloy is more suitable for implant material than Zr–2.5Sn alloy. Sn is not suitable as individual alloying addition for Zr because Sn addition decreases the pitting resistance in physiological solution.
Co-reporter:Y.F. Zheng, X.N. Gu, F. Witte
Materials Science and Engineering: R: Reports 2014 Volume 77() pp:1-34
Publication Date(Web):March 2014
DOI:10.1016/j.mser.2014.01.001
After decades of developing strategies to minimize the corrosion of metallic biomaterials, there is now an increasing interest to use corrodible metals in a number of medical device applications. The term “biodegradable metal” (BM) has been used worldwide to describe these new kinds of degradable metallic biomaterials for medical applications and there were many new findings reported over the last decade. In this paper, the definition of BM and its classification are given for the first time, along with the summary of the degradation mechanisms of BMs and its environmental influencing factors, which includes the degeneration of mechanical integrity and the metabolism of the degradation products. The recently-developed representative Mg-based BMs (pure Mg, Mg–Ca alloy, Mg–Zn alloy, etc.), Fe-based BMs (pure Fe, Fe–Mn-based alloys, etc.) and other BMs (pure W, pure Zn and its alloys, Ca-based and Sr-based bulk metallic glasses, etc.) were comprehensively reviewed with emphases on their microstructures, mechanical properties and degradation behaviors, in vitro and in vivo performances, pre-clinical and clinical trials. Moreover, current approaches to control their biodegradation rates to match the healing rates of the host tissues with various surface modification techniques and novel structural designs are summarized. Finally, this paper comprehensively discusses the directions of future development and the challenges of transitioning BMs from raw materials to semi-products to final medical devices. All in all, BM belongs to “bioactive” biomaterials and its future research and development direction should lean towards “third-generation biomedical materials” with “multifunctional capabilities” in a controllable manner to benefit the local tissue reconstruction.
Co-reporter:Huafang Li, Yufeng Zheng, Ling Qin
Progress in Natural Science: Materials International 2014 Volume 24(Issue 5) pp:414-422
Publication Date(Web):October 2014
DOI:10.1016/j.pnsc.2014.08.014
Biodegradable metals (BMs) are metals and alloys expected to corrode gradually in vivo, with an appropriate host response elicited by released corrosion products, then dissolve completely upon fulfilling the mission to assist with tissue healing with no implant residues. In the present review article, three classes of BMs have been systematically reviewed, including Mg-based, Fe-based and Zn-based BMs. Among the three BM systems, Mg-based BMs, which now have several systems reported the successful of clinical trial results, are considered the vanguards and main force. Fe-based BMs, with pure iron and Fe–Mn based alloys as the most promising, are still on the animal test stage. Zn-based BMs, supposed to have the degradation rate between the fast Mg-based BMs and the slow Fe-based BMs, are a rising star with only several reports and need much further research. The future research and development direction for the BMs are proposed, based on the clinical requirements on controllable degradation rate, prolonged mechanical stability and excellent biocompatibility, by optimization of alloy composition design, regulation on microstructure and mechanical properties, and following surface modification.
Co-reporter:F. L. Nie;Y. F. Zheng;Y. Wang;J. T. Wang
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2014 Volume 102( Issue 2) pp:221-230
Publication Date(Web):
DOI:10.1002/jbm.b.32998
Abstract
Bulk ultrafine-grained (UFG) pure Ta had been successfully prepared by equal channel angular pressing (ECAP) technique till eight passes. The 1st, 2nd, 4th, and 8th ECAPed Ta samples were investigated in the current study, with the 0th ECAPed Ta sample as the microcrystalline counterpart control. The microstructure and grain size distribution were characterized by X-ray diffractometer patterns, scanning electron microscopy, and transmission electron microscopy analysis by means of histogram. Although the mechanical behavior of all the experimental samples were analyzed through uniaxial tensile measurement and microhardness test, in vitro biological interactions onto the substrates such as protein adsorption, cellular responses derived from different types of cell lines, and the activity of erythrocyte and platelets were further evaluated and specifically assessed by bicinchoninic acid assay, enzyme-linked immunosorbent assay, and the method of colorimetric reading. A superior percentage of protein adsorption can be observed on the substrate of the UFG 8th ECAPed Ta (around 90%), even above those on the tissue culture plate (control) and the other ECAPed Ta samples. Furthermore, the UFG 8th ECAPed Ta shows no cytotoxic within 4 days culture when incubated with the murine fibroblast cell lines (L929). In addition, a priority order in the growth of endothelial cells (ECV304) other than vascular smooth muscle cells was observed in the case of the UFG 8th ECAPed Ta. In terms of hemolysis rate and adhered platelets (both the amount and the individual morphology), an evolutionary outcome of preferentially enhanced hemocompatibility can be concluded for the case of the UFG 8th ECAPed Ta. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 102B: 221–230, 2014.
Co-reporter:Huafang Li;Y. T. Pei
Journal of Materials Science: Materials in Medicine 2014 Volume 25( Issue 5) pp:1249-1255
Publication Date(Web):2014 May
DOI:10.1007/s10856-014-5158-8
This study explores the use of DC magnetron sputtering tungsten thin films for surface modification of TiNi shape memory alloy (SMA) targeting for biomedical applications. SEM, AFM and automatic contact angle meter instrument were used to determine the surface characteristics of the tungsten thin films. The hardness of the TiNi SMA with and without tungsten thin films was measured by nanoindentation tests. It is demonstrated that the tungsten thin films deposited at different magnetron sputtering conditions are characterized by a columnar microstructure and exhibit different surface morphology and roughness. The hardness of the TiNi SMA was improved significantly by tungsten thin films. The ion release, hemolysis rate, cell adhesion and cell proliferation have been investigated by inductively coupled plasma atomic emission spectrometry, CCK-8 assay and alkaline phosphatase activity test. The experimental findings indicate that TiNi SMA coated with tungsten thin film shows a substantial reduction in the release of nickel. Therefore, it has a better in vitro biocompatibility, in particular, reduced hemolysis rate, enhanced cell adhesion and differentiation due to the hydrophilic properties of the tungsten films.
Co-reporter:N. Li, Y.D. Li, Y.X. Li, Y.H. Wu, Y.F. Zheng, Y. Han
Materials Science and Engineering: C 2014 Volume 35() pp:314-321
Publication Date(Web):1 February 2014
DOI:10.1016/j.msec.2013.11.010
•Ultra-fine crystalline layers can be formed on pure Mg and Mg–1Ca alloy using SMAT.•The microhardness, surface roughness and wettability were enhanced after SMAT.•SMAT weakens the corrosion resistance of pure Mg and Mg–1Ca alloy.Surface mechanical attrition treatment (SMAT) is considered to be an effective approach to obtain a nanostructured layer in the treated surface of metals. In this study, we evaluated the effect of SMAT on the microstructure, mechanical properties and corrosion properties of biodegradable Mg–1Ca alloy, with pure Mg as control. Grain refinement layers with grain size at the nanometer scale in the topmost surface were successfully prepared on Mg–1Ca alloy using SMAT technique, similar to pure Mg. The SMAT not only refined the surface layer of Mg–1Ca alloy, but also promoted the re-dissolution of the Mg2Ca phase into the matrix. As a result, the microhardness of the SMATed samples in the near-surface region was considerably enhanced, and the surface roughness and wettability of the SMATed samples were increased. However, the SMAT led to high density of crystalline defects such as grain boundaries (subgrain boundaries) and dislocations, which severely weakened the corrosion resistance of Mg–1Ca alloy, same as pure Mg.
Co-reporter:K.J. Qiu, W.J. Lin, F.Y. Zhou, H.Q. Nan, B.L. Wang, L. Li, J.P. Lin, Y.F. Zheng, Y.H. Liu
Materials Science and Engineering: C 2014 Volume 34() pp:474-483
Publication Date(Web):1 January 2014
DOI:10.1016/j.msec.2013.10.004
•Mechanical properties of Ti–Ga alloys increased with the increase of Ga content.•Ti–2Ga showed an improved castability compared to pure Ti.•Ti–2Ga and Ti–5Ga alloys showed better corrosion resistance compared to pure Ti.•Ti–Ga alloys exhibited excellent in vitro biocompatibility as well as pure Ti.In this study, the microstructure, mechanical properties, castability, electrochemical behaviors and cytotoxicity of as-cast Ti–Ga alloys with pure Ti as control were systematically investigated to assess their potential application in dental field.The results of OM and XRD showed that the microstructure of all experimental as-cast Ti–Ga alloys exhibited single α-Ti phase at room temperature. Mechanical tests indicated that the tensile strength, Young's modulus, microhardness and wear resistance were improved monotonically with the increase of Ga content. The castability test showed that Ti–2Ga alloy increased the castability value of pure Ti by 14.2(± 3.8)% (p < 0.05). The electrochemical behaviors in both artificial saliva solutions indicated that the studied Ti–Ga alloys showed better corrosion resistance than pure Ti. The cytotoxicity test suggested that the studied Ti–Ga alloys produced no significant deleterious effect to L929 fibroblast cells and MG63 osteosarcoma cells, similar to pure Ti, indicating an excellent in vitro biocompatibility. The cell morphology test showed that both L929 and MG63 cells process excellent cell adhesion ability on all experimental materials. Considering all these results, Ti–2Ga alloy exhibits the optimal comprehensive performance and has potential for dental applications.
Co-reporter:T. Huang, J. Cheng, Y.F. Zheng
Materials Science and Engineering: C 2014 Volume 35() pp:43-53
Publication Date(Web):1 February 2014
DOI:10.1016/j.msec.2013.10.023
•The Fe–Pd and Fe–Pt composites prepared by spark plasma sintering have small grain size.•The addition of Pd or Pt greatly accelerated the degradation rate of pure iron.•Fe–Pd and Fe–Pt composites uniformly corroded in Hank's solution.•Fe–Pd and Fe–Pt composites both exhibited excellent in vitro biocompatibility.In order to obtain biodegradable Fe-based materials with similar mechanical properties as 316L stainless steel and faster degradation rate than pure iron, Fe-5 wt.%Pd and Fe-5 wt.%Pt composites were prepared by spark plasma sintering with powders of pure Fe and Pd/Pt, respectively. The grain size of Fe-5 wt.%Pd and Fe-5 wt.%Pt composites was much smaller than that of as-cast pure iron. The metallic elements Pd and Pt were uniformly distributed in the matrix and the mechanical properties of these materials were improved. Uniform corrosion of Fe–Pd and Fe–Pt composites was observed in both electrochemical tests and immersion tests, and the degradation rates of Fe–Pd and Fe–Pt composites were much faster than that of pure iron. It was found that viabilities of mouse fibroblast L-929 cells and human umbilical vein endothelial cells (ECV304) cultured in extraction mediums of Fe–Pd and Fe–Pt composites were close to that of pure iron. After 4 days' culture, the viabilities of L-929 and ECV304 cells in extraction medium of experimental materials were about 80%. The result of direct contact cytotoxicity also indicated that experimental materials exhibited no inhibition on vascular endothelial process. Meanwhile, iron ions released from experimental materials could inhibit proliferation of vascular smooth muscle cells (VSMC), which may be beneficial for hindering vascular restenosis. Furthermore, compared with that of as-cast pure iron, the hemolysis rates of Fe–Pd and Fe–Pt composites were slightly higher, but still within the range of 5%, which is the criteria for good blood compatibility. The numbers of platelet adhered on the surface of Fe–Pd and Fe–Pt composites were lower than that of pure iron, and the morphology of platelets kept spherical. To sum up, the Fe-5wt.%Pd and Fe-5wt.%Pt composites exhibited good mechanical properties and degradation behavior, closely approaching the requirements for biodegradable metallic stents.
Co-reporter:H.F. Li, X.H. Xie, K. Zhao, Y.B. Wang, Y.F. Zheng, W.H. Wang, L. Qin
Acta Biomaterialia 2013 Volume 9(Issue 10) pp:8561-8573
Publication Date(Web):November 2013
DOI:10.1016/j.actbio.2013.01.029
Abstract
In order to enhance the corrosion resistance of the Ca65Mg15Zn20 bulk metallic glass, which has too fast a degradation rate for biomedical applications, we fabricated the Ca20Mg20Zn20Sr20Yb20 high-entropy bulk metallic glass because of the unique properties of high-entropy alloys. Our results showed that the mechanical properties and corrosion behavior were enhanced. The in vitro tests showed that the Ca20Mg20Zn20Sr20Yb20 high-entropy bulk metallic glass could stimulate the proliferation and differentiation of cultured osteoblasts. The in vivo animal tests showed that the Ca20Mg20Zn20Sr20Yb20 high-entropy bulk metallic glass did not show any obvious degradation after 4 weeks of implantation, and they can promote osteogenesis and new bone formation after 2 weeks of implantation. The improved mechanical properties and corrosion behavior can be attributed to the different chemical composition as well as the formation of a unique high-entropy atomic structure with a maximum degree of disorder.
Co-reporter:W.R. Zhou, Y.F. Zheng, M.A. Leeflang, J. Zhou
Acta Biomaterialia 2013 Volume 9(Issue 10) pp:8488-8498
Publication Date(Web):November 2013
DOI:10.1016/j.actbio.2013.01.032
Abstract
Mg–Li-based alloys were investigated for future cardiovascular stent application as they possess excellent ductility. However, Mg–Li binary alloys exhibited reduced mechanical strengths due to the presence of lithium. To improve the mechanical strengths of Mg–Li binary alloys, aluminum and rare earth (RE) elements were added to form Mg–Li–Al ternary and Mg–Li–Al–RE quarternary alloys. In the present study, six Mg–Li–(Al)–(RE) alloys were fabricated. Their microstructures, mechanical properties and biocorrosion behavior were evaluated by using optical microscopy, X-ray diffraction, scanning electronic microscopy, tensile tests, immersion tests and electrochemical measurements. Microstructure characterization indicated that grain sizes were moderately refined by the addition of rare earth elements. Tensile testing showed that enhanced mechanical strengths were obtained, while electrochemical and immersion tests showed reduced corrosion resistance caused by intermetallic compounds distributed throughout the magnesium matrix in the rare-earth-containing Mg–Li alloys. Cytotoxicity assays, hemolysis tests as well as platelet adhesion tests were performed to evaluate in vitro biocompatibilities of the Mg–Li-based alloys. The results of cytotoxicity assays clearly showed that the Mg–3.5Li–2Al–2RE, Mg–3.5Li–4Al–2RE and Mg–8.5Li–2Al–2RE alloys suppressed vascular smooth muscle cell proliferation after 5 day incubation, while the Mg–3.5Li, Mg–8.5Li and Mg–8.5Li–1Al alloys were proven to be tolerated. In the case of human umbilical vein endothelial cells, the Mg–Li-based alloys showed no significantly reduced cell viabilities except for the Mg–8.5Li–2Al–2RE alloy, with no obvious differences in cell viability between different culture periods. With the exception of Mg–8.5Li–2Al–2RE, all of the other Mg–Li–(Al)–(RE) alloys exhibited acceptable hemolysis ratios, and no sign of thrombogenicity was found. These in vitro experimental results indicate the potential of Mg–Li–(Al)–(RE) alloys as biomaterials for future cardiovascular stent application and the worthiness of investigating their biodegradation behaviors in vivo.
