Co-reporter:Shuping Wu, Jiao Hu, Liuting Wei, Yumin Du, Xiaowen Shi, Lina Zhang
Food Chemistry 2014 Volume 148() pp:196-203
Publication Date(Web):1 April 2014
DOI:10.1016/j.foodchem.2013.10.044
•MRPs from four model systems were prepared.•MRPs were studied by UV–Vis spectra and biological activity.•MRPs had similar infrared spectra and molecular structures.•MRPs of xylan with chitosan showed the highest radical scavenging activity.•Glucosamine hydrochloride had good antibacterial activity against microorganisms.The structure, UV absorbance, browning intensity, fluorescence changes, antioxidant activity and antimicrobial assessment of Maillard reaction products (MRPs) derived from xylan with chitosan, chitooligomer, glucosamine hydrochloride and taurine model systems were evaluated. The results revealed that all MRPs had similar infrared spectra and molecular structures. MRPs from different model systems on the UV absorbance at 294 nm after heated 90 min and browning intensity at 420 nm showed the similar law: xylan-taurine > xylan-glucosamine hydrochloride > xylan-chitooligomer > xylan-chitosan, and the order of DPPH scavenging activity of MRPs was as follows: xylan-chitosan > xylan-chitooligomer > xylan-glucosamine hydrochloride > xylan-taurine, which revealed that the properties of MRPs were closely related to molecular weight of model systems. Moreover, the highest radical scavenging activity of MRPs from xylan with chitosan/chitooligomer/glucosamine hydrochloride/taurine model systems was 65.9%, 63.7%, 46.4% and 42.5%, respectively.
Co-reporter:Xiaoxia Li, Xiaowen Shi, Yong Jin, Fuyuan Ding, Yumin Du
Carbohydrate Polymers 2013 Volume 91(Issue 1) pp:428-433
Publication Date(Web):2 January 2013
DOI:10.1016/j.carbpol.2012.08.052
Controllable antioxidative xylan–chitosan Maillard reaction products (MRPs) were prepared by co-heating xylan and chitosan at different time periods and used for lipid food storage in lecithin model system and refrigerated pork meat. The results of antioxidant protective effect on lecithin liposome peroxidation induced by 2,2′-azobis(2-methylpropionamidine) dihydrochloride revealed that the MRPs heated for 120 min and 180 min showed much higher inhibitory activity than chitosan or MRP heated for 60 min. In the experiment of fresh pork protection, the MRPs heated for 60 and 120 min retarded the growth of spoilage organisms more effectively. Lipid oxidation potential of the meat, determined by thiobarbituric acid reactive substances, also showed that the samples treated by the MRPs heated for 60 and 120 min had higher acceptance than others. These results demonstrate that the MRPs of xylan and chitosan are promising controllable antioxidative preservatives for lipid food formulations, and the antioxidant behavior depends not only on the antioxidant substances, but also on the interaction of the food systems.Highlights► The xylan–chitosan MRPs tended to protect the peroxidation of lecithin liposome induced by AAPH. ► Fresh pork treated by the early xylan–chitosan MRPs retarded lipid oxidation and microbial spoilage during refrigerated storage. ► The antioxidant behavior of MRPs depended not only on the antioxidant substances, but also on the interaction of the food systems.
Co-reporter:Shuping Wu, Yumin Du, Yunzi Hu, Xiaowen Shi, Lina Zhang
Food Chemistry 2013 Volume 138(2–3) pp:1312-1319
Publication Date(Web):1 June 2013
DOI:10.1016/j.foodchem.2012.10.118
In this study, a ternary complex based on natural polysaccharides was explored as a novel food preservative. Chitooligomer was obtained by enzyme hydrolysis of chitosan with immobilised neutral protease, and the degree of polymerisation (DP) was mainly from 2 to 5. Chitooligomer–zinc complex (CGZC) was first produced and then co-heated with xylan to prepare xylan–chitooligomer–zinc complex (XCGZC). XCGZC showed higher antioxidant and antibacterial activity than chitooligomer, chitooligomer–zinc and xylan–chitooligomer. The IC50 of XCGZC was 5.37 mg/mL, which was equal to the antioxidant ability of 3.28 mg/mL BHT. The diameter of the inhibition zone for XCGZC against Escherichia coli and Staphylococcus aureus was 17.2 ± 0.4 and 30.3 ± 0.6 mm vs. control of 6.0 mm. Besides, XCGZC had excellent antibacterial activity against Bacillus subtilis, Salmonella typhimurium, Bacillus megaterium. Therefore, XCGZC can be used as a novel promising preservative with antibacterial and antioxidant properties in the food industry.Highlights► We prepared xylan–chitooligomer–zinc complex by Maillard reaction. ► The complex showed excellent antioxidant activity. ► The complex had good antibacterial activity against Escherichia coli and Staphylococcus aureus.
Co-reporter:Shangjing Xin, Yuejun Li, Wei Li, Jing Du, Rong Huang, Yumin Du, Hongbing Deng
Carbohydrate Polymers 2012 Volume 90(Issue 2) pp:1069-1074
Publication Date(Web):1 October 2012
DOI:10.1016/j.carbpol.2012.06.045
In this study, carboxymethyl chitin (CMC) - organic rectorite (OREC)/poly (vinyl alcohol) (PVA) composite nanofibrous mats were successfully prepared via electrospinning. SAXRD pattern showed that the interlayer distance of OREC was increased from 3.68 to 4.08 nm, which verified that polymer chains were intercalated into the interlayer of OREC. Field emission scanning electron microscopy, Fourier transform infrared spectra and energy-dispersive X-ray spectroscopy were used to characterize the morphology and microcosmic structure of nanofibrous mats. Thermal properties of mats were determined by differential scanning calorimetry. To evaluate the cell compatibility of mats, mouse lung fibroblast (L929) was chosen for cell attachment and spreading assay. The results shows that nanofibrous mats contained OREC have better thermal properties. Besides, the addition of OREC has little effect on the cell compatibility of nanofibrous mats.Highlights► Electrospun carboxymethyl chitin/organic rectorite nanofibrous mats. ► Characterize the morphology and elements of the composite mats. ► Study the thermal properties of the as-spun mats. ► Investigate the cell compatibility of the nanofibrous mats.
Co-reporter:Jin Li, Jun Cai, Lian Zhong, Yumin Du
Carbohydrate Polymers 2012 Volume 87(Issue 4) pp:2697-2705
Publication Date(Web):1 March 2012
DOI:10.1016/j.carbpol.2011.11.062
Neutral protease was immobilized on chitosan (CS), carboxymethyl chitosan (CMCS), and N-succinyl chitosan (NSCS) hydrogel beads. And the biocatalysts obtained were used to prepare low molecular weight chitosan (LMWC) and chitooligomers. Weight-average molecular weight of LMWC produced by neutral protease immobilized on CS, CMCS and NSCS hydrogel beads were 3.4 kDa, 3.2 kDa and 1.9 kDa, respectively. The effects of immobilization support and substrate on enzymatic reaction were analyzed by measuring classical Michaelis–Menten kinetic parameters. The FT-IR, XRD and potentiometric determination results indicated decrease of molecular weight led to transformation of crystal structure, but the degree of N-deacetylation and chemical structures of residues were not changed compared to initial chitosan. The degree of polymerization of chitooligomers was mainly from 2 to 7. We observed a strong dependence of the immobilized enzyme properties on the chemical nature of the supports, which leads to different microenvironment of neutral protease and changes the hydrolyzing process.Highlights► Chitosaneous hydrogel beads were used as immobilization support. ► Neutral protease immobilized on different immobilization support results in different hydrolysis process. ► Low molecular weight chitosan prepared by neutral protease immobilized on different support shows different physicochemical properties.