Co-reporter:F.Y. Zhou, K.J. Qiu, H.F. Li, T. Huang, B.L. Wang, L. Li, Y.F. Zheng
Acta Biomaterialia 2013 Volume 9(Issue 12) pp:9578-9587
Publication Date(Web):December 2013
DOI:10.1016/j.actbio.2013.07.035
Abstract
In this study, the microstructures, mechanical properties, corrosion behaviors, in vitro cytocompatibility and magnetic susceptibility of Zr–1X alloys with various alloying elements, including Ti, Nb, Mo, Cu, Au, Pd, Ag, Ru, Hf and Bi, were systematically investigated to explore their potential use in biomedical applications. The experimental results indicated that annealed Zr–1X alloys consisted entirely or primarily of α phase. The alloying elements significantly increased the strength and hardness of pure Zr and had a relatively slight influence on elastic modulus. Ru was the most effective enhancing element and Zr–1Ru alloy had the largest elongation. The results of electrochemical corrosion indicated that adding various elements to Zr improved its corrosion resistance, as indicated by the reduced corrosion current density. The extracts of the studied Zr–1X alloys produced no significant deleterious effects on osteoblast-like cells (MG 63), indicating good in vitro cytocompatibility. All except for Zr–1Ag alloy showed decreased magnetic susceptibility compared to pure Zr, and Zr–1Ru alloy had the lowest magnetic susceptibility value, being comparable to that of α′ phase Zr–Mo alloy and Zr–Nb alloy and far lower than that of Co–Cr alloy and Ti–6Al–4V alloy. Among the experimental Zr–1X alloys, Zr–1Ru alloy possessing high strength coupled with good ductility, good in vitro cytocompatibility and low magnetic susceptibility may be a good candidate alloy for medical devices within a magnetic resonance imaging environment.
Co-reporter:F. L. Nie;Y. F. Zheng;S.C. Wei;D. S. Wang;Z. T. Yu;G. K. Salimgareeva;A. V. Polyakov;R. Z. Valiev
Journal of Biomedical Materials Research Part A 2013 Volume 101A( Issue 6) pp:1694-1707
Publication Date(Web):
DOI:10.1002/jbm.a.34472
Abstract
Bulk nanocrystalline Ti bars (Grade 4, ϕ4 × 3000 mm3) were massively fabricated by equal channel angular pressing (ECAP) via follow-up conform scheme with the microcrystalline CP Ti as raw material. Homogeneous nanostructured crystals with the average grain size of 250 nm were identified for the ECAPed Ti, with extremely high tensile/fatigue strength (around 1240/620 MPa) and adorable elongation (more than 5%). Pronounced formation of bonelike apatite for the nanocrystalline Ti group after 14 days static immersion in simulated body fluids (SBF) reveals the prospective in vitro bioactive capability of fast calcification, whereas an estimated 17% increment in protein adsorption represents good bioaffinity of nanocrystalline Ti. The documentation onto the whole life circle of osteoblast cell lines (MG63) revealed the strong interactions and superior cellular functionalization when they are co-incubated with bulk nanocrystalline Ti sample. Moreover, thread-structured specimens were designed and implanted into the tibia of Beagles dogs till 12 weeks to study the in vivo responses between bone and metallic implant made of bulk nanocrystalline Ti, with the microcrystalline Ti as control. For the implanted nanostructured Ti group, neoformed bone around the implants underwent the whole-stage transformation proceeding from originally osteons or immature woven bone to mature lamellar bone (skeletonic trabecular), even with the remodeling being finished till 12 weeks. The phenomenal osseointegration of direct implant-bone contact can be revealed from the group of the ECAPed Ti without fibrous tissue encapsulation in the gap between the implant and autogenous bone. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2013.
Co-reporter:Legan Hou, Li Li, Yufeng Zheng
Journal of Materials Science & Technology 2013 Volume 29(Issue 4) pp:330-338
Publication Date(Web):April 2013
DOI:10.1016/j.jmst.2013.02.013
Porous sintered Ti–Ag compacts with different Ag content were fabricated by powder metallurgy. The associated hydrothermal treatment and the effect on the apatite formation were studied. The results suggested that TiO was generated under the condition of low vacuum (1 × 10−2 Pa) during the process of burning out the spacer-holding particles. After hydrothermal treatment, a sub-microscale porous layer was formed at the pore wall surface of the samples. The apatite-inducing ability of hydrothermal treated porous sintered Ti–Ag compacts with different Ag content was evaluated in modified simulated body fluid (SBF). And the results proved that there is a clear correlation between the apatite-inducing ability and Ag content. The higher Ag content in porous leads to the decrease of Na+ ions and basic hydroxyl (OH)b amount, resulting in the decline of apatite-inducing ability in the first stage. However, their apatite-inducing ability was not significantly different from that of Ti after two weeks SBF immersing. Hence, the ionic activity should restore with the processing of SBF soaking, as the saturation of Ag effect.
Co-reporter:J. Cheng, B. Liu, Y.H. Wu, Y.F. Zheng
Journal of Materials Science & Technology 2013 Volume 29(Issue 7) pp:619-627
Publication Date(Web):July 2013
DOI:10.1016/j.jmst.2013.03.019
Five pure metals including Fe, Mn, Mg, Zn and W have been investigated on their corrosion behavior and in vitro biocompatibility by electrochemical measurement, static immersion test, contact angle measurement, cytotoxicity and hemocompatibility tests. It is found that the sequence of corrosion rate of five metals in Hank's solution from high to low is: Mg > Fe > Zn > Mn > W. Fe, Mg and W show no cytotoxicity to L929 and ECV304 cells, Mn induces significant cytotoxicity to both L929 and ECV304 cells, and Zn has almost no inhibition effect on the metabolic activities of ECV304 while largely reduces the cell viability of L929 cells. The hemolysis percentage of five pure metals is lower than 5% except for Mg and platelets adhered on Zn has been activated and pseudopodia-like structures can be observed while platelets on the other four metals keep normal.
Co-reporter:Y.H. Wu, N. Li, Y. Cheng, Y.F. Zheng, Y. Han
Journal of Materials Science & Technology 2013 Volume 29(Issue 6) pp:545-550
Publication Date(Web):June 2013
DOI:10.1016/j.jmst.2013.03.004
AZ31 magnesium alloy fibers reinforced poly(lactic-co-glycolic acid) (PLGA) composites were prepared and their mechanical property, immersion corrosion behavior and biocompatibility were studied. The tensile test showed that with the addition of AZ31 fibers, the composites had a significant increment in tensile strength and elongation. For the direct cell attachment test, all the cells showed a healthy morphology and spread well on the experimental sample surfaces. The immersion results indicated that pH values of the immersion medium increased with increasing AZ31 fiber contents. All the in vitro experimental results indicated that this new kind of magnesium alloy fibers reinforced PLGA composites show a potential for future biomedical applications.
Co-reporter:Nan Li, Yufeng Zheng
Journal of Materials Science & Technology 2013 Volume 29(Issue 6) pp:489-502
Publication Date(Web):June 2013
DOI:10.1016/j.jmst.2013.02.005
There is an increasing interest in the development of magnesium alloys both for industrial and biomedical applications. Industrial interest in magnesium alloys is based on strong demand of weight reduction of transportation vehicles for better fuel efficiency, so higher strength, and better ductility and corrosion resistance are required. Nevertheless, biomedical magnesium alloys require appropriate mechanical properties, suitable degradation rate in physiological environment, and what is most important, biosafety to human body. Rather than simply apply commercial magnesium alloys to biomedical field, new alloys should be designed from the point of view of nutriology and toxicology. This article provides a review of state-of-the-art of magnesium alloy implants and devices for orthopedic, cardiovascular and tissue engineering applications. Advances in new alloy design, novel structure design and surface modification are overviewed. The factors that influence the corrosion behavior of magnesium alloys are discussed and the strategy in the future development of biomedical magnesium alloys is proposed.
Co-reporter:Q.Y. Wang, Y.B. Wang, J.P. Lin, Y.F. Zheng
Materials Science and Engineering: C 2013 Volume 33(Issue 3) pp:1601-1606
Publication Date(Web):1 April 2013
DOI:10.1016/j.msec.2012.12.070
The objective of this study is to investigate the effect of alloying element indium on the microstructure, mechanical properties, corrosion behavior and in vitro cytotoxicity of Ti–In binary alloys, with the addition of 1, 5, 10 and 15 at.% indium. The phase constitution was studied by optical microscopic observation and X-ray diffraction measurements. The mechanical properties were characterized by tension and microhardness tests. Potentiodynamic polarization measurements were employed to investigate the corrosion behavior in artificial saliva solutions with and without fluoride. In vitro cytotoxicity was conducted by using L929 and NIH 3T3 mouse fibroblast cell lines, with commercially pure Ti (CP–Ti, ASTM grade 2) as negative control. All of the binary Ti–In alloys investigated in this work were found to have higher strength and microhardness than CP–Ti. Electrochemical results showed that Ti–In alloys exhibited the same order of magnitude of passivation current densities with CP–Ti in artificial saliva solutions. With the presence of NaF, Ti–10In and Ti–15In showed transpassive behavior and lower current densities at high potentials. All experimental Ti–In alloys showed good cytocompatibility, at the same level as CP–Ti. The addition of indium to titanium was effective on increasing the strength and microhardness, without impairing its good corrosion resistance and cytocompatibility.Highlights► The addition of In into Ti can increase the mechanical property. ► Ti-In alloys exhibited similar passivation behavior with CP-Ti. ► Ti-In alloys had good cytocompatibility comparable with CP-Ti. ► Ti-10In and Ti-15In showed transpassive baheviour with the addition of NaF.
Co-reporter:Z.X. Meng, H.F. Li, Z.Z. Sun, W. Zheng, Y.F. Zheng
Materials Science and Engineering: C 2013 Volume 33(Issue 2) pp:699-706
Publication Date(Web):1 March 2013
DOI:10.1016/j.msec.2012.10.021
Surface mineralization is an effective method to produce calcium phosphate apatite coating on the surface of bone tissue scaffold which could create an osteophilic environment similar to the natural extracellular matrix for bone cells. In this study, we prepared mineralized poly(d,l-lactide-co-glycolide) (PLGA) and PLGA/gelatin electrospun nanofibers via depositing calcium phosphate apatite coating on the surface of these nanofibers to fabricate bone tissue engineering scaffolds by concentrated simulated body fluid method, supersaturated calcification solution method and alternate soaking method. The apatite products were characterized by the scanning electron microscopy (SEM), Fourier transform-infrared spectroscopy (FT-IR), and X-ray diffractometry (XRD) methods. A large amount of calcium phosphate apatite composed of dicalcium phosphate dihydrate (DCPD), hydroxyapatite (HA) and octacalcium phosphate (OCP) was deposited on the surface of resulting nanofibers in short times via three mineralizing methods. A larger amount of calcium phosphate was deposited on the surface of PLGA/gelatin nanofibers rather than PLGA nanofibers because gelatin acted as nucleation center for the formation of calcium phosphate. The cell culture experiments revealed that the difference of morphology and components of calcium phosphate apatite did not show much influence on the cell adhesion, proliferation and activity.Highlights► Ca–P phases were coated on PLGA/gelatin electrospun nanofiber membranes within 3 h. ► Ca–P coatings prepared by 3 methods exhibited different structures and components. ► The Ca–P coating weight increase depends on the apatite nucleation velocity. ► Surface hydrophilicity enhanced the velocity and quantity of apatite nucleation. ► The resulting Ca–P apatite coatings exhibit good biocompatibility to MG63 cells.
Co-reporter:X.L. Liu, W.R. Zhou, Y.H. Wu, Y. Cheng, Y.F. Zheng
Materials Science and Engineering: C 2013 Volume 33(Issue 7) pp:4144-4154
Publication Date(Web):October 2013
DOI:10.1016/j.msec.2013.06.004
•The effect of sterilization on surface chemistry and biocompatibility was studied.•Sterilization caused more surface changes on MgCa alloy than pure Mg.•Co60 γ ray radiation is the most appropriate sterilization process.The aim of this work was to investigate the effect of various sterilization methods on surface characteristics and biocompatibility of MgCa alloy, with pure Mg as a comparison, including steam autoclave sterilization (SA), ethylene oxide steam sterilization (EO), glutaraldehyde sterilization (GD), dry heat sterilization (DH) and Co60 γ ray radiation sterilization (R) technologies. The surface characterizations were performed by environmental scanning electron microscopy, energy-dispersive X-ray spectroscopy, X-ray photoelectron spectroscopy, grazing incidence X-ray diffraction, water contact angle and surface free energy measurement, whereas the cytotoxicity and hemocompatibility were evaluated by cellular adhesive experiment, platelet adhesion and hemolysis test. The results showed that the five sterilization processes caused more changes on the surface of MgCa alloy than that on the surface of pure Mg. The GD sterilization caused the most obvious changes on the surface of the pure Mg, and the SA sterilization made the largest alteration on the MgCa alloy surface. The GD and DH sterilization processes could cause increases on surface free energy for both pure Mg and MgCa alloys, while the other three sterilization processes reduced the surface free energy. The DH and GD sterilization processes caused the least alteration on the cell adhesion on pure Mg surface, whereas the EO sterilization performed the greatest impact on the cell adhesion on the Mg–Ca alloy surface. The hemolysis percentage of pure Mg and MgCa alloys were reduced by SA sterilization, meanwhile the other four sterilization processes increased their hemolysis percentages significantly, especially for the EO sterilization.
Co-reporter:Y.B. Wang, H.F. Li, Y. Cheng, Y.F. Zheng, L.Q. Ruan
Materials Science and Engineering: C 2013 Volume 33(Issue 6) pp:3489-3497
Publication Date(Web):1 August 2013
DOI:10.1016/j.msec.2013.04.038
•Comparing with pure Ti, Ti-BMG shows superior mechanical properties with higher hardness and better wear resistance.•Ti-BMG shows great corrosion resistance close to pure Ti in electrochemical measurements.•Ti-BMG extracts had obvious low cell viability on both L929 and NIH3T3 cells.•The in vivo testing results proved that Ti-BMG could integrate with bone tissue, showing excellent osseointegration.In this study, a high glass forming system, Ti41.5Zr2.5Hf5Cu37.5Ni7.5Si1Sn5 (TZHCNSS) bulk metallic glass (BMG), is studied in terms of microstructure, surface analysis, mechanical properties, corrosion resistance, in vitro cytotoxicity and in vivo biocompatibility. It is found that the as-prepared TZHCNSS samples are fully amorphous by XRD and TEM observations, as well as DSC curve. Comparing with pure Ti, TZHCNSS BMG shows superior mechanical properties with higher hardness and better wear resistance. Due to the oxide film formed on its surface, TZHCNSS BMG shows great corrosion resistance close to pure Ti in electrochemical measurements. The pitting corrosion potential in artificial saliva solution is much higher than that in SBF solution. The indirect and direct cytotoxicity results show that TZHCNSS extracts had obvious low cell viability on both L929 and NIH3T3 cells. However, the in vivo testing results proved that TZHCNSS BMG could integrate with bone tissue, showing excellent osseointegration.
Co-reporter:X. X. Xu;M. H. Ding;J. X. Zhang;W. Zheng;L. Li;Y. F. Zheng
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2013 Volume 101( Issue 8) pp:1428-1436
Publication Date(Web):
DOI:10.1002/jbm.b.32962
Abstract
In this article, a novel composite of copper (Cu) nanoparticles and polydimethiylsiloxane (PDMS) has been prepared and investigated for the potential application in Cu-containing intrauterine device. The Cu/PDMS composite with various mass fraction of Cu nanoparticles was fabricated via the hot vulcanizing process. The chemical structures and surface morphologies of the Cu/PDMS composites were characterized confirming the physical interaction between Cu nanoparticles and PDMS. The surface morphology observation using scanning electron microscope and atomic force microscope showed the agglomeration of Cu nanoparticles in PDMS matrix and the distribution of the agglomerations was more uniform with increased amount of Cu nanoparticles. The cupric ion release behaviors of the Cu/PDMS composites with different amounts of Cu nanoparticles were investigated in simulated uterine fluid at 37°C for 150 days. The corrosion morphologies of the Cu/PDMS composites were also characterized. Both the burst release rate of the cupric ion in the first few days and the steady release rate after 30-day immersion were improved. The cytotoxicity test has been done for the Cu/PDMS composites. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 101B: 1428–1436, 2013.