Co-reporter:Xiaohui Wang, Dong Li, Yanzhu Guo, Xiaoying Wang, Yumin Du, Runcang Sun
Optical Materials 2012 Volume 34(Issue 4) pp:646-651
Publication Date(Web):February 2012
DOI:10.1016/j.optmat.2011.09.013
Employing a biomimic method using polysaccharide as template, luminescent lanthanide ions doped CdS and ZnS quantum dots (QDs) were prepared. According to the results of TEM and absorbance, nanocrystals with an average size of 6 nm were formed under mild condition without any toxic and expensive agent applied. Differentiating from the un-doped CdS and ZnS QDs prepared in polysaccharide template, the lanthanide doped QDs exhibited obvious dopant emission in their photoluminescence spectrum. It was also found that the dopant PL became more prominent with increasing lanthanide doping concentration, while the highest PL intensity was obtained at a doping level of 1% for both of CdS and ZnS QDs. When different lanthanide ions were introduced into the CdS QDs in polysaccharide template, varied emission wavelength were able to be obtained. This study provides an easy, mild and environmental friendly alternative method to prepare doped quantum dots. In addition, the bioactivity and processabilities endowed by the polysaccharide template may expand the applications potential of this type of optical materials.Highlights► Luminescent lanthanide doped CdS and ZnS quantum dots are prepared in polysaccharide template. ► The doped quantum dots have controllable size. ► The nanocomposites have impurity doping concentration related photoluminescence. ► This nanocomposite is good candidate for extended applications.
Co-reporter:Xianwen Hu, Yufeng Tang, Qun Wang, Yan Li, Jianhong Yang, Yumin Du, John F. Kennedy
Carbohydrate Polymers 2011 Volume 83(Issue 3) pp:1128-1133
Publication Date(Web):30 January 2011
DOI:10.1016/j.carbpol.2010.09.014
The rheological behaviour of chitin in 8 wt% NaOH/4 wt% urea aqueous medium was evaluated by steady shear and dynamic oscillatory tests, in which the effects of concentration, temperature and time on the rheological behaviour of chitin aqueous solution were investigated in detail. It suggested that chitin aqueous solution is sensitive to temperature, which will transform to a gel when temperature increases to physiological conditions. And the higher the concentration is, the lower the gelation temperature is. The comparison on rheological behaviour of chitin aqueous solution at different time reveals that 8 wt% NaOH/4 wt% urea solvent at low temperature has little effect on chitin structure. It is interesting that the chitin gel has reversibility and it will transit to solution after being treated at low temperature again. The comparison on rheological behaviour between the original chitin aqueous solution and the chitin aqueous solution after gelation reveals that gelation has a little effects on solution properties.
Co-reporter:Xiaoxia Li, Xueyong Li, Beilei Ke, Xiaowen Shi, Yumin Du
Carbohydrate Polymers 2011 Volume 85(Issue 4) pp:747-752
Publication Date(Web):1 July 2011
DOI:10.1016/j.carbpol.2011.03.040
We prepared chitosan/chitin whisker/rectorite ternary films and studied the cooperative effects of nanofibril whisker and layered organic rectorite on the properties of chitosan matrix. The ternary film exhibited higher thermal stability and smoother surface than the whisker or rectorite reinforced binary films due to the intercalation of chitosan chains into the layered rectorite and the impregnation between the clay and rod-like whisker. With increasing the ratio of mixed fillers from 0 to 229 mg/g, the break elongation first increased to a maximum value (144%) with the mixed fillers of 114.5 mg/g and then decreased. Antimicrobial assay against Escherichia coli and Staphylococcus aureus showed that the ternary films had higher antimicrobial effect than the pure or binary films because of the significant adsorption capacities of the enlarged interlayer of rectorite. Overall, the chitosan-based ternary film with chitin whisker and rectorite proves to be a suitable material for food-packaging applications.
Co-reporter:Hongbing Deng, Xiaoying Wang, Pu Liu, Bin Ding, Yumin Du, Guoxiang Li, Xianwen Hu, Jianhong Yang
Carbohydrate Polymers 2011 Volume 83(Issue 1) pp:239-245
Publication Date(Web):1 January 2011
DOI:10.1016/j.carbpol.2010.07.042
Organic rectorite (OREC) was used to prepare the intercalated composites with chitosan (CS). The negatively charged cellulose nanofibers hydrolyzed from electrospun cellulose acetate fibrous mats were modified with multilayers of the positively charged CS-OREC intercalated composite and the negatively charged sodium alginate (ALG) via layer-by-layer (LBL) technique. The morphology and antibacterial activity of the resultant samples were studied by regulating the number of deposition bilayers, the compositions of dipping solutions and outermost layer of films. Field emission scanning electron microscopy images indicated that the thickness of CS-OREC/ALG bilayer formed on fibers was estimated from 12 to 26 nm. Additionally, the energy-dispersive X-ray spectroscopy and X-ray photoelectron spectroscopy results indicated that CS and OREC were successfully deposited on cellulose fibers. The bacterial inhibition experiments demonstrated that LBL films modified fibrous cellulose mats with the addition of OREC can increase the degree of inhibition on Escherichia coli.