Co-reporter:J. Cheng;Y.F. Zheng
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2013 Volume 101B( Issue 4) pp:485-497
Publication Date(Web):
DOI:10.1002/jbm.b.32783
Abstract
Early in vivo animal test on pure iron coronary stent had proved that it is a promising candidate material as biodegradable metal, despite a faster degradation rate and uniform degradation mode is expected. In this work, Fe-X (X= W, CNT) composites were prepared from powders of pure iron and the additive secondary phase X using the spark plasma sintering (SPS) method, aiming to obtain a higher corrosion rate and a more uniform corrosion mode in physiological environment. The microstructures, mechanical properties, corrosion behaviors, and in vitro biocompatibility of these Fe-X composites were investigated. It was found that the additives were uniformly distributed in the iron matrix and relatively high dense Fe-X composite bulk samples were obtained after sintering by SPS. Both the yield strength and ultimate compressive strength increased when compared with that of as-cast pure iron. The corrosion mode of Fe-X composites turned out to be uniform corrosion instead of localized corrosion. Electrochemical measurements and immersion tests indicated that the addition of W and CNT could increase the corrosion rate of the iron matrix. From the results of cytotoxicity evaluation, it was found that all the Fe-X composites extracts induced no obvious cytotoxicity to L929 cells and ECV304 cells whereas significantly decreased cell viabilities of VSMC cells. The hemocompatibility tests showed that all the hemolysis percentage of Fe-X composites were less than 5%, and no sign of thrombogenicity was observed. It might be concluded that Fe composited with suitable second phase can exhibit higher strength, faster degradation rate, and uniform degradation mode than those of pure iron and are promising candidates for future development of new degradable metallic stents. © 2013 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
Co-reporter:F. Y. Zhou;B. L. Wang;K. J. Qiu;L. Li;J. P. Lin;H. F. Li;Y. F. Zheng
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2013 Volume 101B( Issue 2) pp:237-246
Publication Date(Web):
DOI:10.1002/jbm.b.32833
Abstract
In this study, the microstructure, mechanical properties, corrosion behaviors, and in vitro biocompatibility of Zr–Mo alloys as a function of Mo content after solution treatment were systemically investigated to assess their potential use in biomedical application. The experimental results indicated that Zr–1Mo alloy mainly consisted of an acicular structure of α′ phase, while ω phase formed in Zr–3Mo alloy. In Zr–5Mo alloy, retained β phase and a small amount of precipitated α phase were observed. Only the retained β phase was obtained in Zr–10Mo alloy. Zr–1Mo alloy exhibited the greatest hardness, bending strength, and modulus among all experimental Zr–Mo alloys, while β phase Zr–10Mo alloy had a low modulus. The results of electrochemical corrosion indicated that adding Mo into Zr improved its corrosion resistance which resulted in increasing the thermodynamic stability and passivity of zirconium. The cytotoxicity test suggested that the extracts of the studied Zr–Mo alloys produced no significant deleterious effect to fibroblast cells (L-929) and osteoblast cells (MG 63), indicating an excellent in vitro biocompatibility. Based on these facts, certain Zr–Mo alloys potentially suitable for different biomedical applications were proposed. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2013.
Co-reporter:X.N. Gu, X.H. Xie, N. Li, Y.F. Zheng, L. Qin
Acta Biomaterialia 2012 Volume 8(Issue 6) pp:2360-2374
Publication Date(Web):July 2012
DOI:10.1016/j.actbio.2012.02.018
Abstract
Magnesium alloys have shown potential as biodegradable metallic materials for orthopedic applications due to their degradability, resemblance to cortical bone and biocompatible degradation/corrosion products. However, the fast corrosion rate and the potential toxicity of their alloying element limit the clinical application of Mg alloys. From the viewpoint of both metallurgy and biocompatibility, strontium (Sr) was selected to prepare hot rolled Mg–Sr binary alloys (with a Sr content ranging from 1 to 4 wt.%) in the present study. The optimal Sr content was screened with respect to the mechanical and corrosion properties of Mg–Sr binary alloys and the feasibility of the use of Mg–Sr alloys as orthopedic biodegradable metals was investigated by in vitro cell experiments and intramedullary implantation tests. The mechanical properties and corrosion rates of Mg–Sr alloys were dose dependent with respect to the added Sr content. The as-rolled Mg–2Sr alloy exhibited the highest strength and slowest corrosion rate, suggesting that the optimal Sr content was 2 wt.%. The as-rolled Mg–2Sr alloy showed Grade I cytotoxicity and induced higher alkaline phosphatase activity than the other alloys. During the 4 weeks implantation period we saw gradual degradation of the as-rolled Mg–2Sr alloy within a bone tunnel. Micro-computer tomography and histological analysis showed an enhanced mineral density and thicker cortical bone around the experimental implants. Higher levels of Sr were observed in newly formed peri-implant bone compared with the control. In summary, this study shows that the optimal content of added Sr is 2 wt.% for binary Mg–Sr alloys in the rolled state and that the as-rolled Mg–2Sr alloy in vivo produces an acceptable host response.
Co-reporter:X.X. Xu, F.L. Nie, Y.B. Wang, J.X. Zhang, W. Zheng, L. Li, Y.F. Zheng
Acta Biomaterialia 2012 Volume 8(Issue 2) pp:886-896
Publication Date(Web):February 2012
DOI:10.1016/j.actbio.2011.10.018
Abstract
To solve the main problems of existing coarse grained copper (CG Cu) intrauterine devices (IUD)—namely burst release and a low transfer efficiency of the cupric ions during usage—ultra-fine grained copper (UFG Cu) and single crystal copper (SC Cu) have been investigated as potential substitutes. Their corrosion properties with CG Cu as a control have been studied in simulated uterine fluid (SUF) under different conditions using electrochemical measurement methods. Long-term immersion of UFG Cu, SC Cu and CG Cu samples in SUF at 37 °C have been studied for 300 days. A lower copper ion burst release and a higher efficiency release of cupric ions were observed for UFG Cu and SC Cu compared with CG Cu in the first month of immersion and 2 months later. The respective corrosion mechanisms for UFG Cu, SC Cu and CG Cu in SUF are proposed. In vitro biocompatibility tests show a better cellular response to UFG Cu and SC Cu than CG Cu. In terms of instantaneous corrosion behavior, long-term corrosion performance and in vitro biocompatibility, the three pure copper materials follow the order: UFG Cu > SC Cu > CG Cu, which indicates that UFG Cu could be the most suitable candidate material for intrauterine devices.
Co-reporter:B.B. Zhang, K.J. Qiu, B.L. Wang, L. Li, Y.F. Zheng
Journal of Materials Science & Technology 2012 Volume 28(Issue 9) pp:779-784
Publication Date(Web):September 2012
DOI:10.1016/S1005-0302(12)60130-3
In this study, the surface passive films, dissolution behavior and biocompatibility of Ti-Ag alloys (with 5%, 10% and 20% Ag) were evaluated by X-ray diffraction (XRD) tests, electrochemical corrosion tests, X-ray photoelectron spectroscopy (XPS) tests, dissolution tests and in-vitro cytotoxicity tests. The surface films on the Ti-20Ag alloy are rich in Ti and much deficient in Ag with respect to alloy composition, as identified by XPS. Compared to CP Ti, Ti-5Ag and Ti-20Ag alloys show larger impedances and lower capacitances, which can be associated with an increase of the passive layer thickness. Moreover, all Ti-Ag alloys exhibit negligible or low metal release in the test solutions. The in-vitro cytotoxicity results show Ti-Ag alloys seem to be as cytocompatible as CP Ti. From the viewpoint of surface passive film and cytotoxicity, Ti-5Ag and Ti-20Ag are considered to be more suitable for dental applications.
Co-reporter:H.F. Li, Y.F. Zheng, F. Xu, J.Z. Jiang
Materials Letters 2012 Volume 75() pp:74-76
Publication Date(Web):15 May 2012
DOI:10.1016/j.matlet.2012.01.105
A series of novel Ni free Zr-based bulk metallic glasses (BMGs) with composition of Zr48Cu45Al7 (Ag0), Zr48Cu42Al7Ag3 (Ag3), Zr48Cu37Al7Ag8 (Ag8) Zr48Cu33Al8Ag11 (Ag11) were fabricated by arc-melting/copper mold suction-casting under a purified argon atmosphere. The microstructure, hardness, hemocompatibility and cellular responses were investigated in this study. The results indicated that the Ni free Zr-based BMGs exhibited much higher Vickers hardness than that of pure Zr. The Ni free Zr-based BMGs possessed a lower hemolysis ratio than the safe value of 5% according to ISO 10993–4 and a significant lower number density of adhered platelets. MTT assay results revealed that the relative growth rate (RGR) values of the Ni free Zr-based BMG samples were Grade 1 according to ISO 10993–5:2009, which means that the BMG samples have good cell viability.Highlights► A series of novel Ni free Zr-based bulk metallic glasses (BMGs) were fabricated. ► The Ni free Zr-based BMGs have much higher hardness than that of pure Zr. ► The Ni free Zr-based BMGs exhibit lower hemolysis ratio and platelets adhesion. ► The extracts of the Ni free Zr-based BMGs show good cell viability.
Co-reporter:Wen-Jiao Lin;Ben-Li Wang;Ke-Jin Qiu;Fei-Yu Zhou;Li Li;Jun-Pin Lin;Yan-Bo Wang;Yu-Feng Zheng
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2012 Volume 100B( Issue 8) pp:2239-2250
Publication Date(Web):
DOI:10.1002/jbm.b.32793
Abstract
As-cast Ti–xGe (x = 2, 5, 10, 20 wt %) binary alloys were produced in this work, and various experiments were carried out to investigate the microstructure, mechanical properties, in vitro electrochemical and immersion corrosion behaviors as well as cytotoxicity with as-cast pure Ti as control, aiming to study the feasibility of Ti–xGe alloy system as potential dental materials. The microstructure of Ti–xGe alloys changes from single α-Ti phase to α-Ti + Ti5Ge3 precipitation phase with the increase of Ge content. Mechanical tests show that Ti–5Ge alloy has the best comprehensive mechanical properties. The corrosion behavior of Ti–xGe alloys in artificial saliva with different NaF and lactic acid addition at 37°C indicates that Ti–2Ge and Ti–5Ge alloys show better corrosion resistance to fluorine-containing solution. The cytotoxicity test indicates that Ti–xGe alloy extracts show no obvious reduction of cell viability to L-929 fibroblasts and MG-63 osteosarcoma cells, similar to pure Ti which is generally acknowledged to be biocompatible. Considering all these results, Ti–2Ge and Ti–5Ge alloys possess the optimal comprehensive performance and might be used as potential dental materials. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Co-reporter:B.B. Zhang;B.L. Wang;Y.B. Wang;L. Li;Y.F. Zheng;Y. Liu
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2012 Volume 100B( Issue 1) pp:185-196
Publication Date(Web):
DOI:10.1002/jbm.b.31937
Abstract
A series of titanium-silver-iron ternary alloys have been prepared in this study, and their feasibility as dental materials has been evaluated by the microstructural examination, mechanical testing, corrosion resistance evaluation, surface analysis, and cytotoxicity tests. More and more β-Ti phase appears at room temperature and retains with the increasing of Fe content in Ti-5Ag-xFe alloy systems. The compression strength, wear resistance, and microhardness increase largely (p < 0.05) by the addition of element Fe to Ti-Ag alloy. Moreover, when comparing with commercial pure titanium (CP Ti), nobler electrochemical corrosion behavior could be obtained for Ti-5Ag-1Fe and Ti-5Ag-2.5Fe alloys in the 1% lactic acid solution (pH = 2.1) and 0.1 mol/L H2O2 + 0.9% NaCl solution (pH = 4.0). The released metal ions from Ti-5Ag-xFe alloys into the simulated fluid are trace, similar to the case of CP Ti. The addition of Fe slightly decreases the corrosion resistance of Ti-5Ag alloy. All experimental Ti-5Ag-xFe alloy extracts do not present any cytotoxicity to L-929 and NIH3T3 cell lines. All in all, the combination of superior corrosion resistance and enhanced mechanical properties make Ti-5Ag-1Fe alloy and Ti-5Ag-2.5Fe alloy suitable for dental applications. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Co-reporter:F. L. Nie;Y. F. Zheng
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2012 Volume 100B( Issue 5) pp:1404-1410
Publication Date(Web):
DOI:10.1002/jbm.b.32713
Abstract
Conventional microcrystalline pure iron (MC-Fe) becomes a new candidate as biodegradable metals, which has the insufficient physical feature and inferior biodegradation behavior. Novel bulk nanocrystalline pure iron (NC-Fe) was fabricated via equal channel angular pressing technique in the present work to overcome these problems. The contact angle test with water and glycerol droplets shows a smaller angle (though >90°) of NC-Fe than that of MC-Fe, which implies a lower surface energy of NC-Fe. The surface roughness of NC-Fe increased greatly than that of MC-Fe. A further comparative study of corrosion and electrochemistry performance between NC-Fe and its original MC-Fe was investigated in physiological saline with different dissolved oxygen concentration, aiming to in vitro simulate the corrosion process of coronary stent occurred in physiological environment. The electrochemical impedance spectra analysis and anodic polarization measurements indicated that the NC-Fe exhibited higher corrosion resistance than that of the MC-Fe; meanwhile obvious enhanced corrosion resistance with the decrement of dissolved oxygen concentration was observed. Related equivalent circuit model and surface reconstruction process were further discussed, and the degradation mechanism of the MC-Fe and NC-Fe were finally established. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Co-reporter:H. F. Li;Y. B. Wang;Y. F. Zheng;J. P. Lin
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2012 Volume 100B( Issue 7) pp:1721-1728
Publication Date(Web):
DOI:10.1002/jbm.b.32738
Abstract
The present study aimed to evaluate the osteoblast response on Ti- and Zr-based BMG surfaces sand blasted with different grit corundums for implant application, with mechanically polished disks before sand blasting as control groups. The surface properties were characterized by scanning electron microscopy (SEM), contact angle, and roughness measurements. Further evaluation of the surface bioactivity was conducted by MG63 cell attachment, proliferation, morphology, and alkaline phosphatase (ALP) activity on the sample surfaces. It was found that corundum sand blasting surfaces significantly increased the surface wettability and MG63 cell attachment, cell proliferation, and ALP activity in comparison with the control group surfaces. Besides, the sample surface treated by large grit corundum is more favorable for cell attachment, proliferation, and differentiation than samples treated by small grit corundum, indicating that it might be effective for improving implant osseointegration in vivo. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2012.
Co-reporter:Y.B. Wang, H.F. Li, Y.F. Zheng, M. Li
Materials Science and Engineering: C 2012 Volume 32(Issue 3) pp:599-606
Publication Date(Web):1 April 2012
DOI:10.1016/j.msec.2011.12.018
The aim of this work is to investigate the corrosion resistance and biocompatibility of three kinds of Fe based bulk metallic glasses (BMGs), Fe41Co7Cr15Mo14C15B6Y2 (BMG1), (Fe44Cr5Co5Mo13Mn11C16B6)98Y2 (BMG2), and Fe48Cr15Mo14C15B6Er2 (BMG3) by electrochemical measurements and indirect contact cytotoxicity assays, respectively. In comparison with 316 L SS biomedical steel, Fe based BMGs show better corrosion resistance in both simulated body fluids (Hank's solution and artificial saliva). The OCP curves show that the passive film on the Fe based BMG surfaces is quite stable, like 316 L SS. The corrosion current densities obtained from the anodic polarization curves from the lowest to highest are as follows: BMG3 < BMG1 < BMG2 < 316 L SS. The EIS analysis indicates that the Fe Based BMGs have larger polarization resistance value than that of 316 L SS except for BMG2 in artificial saliva. The pitting corrosion potentials of Fe based BMGs are much higher than that of the 316 L SS, resulting in very few ions releasing into the electrolytes while a significant amount of Ni and Fe ions release was found for 316 L SS under the same condition. The indirect cytotoxicity results suggest that all three Fe based BMG extracts have no cytotoxicity to L929 and NIH3T3 cells. All these results demonstrate that Fe based BMGs will open up a new path for the biomedical applications, especially in dental implantology.Highlights► Fe based BMGs show excellent corrosion resistance in simulated body fluids. ► Fe based BMGs have very few ions releasing into the electrolytes. ► Fe based BMG extracts have no cytotoxicity to L929 and NIH3T3 cells. ► Fe based BMGs will open up a new path in dental implantology.
Co-reporter:M. Guo, X. Wang, H.M. Zhou, L. Li, F.L. Nie, Y. Cheng, Y.F. Zheng
Materials Science and Engineering: C 2012 Volume 32(Issue 4) pp:909-915
Publication Date(Web):1 May 2012
DOI:10.1016/j.msec.2012.02.011
Porous silver scaffolds, with the porosity ranging from 68% to 81% and the apparent density ranging from 0.4 to 1 g⋅cm− 3 were prepared by electroplating method using cellular carbon skeleton as the substrate. The microstructure, mechanical property, cytotoxicity and antibacterial activity of the prepared porous silver scaffold were studied. The present porous silver scaffolds had a highly three-dimensional trabecular porous structure with the porosity and the apparent density close to that of the cancellous bone. Furthermore, the mechanical property such as elastic modulus and yield strength of the porous silver scaffolds were lower than that of commercial available porous Ti and porous Ti alloys but much closer to that of the cancellous bone and porous Ta. In addition, study of in vitro behavior showed that the porous silver scaffold possessed significant antibacterial capability of inhibition of bacterial proliferation and adherence against Staphylococcus aureus and Staphylococcus epidermidis, and little cytotoxicity to Mg-63 cell line and NIH-3T3 cell line. Consequently, the porous silver scaffolds prepared by electrodeposition possess a promising application for bone implants.Highlights► Porous Ag scaffolds were produced by electroplating Ag on cellular carbon skeleton. ► Porous Ag scaffolds have the porosity 68–81% and the apparent density 0.4–1 g⋅cm− 3. ► The mechanical property of porous Ag is close to cancellous bone and porous Ta. ► Porous Ag inhibits the proliferation and adherence of S. aureus and S. epidermidis.
Co-reporter:F.Y. Zhou, B.L. Wang, K.J. Qiu, W.J. Lin, L. Li, Y.B. Wang, F.L. Nie, Y.F. Zheng
Materials Science and Engineering: C 2012 Volume 32(Issue 4) pp:851-857
Publication Date(Web):1 May 2012
DOI:10.1016/j.msec.2012.02.002
In this work, the effects of Nb content on microstructure and corrosion behaviors of biomedical Zr–Nb alloys were systematically studied. The results of XRD analysis and optical microscopy indicated that the experimental Zr–Nb alloys had a duplex structure of α and β phases, and the content of β phase increased with the increase of Nb content. The electrochemical impedance spectroscopy (EIS) studies showed an improvement on the resistance of the spontaneous oxide film with increasing Nb content. The EIS data, fitted by Rs(QpRp) model, suggested a single passive film formed on the experimental material surfaces. Polarization tests in Hank's solution revealed a nobler electrochemical behavior of the Zr–Nb alloys after alloying Nb to pure Zr. The corrosion resistance increased with increasing Nb content, as indicated by lower corrosion current densities and passive current densities and higher pitting potentials. The major components on the surfaces of the corroded Zr–Nb alloy samples detected by XPS were ZrO2 and Nb2O5. The biocompatibility of Zr–Nb alloys was primarily evaluated by culturing L-929 cells in the extraction media of Zr–Nb alloy samples and excellent results were obtained. All of these above results suggested that the Zr–22Nb alloy, among the experimental alloys, showed a promising potential for biomedical applications.Highlights► Zr–Nb alloys had a duplex structure of α and β phases. ► Corrosion resistance was improved with the addition of Nb. ► Zr–Nb alloys became more pit-resistant with the increase of Nb content. ► All studied Zr–Nb alloys exhibited excellent in vitro biocompatibility.
Co-reporter:H. F. Li;K. Zhao;Y. B. Wang;Y. F. Zheng;W.H. Wang
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2012 Volume 100B( Issue 2) pp:368-377
Publication Date(Web):
DOI:10.1002/jbm.b.31958
Abstract
In this study, a novel Sr-based bulk metallic glass (BMG) with nominal composition of Sr40Mg20Zn15Yb20Cu5 (at.%) was fabricated with high-purity raw materials by induction-melting method. Its mechanical properties, corrosion behavior, and cellular compatibility were studied in vitro as a feasibility evaluation of potential biodegradable metal. The compression strength of Sr40Mg20Zn15Yb20Cu5 alloy was (408.2 ± 20.0) MPa, which was much higher than human bone (164–240 MPa). Its Young's modulus (20.6 ± 0.2) GPa was quite close to human bone (5–23 GPa). MTT assay and PNPP method were employed to measure the proliferation ability and ALP activity of the experimental Sr-based BMG. The results 0–1 grade cytotoxicity and high ALP activity revealed that it was harmless to osteoblast-like MG63 cells. Additionally, the cells cultured on the surface of Sr40Mg20Zn15Yb20Cu5 alloy plate exhibited polygonal and dorsal ruffle configuration, and were well attached to the substrate by cellular extension, indicating their healthy status. The combination of increased mechanical strength, greater corrosion resistance, and excellent biocompatibility makes the Sr40Mg20Zn15Yb20Cu5 BMG very attractive material for biodegradable orthopedic implant applications. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 100B: 368–377, 2012.
Co-reporter:Z.X. Meng, Q.T. Zeng, Z.Z. Sun, X.X. Xu, Y.S. Wang, W. Zheng, Y.F. Zheng
Colloids and Surfaces B: Biointerfaces 2012 Volume 94() pp:44-50
Publication Date(Web):1 June 2012
DOI:10.1016/j.colsurfb.2012.01.017
Surface entrapment is a convenient method to immobilize the natural macromolecules on the surface of synthetic polymers. In this study, the gelatin modified and sodium alginate/gelatin modified PLGA nanofibrous membranes were fabricated via surface entrapment and entrapment-graft techniques. The surface morphology of the each single modified PLGA nanofiber was as smooth as that of untreated PLGA nanofibers. The results of water angle contact measurements and tensile tests showed that the surface entrapment cannot only improve the hydrophilicity but also enhance mechanical properties of the modified nanofibrous membranes. In addition, the sodium alginate/gelatin modified electrospun PLGA nanofibrous membrane exhibited higher hydrophilicity and better biocompatibility than the simply gelatin modified PLGA nanofibrous membrane, which suggested the surface entrapment is a facile and efficient approach to surface modification for electrospun nanofibours membranes.Graphical abstractHighlights► The gelatin modified PLGA and sodium alginate/gelatin modified PLGA nanofibrous membranes were fabricated through surface entrapment and entrapment-graft treatment. ► Both gelatin modified PLGA and sodium alginate/gelatin modified PLGA nanofibrous membranes have not only enhanced the hydrophilicity but also improved mechanical properties. ► The sodium alginate/gelatin modified electrospun PLGA nanofibrous membrane exhibited better hydrophilicity and biocompatibility than the simple gelatin modified PLGA nanofibrous membrane.
Co-reporter:X.N. Gu, W.R. Zhou, Y.F. Zheng, Y. Cheng, S.C. Wei, S.P. Zhong, T.F. Xi, L.J. Chen
Acta Biomaterialia 2011 Volume 7(Issue 4) pp:1938
Publication Date(Web):April 2011
DOI:10.1016/j.actbio.2010.12.011
Co-reporter:Y.F. Zheng, B.B. Zhang, B.L. Wang, Y.B. Wang, L. Li, Q.B. Yang, L.S. Cui
Acta Biomaterialia 2011 Volume 7(Issue 6) pp:2758-2767
Publication Date(Web):June 2011
DOI:10.1016/j.actbio.2011.02.010
Abstract
A new kind of biomedical shape memory TiNiAg alloy with antibacterial function was successfully developed in the present study by the introduction of pure Ag precipitates into the TiNi matrix phase. The microstructure, mechanical property, corrosion resistance, ion release behavior in simulated body fluid, cytotoxicity and antibacterial properties were systematically investigated. The typical microstructural feature of TiNiAg alloy at room temperature was tiny pure Ag particles (at submicrometer or micrometer scales with irregular shape) randomly distributed in the TiNi matrix phase. The presence of Ag precipitates was found to result in a slightly higher tensile strength and larger elongation of TiNiAg alloy in comparison with that of TiNi binary alloy. Furthermore, a maximum shape recovery strain of ∼6.4% was obtained with a total prestrain of 7% in the TiNiAg alloy. In electrochemical and immersion tests, TiNiAg alloy presented good corrosion resistance in simulated body fluid, comparable with that of CP Ti and TiNi alloy. The cytotoxicity evaluation revealed that TiNiAg alloy extract induced slight toxicity to cells, but the viability of experimental cells was similar to or higher than that of TiNi alloy extract. In vitro bacterial adhesion study indicated a significantly reduced number of bacteria (S. aureus, S. epidermidis and P. gingivalis) on the TiNiAg alloy plate surface when compared with that on TiNi alloy plate surface, and the corresponding antibacterial mechanism for the TiNiAg alloy is discussed.
Co-reporter:B. Liu, Y.F. Zheng
Acta Biomaterialia 2011 Volume 7(Issue 3) pp:1407-1420
Publication Date(Web):March 2011
DOI:10.1016/j.actbio.2010.11.001
Abstract
Pure iron was determined to be a valid candidate material for biodegradable metallic stents in recent animal tests; however, a much faster degradation rate in physiological environments was desired. C, Mn, Si, P, S, B, Cr, Ni, Pb, Mo, Al, Ti, Cu, Co, V and W are common alloying elements in industrial steels, with Cr, Ni, Mo, Cu, Ti, V and Si being acknowledged as beneficial in enhancing the corrosion resistance of iron. The purpose of the present work (using Fe–X binary alloy models) is to explore the effect of the remaining alloying elements (Mn, Co, Al, W, B, C and S) and one detrimental impurity element Sn on the biodegradability and biocompatibility of pure iron by scanning electron microscopy, X-ray diffraction, metallographic observation, tensile testing, microhardness testing, electrochemical testing, static (for 6 months) and dynamic (for 1 month with various dissolved oxygen concentrations) immersion testing, cytotoxicity testing, hemolysis and platelet adhesion testing. The results showed that the addition of all alloying elements except for Sn improved the mechanical properties of iron after rolling. Localized corrosion of Fe–X binary alloys was observed in both static and dynamic immersion tests. Except for the Fe–Mn alloy, which showed a significant decrease in corrosion rate, the other Fe–X binary alloy corrosion rates were close to that of pure iron. It was found that compared with pure iron all Fe–X binary alloys decreased the viability of the L929 cell line, none of experimental alloying elements significantly reduced the viability of vascular smooth muscle cells and all the elements except for Mn increased the viability of the ECV304 cell line. The hemolysis percentage of all Fe-X binary alloy models were less than 5%, and no sign of thrombogenicity was observed. In vitro corrosion and the biological behavior of these Fe–X binary alloys are discussed and a corresponding mechanism of corrosion of Fe–X binary alloys in Hank’s solution proposed. As a concluding remark, Co, W, C and S are recommended as alloying elements for biodegradable iron-based biomaterials.
Co-reporter:Y.B. Wang, X.H. Xie, H.F. Li, X.L. Wang, M.Z. Zhao, E.W. Zhang, Y.J. Bai, Y.F. Zheng, L. Qin
Acta Biomaterialia 2011 Volume 7(Issue 8) pp:3196-3208
Publication Date(Web):August 2011
DOI:10.1016/j.actbio.2011.04.027
Abstract
A low density and high strength alloy, Ca65Mg15Zn20 bulk metallic glass (CaMgZn BMG), was evaluated by both in vitro tests on ion release and cytotoxicity and in vivo implantation, aimed at exploring the feasibility of this new biodegradable metallic material for potential skeletal applications. MTT assay results showed that the experimental CaMgZn BMG extracts had no detectable cytotoxic effects on L929, VSMC and ECV304 cells over a wide range of concentrations (0–50%), whereas for MG63 cells concentrations in the range ∼5–20% promoted cell viability. Meanwhile, alkaline phosphatase (ALP) activity results showed that CaMgZn BMG extracts increased alkaline phosphatase (ALP) production by MG63 cells. However, Annexin V–fluorescein isothiocyanate and propidium iodide staining indicated that higher concentrations (50%) might induce cell apoptosis. The fluorescence observation of F-actin and nuclei in MG63 cells showed that cells incubated with lower concentrations (0–50%) displayed no significant change in morphology compared with a negative control. Tumor necrosis factor-α expression by Raw264.7 cells in the presence of CaMgZn BMG extract was significantly lower than that of the positive and negative controls. Animal tests proved that there was no obvious inflammation reaction at the implantation site and CaMgZn BMG implants did not result in animal death. The cortical thickness around the CaMgZn BMG implant increased gradually from 1 to 4 weeks, as measured by in vivo micro-computer tomography.
Co-reporter:X.N. Gu, N. Li, W.R. Zhou, Y.F. Zheng, X. Zhao, Q.Z. Cai, Liquan Ruan
Acta Biomaterialia 2011 Volume 7(Issue 4) pp:1880-1889
Publication Date(Web):April 2011
DOI:10.1016/j.actbio.2010.11.034
Abstract
The Mg–Ca alloy system has been proposed as a potential new kind of degradable biomaterial with possible application within bone. Here microarc oxidation (MAO) coatings were fabricated on top of a Mg–Ca alloy using different applied voltages and the effect of applied voltage on the surface morphology and phase constitution, hydrogen evolution, pH variation in the immersion solution and in vitro biocompatibility of the MAO coating on the Mg–Ca alloy were extensively studied. It was found that the thickness and pore size of the MAO coating increased with the increasing applied voltage, whereas some micro-pores could be seen inside the 400 V treated MAO coating. The 360 V treated MAO coating gave the best long-term corrosion resistance during a 50 days immersion test. All the MAO coatings could promote MG63 cell adhesion, proliferation and differentiation in comparison with the uncoated Mg–Ca alloy sample, due to significantly reduced Mg ion release and pH value variations in the culture medium. After 5 days culture well-spread and elongated MG63 cells could be seen on the surface of the 360 V and 400 V MAO coatings, in contrast to no cells on the uncoated Mg–Ca alloy sample. In summary, MAO showed beneficial effects on the corrosion resistance of, and thus improved cell adhesion to, the Mg–Ca alloy, and should be a good surface modification method for other biomedical magnesium alloys.
Co-reporter:B. Tian, F. Chen, Y.X. Tong, L. Li, Y.F. Zheng, Y. Liu, Q.Z. Li
Journal of Alloys and Compounds 2011 Volume 509(Issue 13) pp:4563-4568
Publication Date(Web):31 March 2011
DOI:10.1016/j.jallcom.2011.01.104
This study investigated the phase transformation of the flaky shaped Ni–Mn–Ga powder particles with thickness around 1 μm prepared by vibration ball milling and post-annealing. The SEM, XRD, DSC and ac magnetic susceptibility measurement techniques were used to characterize the Ni–Mn–Ga powders. The structural transition of Heusler → disordered fcc occurred in the powders prepared by vibration ball milling (high milling energy) for 4 h, which was different from the structural transition of Heusler → disordered fct of the powders fabricated by planetary ball milling (low milling energy) for 4 h. The two different structures after ball milling should be due to the larger lattice distortion occurred in the vibration ball milling process than in the planetary ball milling process. The structural transition of disordered fcc → disordered bcc took place at ∼320 °C during heating the as-milled Ni–Mn–Ga powders, which was attributed to the elimination of lattice distortion caused by ball milling. The activation energy for this transition was 209 ± 8 kJ/mol. The Ni–Mn–Ga powder annealed at 800 °C mainly contained Heusler austenite phase at room temperature and showed a low volume of martensitic transformation upon cooling. The inhibition of martensitic transformation might be attributed to the reduction of grain size in the annealed Ni–Mn–Ga particles.Research highlights► The vibration ball milling with a high milling energy introduces the atomic disorder and large lattice distortion in the alloy during milling and makes the formation of disordered fcc structure phase in the alloy. ► The transition temperature and activation energy for disordered fcc → disordered bcc are ∼320 °C and 209 ± 8 kJ/mol, respectively. ► The alloy powders annealed at 800 °C for 1 h show a one-stage martensitic transformation with quite lower latent heat compared to the bulk alloy.