Co-reporter:Hongbing Deng, Xueyong Li, Bin Ding, Yumin Du, Guoxiang Li, Jianhong Yang, Xianwen Hu
Carbohydrate Polymers 2011 Volume 83(Issue 2) pp:973-978
Publication Date(Web):10 January 2011
DOI:10.1016/j.carbpol.2010.09.008
A uniform electrospun nanofibrous membrane was fabricated from chitosan (CS)–polyvinyl alcohol (PVA)/organic rectorite (OREC) with different mixing ratios by solution-mixing process and eleltrospinning technologies. The morphology, intercalation between polymer and OREC, and bacterial inhibition activity of the electrospun membranes were investigated. Field emission scanning electron microscopy showed uniform fibrous structure generated with the addition of OREC. Energy-dispersive X-ray spectroscopy results confirmed the existence of OREC on the surface of electrospun membranes. Fourier transform infrared spectra and small angle X-ray diffraction results verified that the interlayer of OREC was intercalated by CS and PVA chains successfully. The controllable interlayer distance of OREC was enlarged from 3.68 to 4.28 nm. The membranes had enhanced bacterial inhibition activity with the addition of OREC.
Co-reporter:Xiaoxia Li, Xiaowen Shi, Miao Wang, Yumin Du
Food Chemistry 2011 Volume 126(Issue 2) pp:520-525
Publication Date(Web):15 May 2011
DOI:10.1016/j.foodchem.2010.11.037
Xylan, a hemicellulose extracted from corn cobs, was co-heated with chitosan to prepare a polysaccharide-based food preservative. UV absorbance, browning and fluorescence changes indicated the presence of Maillard reaction between the two reactants. Antioxidant capacities, including 2,2-diphenyl-1-picrylhydrazyl (DPPH·) radical-scavenging activity and reducing power, showed that the xylan-chitosan conjugates possessed excellent antioxidant activity depending on the heating time while chitosan or xylan alone did not possess any. The antimicrobial activity of the conjugates against Escherichia coli and Staphylococcus aureus was higher than chitosan. These results indicated that the Maillard reaction conjugate of xylan and chitosan was a promising preservative for various food formulations to enhance microbial safety and extend shelf life.Research highlights► A novel conjugate based on xylan and chitosan was prepared. ► Maillard reaction occurred between the natural polysaccharides. ► The conjugate was endowed with high antioxidant and antibacterial activities. ► The conjugate can be used as the food preservation.
Co-reporter:Guoxiang Li, Yumin Du, Yongzhen Tao, Yating Liu, Sheng Li, Xianwen Hu, Jianhong Yang
Carbohydrate Polymers 2010 Volume 80(Issue 3) pp:970-976
Publication Date(Web):5 May 2010
DOI:10.1016/j.carbpol.2010.01.014
Four kinds of natural chitin originating from crab (C1), shrimp (C2), silkworm chrysalis (C3) and flies shell (C4) were dissolved in 8 wt.% NaOH/4 wt.% urea aqueous solution. Dilute solution behavior of chitin was examined by laser light scattering and viscometry. The Mark–Houwink equation and the relationship between the z-average radius of gyration (Rg) and the average-weight molecular (Mw) for C1 in the solvent at 25 °C were determined to be [η] = 0.26Mw0.56±0.02 (mL g−1) and Rg = 0.15Mw0.47±0.03 (nm), respectively. On the basis of the polymer solution theory, the conformation parameters of C1 to C4 samples were calculated to be in the range of 25–18 nm for the length of the Kuhn statistical segment (Qk), and 43–32 for the characteristic ratio (C∞), respectively. It indicated that chitin molecules existed in a random-coil chain conformation, and chain flexibility increases from C1 to C4 in NaOH/urea aqueous system.