Co-reporter:C.Y. Zheng, F.L. Nie, Y.F. Zheng, Y. Cheng, S.C. Wei, R.Z. Valiev
Applied Surface Science 2011 Volume 257(Issue 21) pp:9086-9093
Publication Date(Web):15 August 2011
DOI:10.1016/j.apsusc.2011.05.105
Abstract
Bulk ultrafine-grained Ni50.8Ti49.2 alloy (UFG-NiTi) was successfully fabricated by equal-channel angular pressing (ECAP) technique in the present study, and to further improve its surface biocompatibility, surface modification techniques including sandblasting, acid etching and alkali treatment were employed to produce either irregularly roughened surface or microporous surface or hierarchical porous surface with bioactivity. The effect of the above surface treatments on the surface roughness, wettability, corrosion behavior, ion release, apatite forming ability and cytocompatibility of UFG-NiTi alloy were systematically investigated with the coarse-grained NiTi alloy as control. The pitting corrosion potential (Epit) was increased from 393 mV (SCE) to 704 mV (SCE) with sandblasting and further increased to 1539 mV (SCE) with following acid etching in HF/HNO3 solution. All the above surface treatment increased the apatite forming ability of UFG-NiTi in varying degrees when soaked them in simulated body fluid (SBF). Meanwhile, both sandblasting and acid etching could promote the cytocompatibility for osteoblasts: sandblasting enhanced cell attachment and acid etching increased cell proliferation. The different corrosion behavior, apatite forming ability and cellular response of UFG-NiTi after different surface modifications are attributed to the topography and wettability of the resulting surface oxide layer.
Co-reporter:C.Y. Zheng, F.L. Nie, Y.F. Zheng, Y. Cheng, S.C. Wei, Liqun Ruan, R.Z. Valiev
Applied Surface Science 2011 Volume 257(Issue 13) pp:5913-5918
Publication Date(Web):15 April 2011
DOI:10.1016/j.apsusc.2011.02.006
Abstract
NiTi alloy has a unique combination of mechanical properties, shape memory effects and superelastic behavior that makes it attractive for several biomedical applications. In recent years, concerns about its biocompatibility have been aroused due to the toxic or side effect of released nickel ions, which restricts its application as an implant material. Bulk ultrafine-grained Ni50.8Ti49.2 alloy (UFG NiTi) was successfully fabricated by equal-channel angular pressing (ECAP) technique in the present study. A homogeneous and smooth SrO–SiO2–TiO2 sol–gel coating without cracks was fabricated on its surface by dip-coating method with the aim of increasing its corrosion resistance and cytocompatibility. Electrochemical tests in simulated body fluid (SBF) showed that the pitting corrosion potential of UFG NiTi was increased from 393 mV(SCE) to 1800 mV(SCE) after coated with SrO–SiO2–TiO2 film and the corrosion current density decreased from 3.41 μA/cm2 to 0.629 μA/cm2. Meanwhile, the sol–gel coating significantly decreased the release of nickel ions of UFG NiTi when soaked in SBF. UFG NiTi with SrO–SiO2–TiO2 sol–gel coating exhibited enhanced osteoblast-like cells attachment, spreading and proliferation compared with UFG NiTi without coating and CG NiTi.
Co-reporter:C.Y. Zheng, F.L. Nie, Y.F. Zheng, Y. Cheng, S.C. Wei, R.Z. Valiev
Applied Surface Science 2011 Volume 257(Issue 13) pp:5634-5640
Publication Date(Web):15 April 2011
DOI:10.1016/j.apsusc.2011.01.062
Abstract
Bulk ultrafine-grained Ti (UFG Ti) was successfully fabricated by equal-channel angular pressing (ECAP) technique in the present study, and to further improve its surface biocompatibility, surface modification techniques including sandblasting, acid etching and alkali treatment were employed to produce a hierarchical porous surface. The effect of the above surface treatments on the surface roughness, wettability, electrochemical corrosion behavior, apatite forming ability and cellular behavior of UFG Ti were systematically investigated with the coarse-grained Ti as control. Results show that UFG-Ti with surface modification had no pitting corrosion and presented low corrosion rate in simulated body fluids (SBF). The hierarchical porous surface yielded by surface modification enhanced the ability of UFG Ti to form a complete apatite layer when soaked in SBF and promoted osteoblast-like cells attachment and proliferation in vitro, which promises to have a significant impact on increasing bone-bonding ability and reducing healing time when implanted due to faster tissue integration.
Co-reporter:W. Jiao, H.F. Li, K. Zhao, H.Y. Bai, Y.B. Wang, Y.F. Zheng, W.H. Wang
Journal of Non-Crystalline Solids 2011 Volume 357(22–23) pp:3830-3840
Publication Date(Web):15 November 2011
DOI:10.1016/j.jnoncrysol.2011.08.003
We report the development of a CaZn based bulk glassy alloy (BGA) with combining properties of low Young's modulus, high fracture strength, good corrosion resistance and cytocompatibility, which make it be potential as biodegradable bone graft substitute. Compared to commonly investigated biodegradable metals, the Young's modulus of the BGA is closer to that of cortical bone, and its fracture strength reaches 600 MPa, which is 2 times higher than that of pure magnesium. The magnetic susceptibility of the CaZn based BGA is as low as 22.3 × 10− 6, which is compatible with magnetic resonance imaging (MRI) diagnosis. The BGAs also show slow degradation rate and good cytocompatibility. The new class of biodegradable CaZn based BGAs enriches the family of biomaterials, and the work has implications for developing new biodegradable alloys with active elements. The formation and the origins of excellent properties of the BGA are discussed.Highlights► The development of a CaZn based bulk glassy alloy has potential as biodegradable bone graft substitute. ► The materials also show slow degradation rate and good cytocompatibility. ► A new class of biodegradable CaZn based metallic glasses.
Co-reporter:Z.X. Meng, W. Zheng, L. Li, Y.F. Zheng
Materials Chemistry and Physics 2011 Volume 125(Issue 3) pp:606-611
Publication Date(Web):15 February 2011
DOI:10.1016/j.matchemphys.2010.10.010
In this study both aligned and randomly oriented poly(d,l-lactide-co-glycolide) (PLGA)/chitosan nanofibrous scaffold have been prepared by electrospinning. The ratio of PLGA to chitosan was adjusted to get smooth nanofiber surface. Morphological characterization using scanning electron microscopy showed that the aligned nanofiber diameter distribution obtained by electrospinning of polymer blend increased with the increase of chitosan content which was similar to that of randomly oriented nanofibers. The release characteristic of model drug fenbufen (FBF) from the FBF-loaded aligned and randomly oriented PLGA and PLGA/chitosan nanofibrous scaffolds was investigated. The drug release rate increased with the increase of chitosan content because the addition of chitosan enhanced the hydrophilicity of the PLGA/chitosan composite scaffold. Moreover, for the aligned PLGA/chitosan nanofibrous scaffold the release rate was lower than that of randomly oriented PLGA/chitosan nanofibrous scaffold, which indicated that the nanofiber arrangement would influence the release behavior. In addition, crosslinking in glutaraldehyde vapor would decrease the burst release of FBF from FBF-loaded PLGA/chitosan nanofibrous scaffold with a PLGA/chitosan ratio less than 9/1, which would be beneficial for drug release.Graphical abstractThe fenbufen loaded PLGA/chitosan nanofibrous scaffolds were fabricated by electrospinning. The hydrophilicity of nanofibrous scaffold was enhanced with the increase of chitosan content. The drug release also is accelerated with chitosan increasing because the higher hydrophilicity makes drug diffusing from scaffold more easily.Research highlights▶ The average diameter increased with the increase of chitosan content and then decreased. ▶ The release rate of fenbufen increased with the increase of chitosan. ▶ The aligned nanofibrous scaffold exhibits lower drug release rate. ▶ The drug release could be controlled by crosslinking in glutaraldehyde vapor.
Co-reporter:Huafang Li;Junpin Lin
Advanced Engineering Materials 2011 Volume 13( Issue 5) pp:B187-B193
Publication Date(Web):
DOI:10.1002/adem.201080110
Abstract
The corrosion resistance of Ti45Al8.5Nb intermetallic alloy in artificial saliva and its cytocompatibility was studied via electrochemical tests, scanning electron microscopy, ion release measurement, and MTT assay, with contemporary biomedical Ti6Al4V and Ti6Al7Nb alloys as comparison. The results demonstrate that the corrosion potential (Ecorr) and the corrosion current density (icorr) of the three experimental alloy samples are similar and there is no statistically significant difference among them (p > 0.05). The Al3+ ion releasing concentration for Ti45Al8.5Nb intermetallic and Ti6Al7Nb alloy after anodic polarization are close. The relative cell proliferation rates of the three experimental alloy extract groups are all over 90% at various cultivation periods (1, 3, and 5 d), and there is no obvious difference for the MG63 cell morphologies comparing with that of the negative group, reaching confluence after 5 d culture and showing well stretched, which indicates that Ti45Al8.5Nb intermetallic alloy has a good cytocompatibility with the Grade 1 RGR value (no toxicity) according to ISO 10993-5: 1999.
Co-reporter:Q.Y. Wang, Y.F. Zheng, Y. Liu
Materials Letters 2011 Volume 65(Issue 1) pp:74-77
Publication Date(Web):15 January 2011
DOI:10.1016/j.matlet.2010.09.036
The aim of this study is to investigate the microstructure, martensitic transformation behavior, shape memory effect and superelastic property of Ti49.6Ni45.1Cu5Cr0.3 alloy, with Cu and Cr substituting for Ni. After annealing, the alloy showed single step A–M/M–A transformations within the whole annealing temperature range of 623 K to 1273 K even in the presence and Ti2(Ni, Cu) precipitates. With the increase of the annealing temperature, the transformation temperatures exhibited three stages: increasing from 623 K to 873 K, decreasing from 873 K to 1023 K and unchanging from 1023 K to 1273 K. Meanwhile, the critical stress for stress induced martensitic (SIM) transformation decreased to a minimum value and increased after that, exhibiting a V shape curve. The alloy annealed at 623, 773 and 923 K exhibited shape recovery ratio more than 90% when the deformation strain was below 20%.
Co-reporter:B. Liu, Y.F. Zheng, Liquan Ruan
Materials Letters 2011 Volume 65(Issue 3) pp:540-543
Publication Date(Web):15 February 2011
DOI:10.1016/j.matlet.2010.10.068
Fe30Mn6Si alloy was investigated as a potential degradable biomaterial, with the recently well-developed biodegradable metals, pure iron and Fe30Mn alloy, as comparison. The microstructure, mechanical properties, shape memory effect, corrosion behavior and in vitro biocompatibilities were evaluated by X-ray diffraction, scanning electron microscopy, tensile tests, electrochemical tests, immersion tests in Hank's solution till 6 months, cytotoxicity and hemolysis tests. It's found that Fe30Mn6Si alloy consists of ε-martensite and γ-austenite at room temperature, the mechanical property of Fe30Mn6Si alloy is higher than that of the pure iron, and the corrosion rate of Fe30Mn6Si alloy is higher than that of Fe30Mn alloy. Additionally, Fe30Mn6Si alloy shows good performance for blood vessel related cellular application and the hemolysis percentage is less than 2%. In conclusion, Fe30Mn6Si alloy is a promising biodegradable metallic material with a shape memory function.
Co-reporter:Z.X. Meng, X.X. Xu, W. Zheng, H.M. Zhou, L. Li, Y.F. Zheng, X. Lou
Colloids and Surfaces B: Biointerfaces 2011 Volume 84(Issue 1) pp:97-102
Publication Date(Web):1 May 2011
DOI:10.1016/j.colsurfb.2010.12.022
Drug (Fenbufen, FBF)-loaded poly(d,l-lactide-co-glycolide) (PLGA) and PLGA/gelatin nanofibrous scaffolds were fabricated via electrospinning technique. The influences of gelatin content, fiber arrangement, crosslinking time and pH value of the buffer solution on FBF release behavior of the resulting nanofibrous scaffolds were investigated, with the corresponding FBF-loaded PLGA and PLGA/gelatin solvent-cast films as controls. The release rate of FBF was found to be increased with the increment of gelatin content for all the composite samples, and the FBF release rate of aligned nanofibrous scaffold was lower than that of randomly oriented scaffold. Moreover, the crosslinking treatment depressed effectively the burst release of FBF at initial release stage of PLGA/gelatin (9/1) nanofibrous scaffold. In addition, the pH value of the buffer solution could change the physical state of the polymer and affect the FBF release rate.Graphical abstractDrug-loaded electrospun nanofibers and films were fabricated in this study. The drug release of nanofibers was higher than that of films. The nanofibers possessed larger surface than films that drug could diffuse from the matrix easier. Additionally, amorphous state of drug in nanofibers and crystal in films made the different release behavior between nanofibers and films.Research highlights▶ The release rate of FBF was found to increase with the increment of gelatin content. ▶ The FBF release rate of aligned nanofibrous scaffold was lower than that of randomly oriented scaffold. ▶ The crosslinking treatment decreased the burst release of FBF at initial release stage. ▶ The pH value of the buffer solution could affect the FBF release rate.
Co-reporter:X.X. Xu, J.X. Zhang, F. Guo, W. Zheng, H.M. Zhou, B.L. Wang, Y.F. Zheng, Y.B. Wang, Y. Cheng, X. Lou, B.Z. Jang
Colloids and Surfaces B: Biointerfaces 2011 Volume 84(Issue 2) pp:427-432
Publication Date(Web):1 June 2011
DOI:10.1016/j.colsurfb.2011.01.037
In this paper, an amperometric biosensor of hydrogen peroxide (H2O2) was fabricated by immobilization of Hemoglobin (Hb) on a Pluronic P123-nanographene platelet (NGP) composite. Direct electron transfer in the Hb-immobilized P123-NGP composite film was greatly facilitated. The surface concentration (Γ*) and apparent heterogeneous electron transfer rate constant (ks) were calculated to be (1.60 ± 0.17) × 10−10 mol cm−2 and 48.51 s−1, respectively. In addition, the Hb/Pluronic P123-NGP composite showed excellent bioelectrocatalytic activity toward the reduction of H2O2. The biosensor of H2O2 exhibited a linear response to H2O2 in the range of 10–150 μM and a detection limit of 8.24 μM (S/N = 3) was obtained. The apparent Michaelis–Menten constant (Kmapp) was 45.35 μM. The resulting biosensor showed fast amperometric response, with very high sensitivity, reliability and effectiveness.Graphical abstractResearch highlights► An amperometric biosensor of hydrogen peroxide (H2O2) was substantially facilitated by immobilized Hemoglobin (Hb) in Pluronic P123-nanographene platelets (NGPs) composite. ► The surface concentration (Γ*) and the apparent heterogeneous electron transfer rate constant (ks) were calculated as (1.60 ± 0.17) × 10−10 mol cm−2 and 48.51 s−1, respectively. ► The apparent Michaelis–Menten constant (Kmapp) of the amperometric biosensor for the determination of H2O2 was 45.35 μM, which was markedly smaller than the value in the previous reports.
Co-reporter:X.N. Gu, N. Li, Y.F. Zheng, Liquan Ruan
Materials Science and Engineering: B 2011 Volume 176(Issue 20) pp:1778-1784
Publication Date(Web):15 December 2011
DOI:10.1016/j.mseb.2011.05.032
The feasibility of a Mg–Zn–Zr alloy for biomedical applications was studied through microstructure characterization, corrosion tests in different biological media, and cell proliferation, differentiation and adhesion tests. Corrosion tests showed that the ZK60 alloy in the as-extruded state with finer grain sizes exhibited slower corrosion rates than the same alloy in the as-cast state. The tests in different biological fluids showed that the corrosion rates of the as-cast and as-extruded ZK60 alloy in DMEM + FBS were the highest, while those in Hank's solution were the lowest. The corrosion rate of the as-extruded ZK60 alloy was similar to the corrosion rates of other commercial magnesium alloys, namely the die-cast AZ91D, die-cast AM50, extruded AZ31 and extruded WE43 alloys. The results obtained from the indirect cytotoxicity evaluation showed that the 100% concentrated cast and extruded ZK60 alloy extracts resulted in significantly reduced cell numbers and total protein amounts, as compared to the negative control. The cell number and total protein amount increased with the gradual dilution of the extracts, but the protein normalized ALP activity showed an opposite trend. For the direct assay, L-929 and MG63 cells exhibited good adhesion with spread pseudopod on the surface of extruded ZK60 alloy samples after 24 h culture. In short, the as-extruded ZK60 alloy could be a good candidate material for biodegradable implants.Highlights► The feasibility of Mg-Zn-Zr alloy as a potential biodegradable implants. ► As-extruded Mg-Zn-Zr alloy exhibits slower corrosion rate than the one in as-cast state. ► As-extruded Mg-Zn-Zr alloy shows comparable corrosion rate as other commercial Mg alloys for biomedical application. ► As-extruded Mg-Zn-Zr alloy shows good cytocompatibility.