Co-reporter:Yufeng Tang, Xiaoying Wang, Yan Li, Ming Lei, Yumin Du, John F. Kennedy, Charles J. Knill
Carbohydrate Polymers 2010 Volume 82(Issue 3) pp:833-841
Publication Date(Web):15 October 2010
DOI:10.1016/j.carbpol.2010.06.003
The properties of an injectable chitosan (CS)/methylcellulose (MC) blend hydrogel used as a three-dimensional synthetic matrix for tissue engineering were investigated. CS/MC hydrogels were prepared via blending of CS, MC and salts under mild conditions without organic solvent, high temperature or harsh pH. Such blends were liquid at low temperature (∼4 °C), but gel under physiological conditions (37 °C). The effect of different salts including NaCl, Na3PO4, NaHCO3 and glycerophosphate (GP) on the CS/MC gelation process was investigated by rheological analysis from which possible gelation mechanisms were inferred. Viscoelastic characteristics indicated that CS/MC gels formed using different salts had different gelation temperature, gelation rate, and gel strength. Gelation temperature followed the order NaCl > GP > Na3PO4 > NaHCO3, gelation rate followed the order GP > NaHCO3 > Na3PO4, and gel strength followed the order GP > NaHCO3 > Na3PO4 (at 37 °C).CS/MC hydrogels were also characterised by infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), and X-ray diffraction (XRD). CS/MS gels formed with different salts had different gel structures, ranging from nonporous to microporous. When used as a scaffold for chondrocytes, CS/MC/Na3PO4 hydrogel resulted in good cell viability and proliferation.
Co-reporter:Hongbing Deng, Xue Zhou, Xiaoying Wang, Chunyan Zhang, Bin Ding, Qiuhua Zhang, Yumin Du
Carbohydrate Polymers 2010 Volume 80(Issue 2) pp:474-479
Publication Date(Web):12 April 2010
DOI:10.1016/j.carbpol.2009.12.004
For the first time, a novel fibrous polysaccharide scaffold for cell culture was fabricated by the combination of electrospinning and electrostatic layer-by-layer (LBL) self-assembly technique. Oppositely charged chitosan (CS) and alginate (ALG) in aqueous media were alternatively deposited onto the negatively charged cellulose nanofibrous mats which hydrolyzed from electrospun cellulose acetate mats. The morphology and biocompatibility of the resultant scaffolds were investigated by regulating the pH of dipping solutions, the number of deposition bilayers, and the composition of outermost layer. Field emission scanning electron microscopy images indicated that the scaffolds possessed the fibrous structure and the thickness of CS/ALG bilayer formed on fibers was estimated in the range of 8–15 nm. The X-ray photoelectron spectroscopy results verified the existence of nitrogen element of CS on the surface of LBL films. The cell culture experiments demonstrated that the scaffolds have good biocompatibility for Beas-2B human bronchial epithelial cells in vitro.
Co-reporter:Baofeng Lin, Yumin Du, Yanming Li, Xingquan Liang, Xiaoying Wang, Wen Deng, Xiaohui Wang, Lei Li, John F. Kennedy
Carbohydrate Polymers 2010 Volume 81(Issue 3) pp:554-559
Publication Date(Web):7 July 2010
DOI:10.1016/j.carbpol.2010.03.006
The starch-based composite material (STM) was prepared with cassava starch and modified cellulose and coated with chitosan to obtain better hydrophobic and heat-resistant properties. The hydrogen bond interactions between chitosan and basic material were proven by FTIR. By the SEM analysis, the blends showed a good compatibility and the cavities in STM was repaired and smoothed after coating. From the results of polarized optical microscope, AFM and positron annihilation lifetime spectroscopy, coating the STM with chitosan decreased the free volume of uncoated STM after moist heat treatment, the amorphous regions of the latter absorbed water more easily than the former. The mechanical properties of uncoated STM were inferior to the coated STM. Furthermore, chitosan coating decreased the gain weight and slowed the dissolution rate of starch. This study shows chitosan coating could enhance the water barrier and heat-resistant properties of STM.