Co-reporter:Yufeng Zheng;Xuenan Gu
JOM 2011 Volume 63( Issue 4) pp:105-108
Publication Date(Web):2011 April
DOI:10.1007/s11837-011-0049-7
The potential application of Mg alloys as bioabsorable/biodegradable implants have attracted much recent attention in China. Advances in the design and biocompatibility evaluation of bio-Mg alloys in China are reviewed in this paper. Bio-Mg alloys have been developed by alloying with the trace elements existing in human body, such as Mg-Ca, Mg-Zn and Mg-Si based systems. Additionally, novel structured Mg alloys such as porous, composited, nanocrystalline and bulk metallic glass alloys were tried. To control the biocorrosion rate of bio-Mg implant to match the self-healing/regeneration rate of the surrounding tissue in vivo, surface modification layers were coated with physical and chemical methods.
Co-reporter:X.N. Gu, N. Li, Y.F. Zheng, F. Kang, J.T. Wang, Liquan Ruan
Materials Science and Engineering: B 2011 Volume 176(Issue 20) pp:1802-1806
Publication Date(Web):15 December 2011
DOI:10.1016/j.mseb.2011.04.003
The equal channel angular pressing (ECAP) technique with and without back pressure (BP) was introduced in this paper to prepare biomedical AZ31 magnesium alloy, with the effect of pass number (from 1 to 4) on the corrosion properties as well as in vitro biocompatibility being investigated. The results indicated that ECAPed or BP-ECAPed AZ31 alloys exhibited similar corrosion rate to that of the as-extruded one, but the corrosion rate slightly increased after 1–2 passes ECAP or BP-ECAP and further decreased after 4-pass procedure. Additionally, severe local corrosion was observed for the 1–3 passes ECAPed or BP-ECAPed AZ31 alloy samples. Compared to the as-extruded AZ31 alloy, the samples after ECAP or BP-ECAP procedure showed much smaller sized corrosion pits on the surface after removing the corrosion product. The surface analysis after 20 days immersion in Hank's solution revealed that the composition of the corrosion product consisted of C, O, Mg, P, Ca whereas only weak signal of Mg(OH)2 could be detected beside the dominant α(Mg) peak by X-ray diffraction. The cytotoxicity results suggested that the multi-pass ECAPed or BP-ECAPed AZ31 alloy exhibited Grade I–II cytotoxicity according to ISO 10993-5: 1999.
Co-reporter:Y.J. Bai, Y.B. Wang, Y. Cheng, F. Deng, Y.F. Zheng, S.C. Wei
Materials Science and Engineering: C 2011 Volume 31(Issue 3) pp:702-711
Publication Date(Web):8 April 2011
DOI:10.1016/j.msec.2010.12.010
The corrosion behavior of Ti–Nb dental alloy in artificial saliva with and without the addition of lactic acid and sodium fluoride was investigated by electrochemical techniques, with the commercial Titanium–molybdenum alloy (TMA) as a comparison. The chemical composition, microstructure and constitutional phase were characterized via energy dispersive spectrometry, optical microscope and X-ray diffraction, meanwhile the open circuit potential, electrochemical impedance spectroscopy and potentiodynamic polarization measurements were carried out to study the corrosion resistance of experimental alloys, with the corroded surface being further characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. It was found that the corrosion behavior of Ti–Nb alloy was similar to those TMA alloy samples in both artificial and acidified saliva solutions, whereas statistical analysis of the electrochemical impedance spectroscopy and polarization parameters showed Ti–Nb alloy exhibited better corrosion resistance in fluoridated saliva and fluoridated acidified saliva. SEM observation indicated that TMA alloy corroded heavily than Ti–Nb alloy in fluoride containing saliva. XPS surface analysis suggested that Nb2O5 played an important role in anti-corrosion from the attack of fluoride ion. Based on the above finding, Ti–Nb alloy is believed to be suitable for the usage in certain fluoride treated dental works with excellent corrosion resistance in fluoride-containing oral media.
Co-reporter:Y.F. Zhang, Y.F. Zheng, L. Qin
Nanomedicine: Nanotechnology, Biology and Medicine 2011 Volume 7(Issue 6) pp:975-982
Publication Date(Web):December 2011
DOI:10.1016/j.nano.2011.04.005
Co-reporter:Jia Li;Wei Zheng;Xia Lou
Science China Life Sciences 2011 Volume 54( Issue 4) pp:366-371
Publication Date(Web):2011 April
DOI:10.1007/s11427-011-4155-0
The objective of this study was to investigate the hemocompatibility and cell responses to some novel poly(L-lactide) (PLA) composites containing surface modified hydroxyapatite particles for potential applications as a bone substitute material. The surface of hydroxyapatite (HA) particles was first grafted with L-lactic acid oligomers to form grafted HA (g-HA) particles. The g-HA particles were further blended with PLA to prepare g-HA/PLA composites. Our previous study has shown significant improvement in tensile properties of these materials due to the enhanced interfacial adhesion between the polymer matrix and HA particles. To further investigate the potential applications of these composites in bone repair and other orthopedic surgeries, a series of in vitro and in vivo experiments were conducted to examine the cell responses and hemocompatibility of the materials. In vitro experiments showed that the g-HA/PLA composites were well tolerated by the L-929 cells. Hemolysis of the composites was lower than that of pure PLA. Subcutaneous implantation demonstrated that the g-HA/PLA composites were more favorable than the control materials for soft tissue responses. The results suggested that the g-HA/PLA composites are promising and safe materials with potential applications in tissue engineering.
Co-reporter:X. N. Gu;X. Wang;N. Li;L. Li;Y. F. Zheng;Xigeng Miao
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2011 Volume 99B( Issue 1) pp:127-134
Publication Date(Web):
DOI:10.1002/jbm.b.31879
Abstract
In this article, a novel MgCa alloy-hydroxyapatite-tricalcium phosphate (HA/TCP) composite was fabricated using the liquid alloy infiltration technique. The feasibility of the composite for biomedical applications was studied through mechanical testing, electrochemical testing, immersion testing, and cell culture evaluation. It was shown that the composite had a strength about 200-fold higher than that of the original porous HA/TCP scaffold but retained half of the strength of the bulk MgCa alloy. The corrosion test indicated that the resulting composite exhibited an average corrosion rate of 0.029 mL cm−2 h−1 in the Hank's solution at 37°C, which was slower than that of the bulk MgCa alloy alone. The indirect cytotoxicity evaluation revealed that 100% concentrated (i.e., undiluted or as-collected) extract of the MgCa-HA/TCP composite showed significant toxicity to L-929 and MG63 cells (p < 0.05). In contrast, the diluted extracts with 50 and 10% concentrations of the MgCa-HA/TCP composite exhibited a similar degree of cell viability (p > 0.05), equivalent to the grade I cytotoxicity of the standard ISO 10993-5: 1999. © 2011 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Co-reporter:Y. B. Wang;Y. F. Zheng;S. C. Wei;M. Li
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2011 Volume 96B( Issue 1) pp:34-46
Publication Date(Web):
DOI:10.1002/jbm.b.31725
Abstract
With pure Ti and pure Zr as controls, the corrosion resistance, ion release behavior, and in vitro biocompatibility of Be-containing Zr41Ti14Cu12Ni10Be23 bulk metallic glass (BMG) (LM1), Zr44Ti11Cu10Ni10Be25 BMG (LM1b), and Be-free Zr57Nb5Cu15.4Ni12.6Al10 BMG (LM106) were investigated in terms of electrochemical measurements in simulated body fluid (SBF) with pH value 7.4 and artificial saliva (AS) with pH value 6.3, and 3-[4,4-dimethylthiazol-2-yl]-2,5-diphenyltetrazolium bromide (MTT) assay using L929 and NIH3T3 cells, aiming to assess the feasibility of Zr-based BMGs as potential biomaterial. It was found that LM1b showed superior corrosion resistance to LM106 and LM1 in both SBF and AS, and comparable with pure Ti and pure Zr. After 7200 s immersion, a two-layer structure oxide film was formed on LM1, LM1b, and pure Zr surfaces, while one-layer structure oxide film was formed on LM106 and pure Ti surfaces. The pitting corrosion potentials of LM1b were much higher than that of LM1, LM106, and pure Zr, resulting in very few ions releasing into the electrolytes. No Be ion could be detected but a little amount of Cu ion was detected for LM106, LM1, and LM1b after immersion in Dulbecco's modified Eagle's medium for 72 h at 37°C. The indirect cytotoxicity results show that LM106, LM1, and LM1b extracts had no cytotoxicity to L929 and NIH3T3 cells. The direct cytotoxicity results show that cells could adhere well on the Zr-based BMG surface as in pure Ti and Zr. Lower cell proliferation rate of LM106 and LM1 is observed when compared with LM1b, which was found to be caused by Cu ion releasing rather than by Be ion. © 2010 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2011.
Co-reporter:Y.F. Zheng, X.N. Gu, Y.L. Xi, D.L. Chai
Acta Biomaterialia 2010 Volume 6(Issue 5) pp:1783-1791
Publication Date(Web):May 2010
DOI:10.1016/j.actbio.2009.10.009
Abstract
Mg/Ca (1 wt.%, 5 wt.%, 10 wt.% Ca) composites were prepared from pure magnesium and calcium powders using the powder metallurgy method, aiming to enlarge the addition of Ca content without the formation of Mg2Ca. The microstructures, mechanical properties and cytotoxicities of Mg/Ca composite samples were investigated. The corrosion of Mg/Ca composites in Dulbecco’s modified Eagle’s medium (DMEM) for various immersion intervals was studied by electrochemical impedance spectroscopy measurements and environmental scanning electron microscope, with the concentrations of released Mg and Ca ions in DMEM for various immersion time intervals being measured. It was shown that the main constitutional phases were Mg and Ca, which were uniformly distributed in the Mg matrix. The ultimate tensile strength (UTS) and elongation of experimental composites decreased with increasing Ca content, and the UTS of Mg/1Ca composite was comparable with that of as-extruded Mg–1Ca alloy. The corrosion potential increased with increasing Ca content, whereas the current density and the impedance decreased. It was found that the protective surface film formed quickly at the initial immersion stage. With increasing immersion time, the surface film became compact, and the corrosion rate of Mg/Ca composites slowed down. The surface film consisted mainly of CaCO3, MgCO3·3H2O, HA and Mg(OH)2 after 72 h immersion in DMEM. Mg/1Ca and Mg/5Ca composite extracts had no significant toxicity (p > 0.05) to L-929 cells, whereas Mg/10Ca composite extract induced ∼40% reduced cell viability.
Co-reporter:X.N. Gu, W.R. Zhou, Y.F. Zheng, Y. Cheng, S.C. Wei, S.P. Zhong, T.F. Xi, L.J. Chen
Acta Biomaterialia 2010 Volume 6(Issue 12) pp:4605-4613
Publication Date(Web):December 2010
DOI:10.1016/j.actbio.2010.07.026
Abstract
Magnesium alloys have been recently developed as biodegradable implant materials, yet there has been no study concerning their corrosion fatigue properties under cyclic loading. In this study the die-cast AZ91D (A for aluminum 9%, Z for zinc 1% and D for a fourth phase) and extruded WE43 (W for yttrium 4%, E for rare earth mischmetal 3%) alloys were chosen to evaluate their fatigue and corrosion fatigue behaviors in simulated body fluid (SBF). The die-cast AZ91D alloy indicated a fatigue limit of 50 MPa at 107 cycles in air compared to 20 MPa at 106 cycles tested in SBF at 37 °C. A fatigue limit of 110 MPa at 107 cycles in air was observed for extruded WE43 alloy compared to 40 MPa at 107 cycles tested in SBF at 37 °C. The fatigue cracks initiated from the micropores when tested in air and from corrosion pits when tested in SBF, respectively. The overload zone of the extruded WE43 alloy exhibited a ductile fracture mode with deep dimples, in comparison to a brittle fracture mode for the die-cast AZ91D. The corrosion rate of the two experimental alloys increased under cyclic loading compared to that in the static immersion test.
Co-reporter:W. Zheng, H.Y. Zhao, J.X. Zhang, H.M. Zhou, X.X. Xu, Y.F. Zheng, Y.B. Wang, Y. Cheng, B.Z. Jang
Electrochemistry Communications 2010 Volume 12(Issue 7) pp:869-871
Publication Date(Web):July 2010
DOI:10.1016/j.elecom.2010.04.006
This study demonstrated a novel nanographene platelets (NGPs)-based glucose/O2 biofuel cell (BFC) with the glucose oxidase (GOD) as the anodic biocatalysts and the laccase as the cathodic biocatalysts. The GOD/NGPs-modified electrode exhibited good catalytic activity towards glucose oxidation and the laccase/NGPs-modified electrode exhibited good catalytic activity towards O2 electroreduction. The maximum power density was ca. 57.8 μW cm− 2 for the assembled glucose/O2 NGPs-based BFC. These results indicated that the NGPs were very useful for the future development of novel carbon-based nanomaterials BFC device.
Co-reporter:B. Tian, F. Chen, Y.X. Tong, L. Li, Y.F. Zheng, Y. Liu
Journal of Alloys and Compounds 2010 Volume 505(Issue 2) pp:680-684
Publication Date(Web):3 September 2010
DOI:10.1016/j.jallcom.2010.06.113
This study investigated the transformation strains of Ni–Mn–Ga polycrystalline alloy and Ni–Mn–Ga/epoxy resin composites. For the Ni–Mn–Ga polycrystalline alloy, the columnar grains formed along the solidification direction, and the alloy expanded during martensitic transformation in the direction with a transformation strain of ∼500 ppm. For the composite consisting of randomly distributed Ni–Mn–Ga particles, no transformation strain was achieved due to the random distribution of the Ni–Mn–Ga particles. For the composite consisting of properly oriented Ni–Mn–Ga particles, the martensitic transformation strains were found to be orientation-dependent, the shrinking transformation strain-c (parallel to the direction of magnetic field used during curing) up to ∼210 ppm was detected, and the expanding transformation strain-a (vertical to the direction of magnetic field used during curing) was measured to be ∼150 ppm.
Co-reporter:M.H. Ding, B.L. Wang, L. Li, Y.F. Zheng
Applied Surface Science 2010 Volume 257(Issue 3) pp:696-703
Publication Date(Web):15 November 2010
DOI:10.1016/j.apsusc.2010.07.026
Abstract
In this paper, TaxC1−x coatings were deposited on 316L stainless steel (316L SS) by radio-frequency (RF) magnetron sputtering at various substrate temperatures (Ts) in order to improve its corrosion resistance and hemocompatibility. XRD results indicated that Ts could significantly change the microstructure of TaxC1−x coatings. When Ts was <150 °C, the TaxC1−x coatings were in amorphous condition, whereas when Ts was ≥150 °C, TaC phase was formed, exhibiting in the form of particulates with the crystallite sizes of about 15–25 nm (Ts = 300 °C). Atomic force microscope (AFM) results showed that with the increase of Ts, the root-mean-square (RMS) values of the TaxC1−x coatings decreased. The nano-indentation experiments indicated that the TaxC1−x coating deposited at 300 °C had a higher hardness and modulus. The scratch test results demonstrated that TaxC1−x coatings deposited above 150 °C exhibited good adhesion performance. Tribology tests results demonstrated that TaxC1−x coatings exhibited excellent wear resistance. The results of potentiodynamic polarization showed that the corrosion resistance of the 316L SS was improved significantly because of the deposited TaxC1−x coatings. The platelet adhesion test results indicated that the TaxC1−x coatings deposited at Ts of 150 °C and 300 °C possessed better hemocompatibility than the coating deposited at Ts of 25 °C. Additionally, the hemocompatibility of the TaxC1−x coating on the 316L SS was found to be influenced by its surface roughness, hydrophilicity and the surface energy.
Co-reporter:F.L. Nie, Y.F. Zheng, Y. Cheng, S.C. Wei, R.Z. Valiev
Materials Letters 2010 Volume 64(Issue 8) pp:983-986
Publication Date(Web):30 April 2010
DOI:10.1016/j.matlet.2010.01.081
Bulk nanocrystalline and amorphous Ni50.2Ti49.8 alloy samples were successfully prepared from commercial microcrystalline Ni50.2Ti49.8 alloy discs by high pressure torsion (HPT) technique. Then their corrosion resistance, surface wettability and cytotoxicity were further studied from the viewpoint of biomaterials. In both Hank's solution and artificial saliva, bulk nanocrystalline and amorphous Ni50.2Ti49.8 alloys showed significantly higher pitting corrosion potentials than that of microcrystalline Ni50.2Ti49.8 alloy. Meanwhile, the amount of Ni ion release after immersion in Hank's solution was minor, far below the threatening threshold of daily diet. Murine fibroblast and osteoblast cell lines were indirectly co-cultured with experimental sample extracts, indicating no cytotoxicity. Amongst all samples, the nanocrystalline Ni50.2Ti49.8 shows promising as best biomaterial candidate for its good combination of mechanical property, corrosion resistance and cytocompatibility.
Co-reporter:H.F. Li, Y.B. Wang, Y. Cheng, Y.F. Zheng
Materials Letters 2010 Volume 64(Issue 13) pp:1462-1464
Publication Date(Web):15 July 2010
DOI:10.1016/j.matlet.2010.03.060
Three kinds of new barrier films were introduced on the surface of Ca60Mg15Zn25 bulk metallic glasses (BMGs) in order to slow down its biodegradation/corrosion rate, including fluoroalkylsilane (FAS) coating, pure Fe film and (Fe + FAS) bilayer. The changes of surface morphology were characterized by scanning electron microscopy (SEM). Contact angle meter was applied to test the surface wettability at ambient temperature. The corrosion rate was investigated by immersion test in deionized water. It was found that various micro-nanoscale hierarchical structures could be constructed after different surface treatments. By suitable surface modification strategy, Ca60Mg15Zn25 BMG showed increased water contact angle even up to 133.6°. The immersion experiment results showed that Fe film and FAS thin film coatings with hydrophobic and insulative characteristics are beneficial to provide effective anti-corrosive protection to Ca60Mg15Zn25 BMG, with the sequence: Fe coating > (Fe + FAS) treated > FAS treated.
Co-reporter:X.X. Xu, F.L. Nie, J.X. Zhang, W. Zheng, Y.F. Zheng, C. Hu, G. Yang
Materials Letters 2010 Volume 64(Issue 4) pp:524-527
Publication Date(Web):28 February 2010
DOI:10.1016/j.matlet.2009.11.065
Ultra-fine grained (UFG) bulk pure copper has been successfully fabricated by equal-channel angular pressing (ECAP), with the grain size about 380 nm after 8 passes. The potentiodynamic polarization results of the ECAP copper specimens tested in Hanks solution revealed that the corrosion current of UFG copper is higher than that of the coarse grained copper. The cupric ion release behaviors of UFG copper immersed in Hanks solution for 30 days only displayed a burst release during the first 3 days (in comparison to the 1–2 months for the conventional Cu) from 115 μg/day to 12.5 μg/day, after which the ion release remained constant and slow. During the immersion experiments, Cu2O was the only corrosion product found on the surface and it took 10 days or so to form a uniform Cu2O layer. Uniform corrosive damage on the surface and few localized corrosion is observed. The above results indicate that UFG copper could have high potential as biomedical materials for contraception.
Co-reporter:X.N. Gu, W.R. Zhou, Y.F. Zheng, Y. Liu, Y.X. Li
Materials Letters 2010 Volume 64(Issue 17) pp:1871-1874
Publication Date(Web):15 September 2010
DOI:10.1016/j.matlet.2010.06.015
The lotus-type porous pure magnesium was prepared using a metal/gas eutectic unidirectional solidification method (GASAR process). The corrosion behavior, decay of mechanical property and the cytocompatibility were evaluated with the compact pure Mg as control. The porous pure Mg indicates better corrosion resistance than that of compact pure Mg in SBF at 37 °C. The compressive yield strength of compact and porous pure Mg is (110.3 ± 8.5) MPa and (23.9 ± 4.9) MPa before immersion test, and porous pure Mg exhibits slower decay in compressive yield strength with the extension of immersion period than that of compact pure Mg. With larger exposed surface area, porous pure Mg shows higher Mg concentration in the extract than that of compact pure Mg, which leads to a higher osmotic pressure to cells and might affect its indirect cytotoxicity assay result, but is still within the Grade I RGR value (no toxicity), implying the feasibility as potential tissue engineering scaffold.
Co-reporter:Xuenan Gu, Yufeng Zheng, Shengping Zhong, Tingfei Xi, Junqiang Wang, Weihua Wang
Biomaterials 2010 31(6) pp: 1093-1103
Publication Date(Web):
DOI:10.1016/j.biomaterials.2009.11.015
Co-reporter:M.H. Ding, B.L. Wang, L. Li, Y.F. Zheng
Surface and Coatings Technology 2010 204(16–17) pp: 2519-2526
Publication Date(Web):
DOI:10.1016/j.surfcoat.2010.01.028
Co-reporter:Xuenan Gu, Weirui Zhou, Yufeng Zheng, Limin Dong, Yulin Xi, Donglang Chai
Materials Science and Engineering: C 2010 30(6) pp: 827-832
Publication Date(Web):
DOI:10.1016/j.msec.2010.03.016
Co-reporter:Z.X. Meng, W. Zheng, L. Li, Y.F. Zheng
Materials Science and Engineering: C 2010 30(7) pp: 1014-1021
Publication Date(Web):
DOI:10.1016/j.msec.2010.05.003
Co-reporter:X.N. Gu, W. Zheng, Y. Cheng, Y.F. Zheng
Acta Biomaterialia 2009 Volume 5(Issue 7) pp:2790-2799
Publication Date(Web):September 2009
DOI:10.1016/j.actbio.2009.01.048
Abstract
To reduce the biocorrosion rate by surface modification, Mg–Ca alloy (1.4 wt.% Ca content) was soaked in three alkaline solutions (Na2HPO4, Na2CO3 and NaHCO3) for 24 h, respectively, and subsequently heat treated at 773 K for 12 h. Scanning electron microscopy and energy-dispersive spectroscopy results revealed that magnesium oxide layers with the thickness of about 13, 9 and 26 μm were formed on the surfaces of Mg–Ca alloy after the above different alkaline heat treatments. Atomic force microscopy showed that the surfaces of Mg–Ca alloy samples became rough after three alkaline heat treatments. The in vitro corrosion tests in simulated body fluid indicated that the corrosion rates of Mg–Ca alloy were effectively decreased after alkaline heat treatments, with the following sequence: NaHCO3 heated < Na2HPO4 heated < Na2CO3 heated. The cytotoxicity evaluation revealed that none of the alkaline heat treated Mg–Ca alloy samples induced toxicity to L-929 cells during 7 days culture.
Co-reporter:Y.B. Wang, H.F. Li, Y. Cheng, S.C. Wei, Y.F. Zheng
Electrochemistry Communications 2009 Volume 11(Issue 11) pp:2187-2190
Publication Date(Web):November 2009
DOI:10.1016/j.elecom.2009.09.027
The corrosion performance of a Nickel-free Fe-based bulk metallic glass (BMG), Fe41Co7Cr15Mo14C15B6Y2 alloy, in Hank’s solution with pH value 7.4 and artificial saliva solution with pH value 6.3, was investigated by electrochemical techniques, aiming to assess the feasibility of Fe-based BMG as potential biomaterial. It was found that Fe41Co7Cr15Mo14C15B6Y2 BMG shows superior corrosion resistance in both simulated body fluids (SBF). The EIS analysis and cyclic polarization measurements indicated that the Fe41Co7Cr15Mo14C15B6Y2 BMG has larger polarization resistance value than that of 316L SS. The pitting corrosion potentials of Fe41Co7Cr15Mo14C15B6Y2 BMG are much higher than that of the 316L SS, resulting in very few ions releasing into the SBFs while a significant amount of Ni and Fe ions release was found for 316L SS under the same condition.
Co-reporter:Y.B. Wang, Y.F. Zheng
Materials Letters 2009 Volume 63(Issue 15) pp:1293-1295
Publication Date(Web):15 June 2009
DOI:10.1016/j.matlet.2009.02.062
With CP Ti sample as control, the electrochemical measurements were used to investigate the corrosion resistance of low modulus Ti16Nb shape memory alloy in Hank's solution with pH value 7.4. The OCP curves show that the passive film on the Ti16Nb alloy surface is quite stable. The tafel plots and anodic polarization curves prove that the Ti16Nb alloy has excellent anti-corrosion properties in Hank's solution, which is even better than that of CP Ti. The XPS analysis reveals that the composition of the oxide film on Ti16Nb alloy is mainly TiO2 and Nb2O5. The indirect cytotoxicity results prove that Ti16Nb alloy has an excellent biocompatibility as CP Ti with high proliferation rate approaching that of the negative control group.
Co-reporter:H.Y. Zhao, H.M. Zhou, J.X. Zhang, W. Zheng, Y.F. Zheng
Biosensors and Bioelectronics 2009 Volume 25(Issue 2) pp:463-468
Publication Date(Web):15 October 2009
DOI:10.1016/j.bios.2009.08.005
This study demonstrates a novel carbon nanotubes-hydroxyapatite (CNTs–HA) nanocomposite-based compartment-less glucose/O2 biofuel cell (BFC) with the glucose oxidase (GOD) as the anodic biocatalysts and the laccase as the cathodic biocatalysts. CNTs–HA nanocomposite prepared by the self-assembly method via an aqueous solution reaction has been used as the co-immobilization matrix to incorporate biocatalysts, i.e. GOD and laccase successfully. Moreover, the three-dimensional configuration of the CNTs–HA films electrode would be advantageous to the glucose oxidation on the bioanode and O2 electroreduction on the biocathode of BFC. The maximum power density delivered by the assembled glucose/O2 BFC could reach 15.8 μW cm−2 at a cell voltage of 0.28 V with 10 mM glucose. The results indicate that the CNTs–HA nanocomposite is believed to be very useful for the development of novel BFC device.
Co-reporter:Y.F. Zheng, D. Liu, X.L. Liu, L. Li
Applied Surface Science 2008 Volume 255(Issue 2) pp:512-514
Publication Date(Web):15 November 2008
DOI:10.1016/j.apsusc.2008.06.116
Abstract
Zirconium film was prepared on TiNi alloy by plasma immersion ion implantation and deposition (PIIID) technique to enhance its corrosion resistance and prolong its working lifetime. The atomic force microscopy (AFM) results show that the film was relatively smooth with the root mean square roughness being 9.166 nm. The X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD) results indicate that the implant element of Zr was oxidation partialness. The potentiodynamic polarization measurements in the Hank's solution at 37 °C show that the corrosion resistance of the alloy was improved by the Zr coating film and the atomic absorption spectrometry (AAS) tests also indicate that Ni ion concentration released from the substrate in the Hank's solution after the polarization test was reduced greatly, in comparison to the unmodified TiNi alloy sample.
Co-reporter:J. Li, X.L.Lu, Y.F. Zheng
Applied Surface Science 2008 Volume 255(Issue 2) pp:494-497
Publication Date(Web):15 November 2008
DOI:10.1016/j.apsusc.2008.06.067
Abstract
In this study, we modified the surface of hydroxyapatite (HA) particle by ring-opening polymerization of lactide (LA). The modified HA particles were characterized by IR and TGA. It was shown that LA could be graft-polymerized onto the surface of HA. A series of composites based on modified HA/PLA were further prepared and characterized. It indicated that the modified HA particles were well dispersed in PLA matrix than unmodified HA particles and the adhesion between HA particle and PLA matrix was improved. The modified HA/PLA composites showed good mechanical properties than that of unmodified HA/PLA.
Co-reporter:W. Zheng, Y.Q. Chen, Y.F. Zheng
Applied Surface Science 2008 Volume 255(Issue 2) pp:571-573
Publication Date(Web):15 November 2008
DOI:10.1016/j.apsusc.2008.06.096
Abstract
This study describes the noncovalently functionalization of carbon nanotubes (CNTs) with natural biopolymer chitosan (Chi) as substrate for hemoglobin (Hb) immobilization. The noncovalently Chi-functionalized CNTs possessed an improved solubility in aqueous solution and was beneficial to form three-dimensional configuration of the CNTs film electrode. The adsorbed Hb in Chi-CNTs interface showed a pair of quasi-reversible redox peak with a formal potential of −0.34 V (vs. SCE) in 0.10 M pH 7.0 phosphate buffer solution and possessed good bioelectrochemical catalytic activities toward the reductions of H2O2.
Co-reporter:W. Zheng, J. Li, Y.F. Zheng
Journal of Electroanalytical Chemistry 2008 Volume 621(Issue 1) pp:69-74
Publication Date(Web):1 September 2008
DOI:10.1016/j.jelechem.2008.04.014
Biocompatible poly(l-lactide) (PLA) was synthesized by a lactide monomer polymerization, with the structure be confirmed by FT-IR spectrum. The direct electrochemistry and electrocatalytic properties of Hemoglobin (Hb) and PLA co-assembled film (Hb-PLA film) cast on glass carbon (GC) electrode were investigated. A pair of well-defined redox peaks of Hb with a formal potential (E0′) of about −0.38 V (vs. SCE) in a pH 7.0 phosphate buffer solution (PBS) were obtained at the Hb-PLA film modified GC electrode. The apparent heterogeneous electron transfer rate constant (ks) was evaluated to be 42.3 s−1 by the Laviron’s equation. The surface concentration (Γ∗) of the electroactive Hb in the PLA film was estimated to be 4.39 × 10−11 mol cm−2. Moreover, the Hb entrapped in PLA film showed good bioelectrocatalytic activity for the electrochemical reduction of H2O2. The amperometric response varied linearly with the H2O2 concentration ranged from 10 μM to 120 μM, with a detection limit of 12.3 × 10−6 M and a high stability of the immobilized Hb in PLA film. Finally, we applied this proposed method to investigate the concentration of H2O2 in real samples.
Co-reporter:W. Zheng, H.M. Zhou, Y.F. Zheng, N. Wang
Chemical Physics Letters 2008 Volume 457(4–6) pp:381-385
Publication Date(Web):27 May 2008
DOI:10.1016/j.cplett.2008.04.047
Abstract
Direct electron transfer between laccase and a glassy carbon electrode modified with carbon nanotubes having a uniform inner tube diameter was observed by cyclic voltammetry in 0.10 M phosphate buffer. The formal potential of +530 mV (vs. SCE) was very close to redox potential of T1 copper in laccase. No direct electron transfer between laccase and a glassy carbon electrode modified with carbon nanotubes having a tapered inner tube diameter was determined under the same condition. The possible application of the laccase-catalyzed O2 reduction at these electrodes was successfully illustrated by constructing an ascorbate/O2 biofuel cell.
Co-reporter:B. Tian, F. Chen, Y. Liu, Y.F. Zheng
Materials Letters 2008 Volume 62(17–18) pp:2851-2854
Publication Date(Web):30 June 2008
DOI:10.1016/j.matlet.2008.01.071
The Ni49.8Mn28.5Ga21.7 powders of micro-scale irregular equiaxial particles are prepared by ball milling method, and characterized by XRD, DSC and SEM techniques. The powders are found to contain disordered fct structure. Upon heating to high temperatures, the crystal structure of the as-milled powder is found to evolve from disordered fct to disordered bcc and then to a Heusler-type structure sequentially. The critical temperature for the transition from the bcc phase to the Heusler phase is 360 °C. This phase transition process is also a disorder–order transition. An atomic ordering model similar to the grain nucleation and growth is established to explain the annealing temperature dependence of the phase transformation temperature.
Co-reporter:Y.G. Song, W.S. Li, L. Li, Y.F. Zheng
Materials Letters 2008 Volume 62(Issue 15) pp:2325-2328
Publication Date(Web):31 May 2008
DOI:10.1016/j.matlet.2007.11.082
The Nd:YAG laser welding was used to join the binary NiTi alloy wires with different compositions(Ti–50.0 at.%Ni and Ti–50.9 at.%Ni) which had the same diameter of 1 mm. The wires were welded with different parameters, including impulse width and welding current. The aim was to assess the influence of the laser-welding process on the microstructure and mechanical properties of the welded joint of binary NiTi wires. The optical microscopy (OM) and the metallographic microscopy (MM) were used to analyze the microstructure of the welded joints. The tensile test and the differential scanning calorimetry (DSC) were carried out to examine the ultimate tensile strength and the reverse martensitic transformation temperatures of the welded joints. It was found that the welding current and the impulse width had great influence on the quality of the welded joints, an optimal parameter combination would remove the pores and micro-cracks appeared in the fusion zone, and result in good mechanical properties such as higher fracture strength and elongation. The laser welding had a few effect on the reverse martensitic transformation temperatures of the welded joints.
Co-reporter:Y.B. Wang, Y.F. Zheng
Materials Letters 2008 Volume 62(Issue 2) pp:269-272
Publication Date(Web):31 January 2008
DOI:10.1016/j.matlet.2007.05.038
The microstructure, phase composition, mechanical properties and shape memory effect of the Ti–16 at.%Nb alloy were investigated by means of TEM, XRD, bending test and tensile test. The XRD results showed that the Ti–16 at.%Nb alloy is mainly composed of two phases: α″ phase and β phase at room temperature. TEM observation proved that there is also a little amount of ω phase in the Ti–16 at.%Nb alloy solid solution treated at 750 °C for 0.5 h. The martensite lath with a sub-structure of (111) type I twin was found in the Ti–16 at.%Nb alloy solid solution treated at 750 °C for 0.5 h by TEM observation. While solid solution treated at 750 °C, the Ti–16 at.%Nb alloy has the best combination of mechanical properties. The Ti–16 at.%Nb alloy has a certain shape memory effect. When the pre-strain is less than 2%, the deformed alloy can completely recover to the original shape. The SME of the Ti–16 at.%Nb alloy has an acceptable reproducibility, because when pre-deformed with 3.26% strain, after more than 20 times deformation cycling, the recovery ratio is still more than 40%.
Co-reporter:W. Zheng, J. Li, Y.F. Zheng
Biosensors and Bioelectronics 2008 Volume 23(Issue 10) pp:1562-1566
Publication Date(Web):15 May 2008
DOI:10.1016/j.bios.2008.01.002
In this study, poly(ɛ-caprolactone) (PCL) was synthesized using the ɛ-caprolactone (CL) monomer ring-opening polymerization. We demonstrated that the hemoglobin (Hb) entrapped in PCL film could retain its original conformation by FT-IR spectra. A pair of well-defined redox peaks with a formal potential (E0′)(E0′) of about −0.38 V (vs. SCE) in a pH 7.0 phosphate buffer solution was obtained at the Hb–PCL film modified GC electrode. The dependence of E0′E0′ on the pH of the buffer solution indicated that the conversion of heme Fe(III)/Fe(II) was a reaction of one electron coupled to one proton. The apparent heterogeneous electron transfer rate constants (ks) of Hb confined to PCL was evaluated as (18.7 ± 0.8) s−1 according to Laviron's equation. The surface concentration (Γ*) of the electroactive Hb in the PCL film was estimated to be (7.27 ± 0.57) × 10−11 mol cm−2. The Hb–PCL film modified electrode was shown to be an excellent amperometric sensor for the detection of hydrogen peroxide. The linear range is from 2 to 30 μM with a detection limit of 6.07 × 10−6 M. The sensor was effectively testified by the determination of the hydrogen peroxide in eyedrops as real samples.
Co-reporter:B. Tian, F. Chen, Y. Liu, Y.F. Zheng
Intermetallics 2008 Volume 16(11–12) pp:1279-1284
Publication Date(Web):November–December 2008
DOI:10.1016/j.intermet.2008.08.002
The transformation and magnetic properties of Ni49.8Mn28.5Ga21.7 powders produced by ball milling and post-milling annealing were investigated in this study. It was found that ball milling suppresses both the Curie transition and the Heusler ↔ tetragonal martensitic phase transformation of the alloy. Ball milling also severely weakens the magnetization of the alloy. Annealing at elevated temperatures is effective in restoring the ferromagnetism and the martensitic transformation of the alloy. The suppression of the Curie transition is attributed to atomic disordering caused by ball milling. The suppression of the martensitic transformation is attributed to severe structural deformation as well as atomic disordering induced by the ball milling.
Co-reporter:W. Zheng, Y.F. Zheng, K.W. Jin, N. Wang
Talanta 2008 Volume 74(Issue 5) pp:1414-1419
Publication Date(Web):15 February 2008
DOI:10.1016/j.talanta.2007.09.017
Titanium oxide nanotubes (TiO2-NTs) synthesized by the hydrothermal method had been prepared as the co-immobilization matrix to incorporate hemoglobin (Hb) successfully. The nanostructures of TiO2-NTs were investigated by X-ray diffraction and high-resolution electron microscopy. The Hb immobilized in TiO2-NTs had a similar structure to the native of Hb and retained its near-native conformations as characterized by the UV–vis and FT-IR spectroscopy. A couple of quasi-reversible redox peaks with a formal potential of −0.34 V (vs. SCE) in 0.10 M pH 7.0 phosphate buffered saline (PBS) were observed. The amperometric response of the immobilized Hb linearly to H2O2 concentration ranged from 4 μM to 64 μM with a detection limit of 4.637 × 10−6 M and the high stability of the immobilized Hb in TiO2-NTs constituted a promising platform for the development of biosensors.
Co-reporter:Y.-F. Zheng;Q. Y. Wang;L. Li
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2008 Volume 86B( Issue 2) pp:335-340
Publication Date(Web):
DOI:10.1002/jbm.b.31023
Abstract
The aim of this study was to investigate the electrochemical behavior of Ti49.6Ni45.1Cu5Cr0.3 (TiNiCuCr) alloy in artificial saliva solutions with a wide rage of pH values and to characterize the surface passive film after polarization tests. This article represents the ideal, static environment and associated electrochemical response and comparison values. The corrosion behavior of TiNiCuCr alloy was systematically studied by open circuit potential, potentiodynamic, potentiostatic, and electrochemical impedance techniques. Potentiodynamic and potentiostatic test results showed that the corrosion behavior of TiNiCuCr was similar to that of NiTi alloy. Both corrosion potential (Ecorr) and pitting corrosion potential (Eb) showed a pH-dependent tendency that Ecorr and Eb decreased with the increase of the pH value. X-ray photoelectron spectroscopy results revealed the composition of the passive film consisted mainly of TiO2 with a little amount of Ni oxides (NiO/Ni2O3) that was identical with NiTi alloy. Besides Ni, a Cu enriched sub-layer was also found. The nickel ion release rate showed a typical time-related decrease as examined by ICP/OES. In conclusion, the addition of Cu and Cr had little effect on the corrosion behavior of NiTi or on the composition and the structure of the passive film. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 2008
Co-reporter:W. Zheng, Y.F. Zheng
Electrochemistry Communications 2007 Volume 9(Issue 7) pp:1619-1623
Publication Date(Web):July 2007
DOI:10.1016/j.elecom.2007.03.007
In this paper, we compared the use of gelatin-functionalized carbon nanotubes (CNTs) as substrates for Hemoglobin (Hb) immobilization and as electrodes for electrochemical reduction of the absorbed Hb. The non-covalently gelatin-functionalized CNTs possessed an improved solubility in aqueous solution and may have an enhanced biocompatibility with Hb. The characteristics of Hb/gelatin-CNTs composite films were studied by using UV–vis spectroscopy, FTIR spectroscopy and electrochemical methods. The immobilized Hb showed a couple of quasi-reversible redox peaks with a formal potential of −0.35 V (vs. SCE) in 0.10 M pH 7.0 phosphate buffer solution (PBS). The surface concentration of electroactive Hb immobilized on gelatin-CNT/GC electrode was about 4.34 × 10−10 mol cm−2.
Co-reporter:C. Li, Y.F. Zheng
Materials Letters 2006 Volume 60(13–14) pp:1646-1650
Publication Date(Web):June 2006
DOI:10.1016/j.matlet.2005.11.097
The corrosion performance of Ti50Ni47Fe3 alloy in 0.9% NaCl physiological, artificial saliva and Hank's solutions with different pH values at 37 °C was investigated by means of open circuit potential (OCP) measurement and linear polarization (LP) measurement techniques, respectively. The OCP stabilized at − 0.2925, − 0.3111 and − 0.3454 mV/SCE in sequence for 0.9% NaCl, artificial saliva and Hank's solutions, respectively. LP results demonstrated that the Ti50Ni47Fe3 alloy has a low passive current and a wide passive range. The surface roughness and in-depth distribution of the passive films after immersion in corrosion media was characterized by using Atomic Force Measurement (AFM) and X-ray electron spectroscopy (XPS). AFM results shows that the electrochemical measurements have little influence on the surface roughness of the Ti50Ni47Fe3 alloy, and the XPS analysis results revealed that the outer passive film consisting mainly of a layer of TiO2 which is deemed to be important for all biomaterials.
Co-reporter:Y. Cheng, Y.F. Zheng
Surface and Coatings Technology 2006 Volume 200(14–15) pp:4543-4548
Publication Date(Web):10 April 2006
DOI:10.1016/j.surfcoat.2005.03.039
Diamond-like carbon (DLC) films have been successfully deposited on Ti–50.8 at.% Ni alloys using plasma based ion implantation (PBII) technique. The influence of the pulsed negative bias voltage applied to the substrate from 12 eV to 40 eV on the surface characteristics and corrosion resistant property as well as hemocompatibility has been investigated. The results show that the RMS values firstly decrease from 7.202 nm (12 kV) to 5.279 nm (20 kV), and then increase to 6.991 nm (30 kV) and 7.060 nm (40 kV). With the voltage increasing the value of I(D)/I(G) ratio firstly decreases, and reaches a minimum value at 20 kV, and then increases. Combined with the Tafel measurement and SEM observation, we found that the uncoated TiNi alloy shows severe pitting corrosion, which could be due to the presence of Cl− ions in the solution. On the contrary, the coated sample shows very little pitting corrosion and behaves with better corrosion resistant property especially for the specimens deposited at 20 kV bias voltages. The platelet adhesion test shows that the hemocompatibility of DLC coated TiNi alloy is much better than that of the bare TiNi alloy, and the hemocompatibility performance of DLC coated TiNi alloy deposited at 20 kV is superior to that of the other coated specimens.
Co-reporter:
Science 1920 Vol 51(1307) pp:60
Publication Date(Web):16 Jan 1920
DOI:10.1126/science.51.1307.60
Co-reporter:
Science 1919 Vol 49(1273) pp:492-495
Publication Date(Web):23 May 1919
DOI:10.1126/science.49.1273.492
Co-reporter:Yufeng Zheng
Bioactive Materials (September 2016) Volume 1(Issue 1) pp:1
Publication Date(Web):September 2016
DOI:10.1016/j.bioactmat.2016.09.003
Co-reporter:Liang Liu, Huafang Zhang, Xingeng Lei, Yufeng Zheng
Physics Procedia (2011) Volume 18() pp:206-210
Publication Date(Web):1 January 2011
DOI:10.1016/j.phpro.2011.06.082
EB-PVD TBCs were deposited at nearly the same process parameters but substrate rotation speed to investigate the effect of rotation adjustment on microstructure and thermal conductivity. The microstructure was checked by scanning electron microscopy (SEM) and the thermal conductivity was calculated on the basis of determination of thermal diffusivity by laser flash method. The results showed the stationary deposition formed most dense coating and increasing rotation speed resulted in wider columnar grains and enlarged shadowing effect which meant much more volume of pores. The density and thermal conductivity at room temperature both decreased with increasing rotation speed. The lowest experimental value, 1.37 W/mK, was obtained for a 171 μm thick free-standing coating, when the rotation speed was 20 rpm in this study.
Co-reporter:J.L. Xu, Q.F. Xiao, D.D. Mei, Z.C. Zhong, Y.X. Tong, Y.F. Zheng, L. Li
Journal of Magnetism and Magnetic Materials (15 March 2017) Volume 426() pp:361-368
Publication Date(Web):15 March 2017
DOI:10.1016/j.jmmm.2016.11.105
•Amorphous SiO2 coatings were prepared on sintered NdFeB magnets by micro-arc oxidation.•The coatings presented excellent thermal shock resistance.•The corrosion resistance could be enhanced by one order of magnitude.•The MAO coatings slightly decreased the magnetic properties of the NdFeB samples.Amorphous SiO2 coatings were prepared on sintered NdFeB magnets by micro-arc oxidation (MAO) in silicate solution. The surface and cross-sectional morphologies, element and phase composition, corrosion resistance and magnetic properties of the coatings were investigated by scanning electron microscopy (SEM), energy dispersive X-ray spectrometer (EDS), X-ray photoelectron spectroscopy (XPS), potentiodynamic polarization test and physical properties measurements system (PPMS). The results showed that the surface morphologies of the coatings exhibited the “coral reef” like structure, different from the typical MAO porous structure. With increasing the voltages, the thickness of the coatings increased from 12.72 to 19.90 µm, the content of Si element increased, while the contents of Fe, Nd and P elements decreased. The coatings were mainly composed of amorphous SiO2 and a few amorphous Fe2O3 and Nd2O3. The amorphous SiO2 coatings presented excellent thermal shock resistance, while the thermal shock resistance decreased with increasing the voltages. The corrosion resistance of the coatings increased with increasing the voltages, and it could be enhanced by one order of magnitude compared to the uncoated NdFeB magnets. The MAO coatings slightly decreased the magnetic properties of the NdFeB samples in different degrees.
Co-reporter:Guanping He, Yuanhao Wu, Yu Zhang, Ye Zhu, Yang Liu, Nan Li, Mei Li, Guan Zheng, Baohua He, Qingshui Yin, Yufeng Zheng and Chuanbin Mao
Journal of Materials Chemistry A 2015 - vol. 3(Issue 32) pp:NaN6689-6689
Publication Date(Web):2015/07/27
DOI:10.1039/C5TB01319D
Most of the magnesium (Mg) alloys possess excellent biocompatibility, mechanical properties and biodegradability in orthopedic applications. However, these alloys may suffer from bacterial infections due to their insufficient antibacterial capability. In order to reduce the post-surgical infections, a series of biocompatible Mg–1Ca–0.5Sr–xZn (x = 0, 2, 4, 6) alloys were fabricated with the addition of antibacterial Zn with variable contents and evaluated in terms of their biocompatibility and antibacterial properties. The in vitro corrosion study showed that Mg–1Ca–0.5Sr–6Zn alloys exhibited a higher hydrogen evolution volume after 100 h immersion and resulted in a higher pH value of the immersion solution. Our work indicated that Zn-containing Mg alloys exhibited good biocompatibility with high cell viability. The antibacterial studies reveal that the number of bacteria adhered on all of these Mg alloy samples diminished remarkably compared to the Ti–6Al–4V control group. We also found that the proliferation of the bacteria was inhibited by these Mg alloy extracts. Among the prepared alloys, the Mg–1Ca–0.5Sr–6Zn alloy not only exhibited a strong antibacterial effect, but also promoted the proliferation of MC3T3-E1 osteoblasts, suggesting that it is a promising alloy with both good antibacterial properties and good biocompatibility for use as an orthopedic implant.