Co-reporter:Guoxiang Li, Yumin Du, Yongzhen Tao, Hongbing Deng, Xiaogang Luo, Jianhong Yang
Carbohydrate Polymers 2010 Volume 82(Issue 3) pp:706-713
Publication Date(Web):15 October 2010
DOI:10.1016/j.carbpol.2010.05.040
Chitin/alginate magnetic nano-gel beads (MCAs) were successfully prepared from 8 wt.% NaOH/4 wt.% urea aqueous solution by ionic cross-linking. Their structure and properties were investigated using scanning electron microscopy, X-ray diffraction, and vibrating sample magnetometry. The results showed that the magnetic iron oxide nanoparticles synthesized in situ with a mean diameter of 30 nm were uniformly dispersed and immobilized in the chitin/alginate matrix. The structure and nature of iron oxide were conserved perfectly, and the MCAs had extremely small hysteresis loop and low coercivity. Moreover, MCAs could efficiently adsorb the methyl orange from wastewater. The iron oxide nanoparticles in the MCAs played an important role in both the creation of the magnetic-induced transference and the improvement of the adsorption capacity. This work provides a novel, low-cost, simple, and “green” process for synthesizing the chitin-based magnetic nanocomposite gel beads, which had potential application on the removal of hazardous materials.
Co-reporter:Yufeng Tang;Yiyang Zhao;Yan Li
Polymer Bulletin 2010 Volume 64( Issue 8) pp:791-804
Publication Date(Web):2010 May
DOI:10.1007/s00289-009-0214-0
The synthesis and characterization of a thermosensitive chitosan (CS)/poly(vinyl alcohol) (PVA) hydrogel containing nanoparticles with different charges for drug delivery were reported. Through the electrostatic effect of –N+(CH3)3 and –COO−, the nanoparticles of N-(2-hydroxyl) propyl-3-trimethyl ammonium chitosan chloride(HTCC)–carboxymethyl chitosan (CM) were prepared. The nanoparticles with different charges were obtained by the different ratio of –N+(CH3)3 and –COO−, which were suitable for drug delivery with opposite charges, such as propranolol and diclofenac sodium, respectively. The release of the positive drug was the slowest with the hydrogels containing negative nanoparticles. Similarly, the release of the negative drug was the slowest with the hydrogels containing positive nanoparticles. However, the releases of the two drugs were both the fastest with the pure hydrogels. It indicated the addition of nanoparticles was helpful to slow the suitable drug release. Though the nanoparticles did not reinforce the gel strength, the electrostatic effect between nanoparticles and drugs reduced the burst release. Therefore, the composite gels are attractive for applications as carriers for drug delivery.
Co-reporter:Qun Wang, Xianwen Hu, Yumin Du, John F. Kennedy
Carbohydrate Polymers 2010 82(3) pp: 842-847
Publication Date(Web):
DOI:10.1016/j.carbpol.2010.06.004
Co-reporter:Xiaoying Wang, Yumin Du, Jiwen Luo, Jianhong Yang, Weiping Wang, John F. Kennedy
Carbohydrate Polymers 2009 Volume 77(Issue 3) pp:449-456
Publication Date(Web):11 July 2009
DOI:10.1016/j.carbpol.2009.01.015
Rectorite (REC), a type of layered silicate, was used to prepare the intercalated nanocomposites with quaternized chitosan (HTCC). Characterization by XRD and TEM revealed that HTCC were intercalated into the intergallery of REC. Moreover, it was confirmed from FT-IR, XRD and ζ-potential analyses that interaction between HTCC and REC took place. Two in vitro antimicrobial assays indicated that all the nanocomposites exhibited strong inhibition against Gram-positive bacteria, Gram-negative bacteria and Fungi under weak acid, water and weak basic condition, particularly against Gram-positive bacteria. Moreover, with increasing the amount or the interlayer distance of organic REC, the antimicrobial activity was stronger. The lowest minimum inhibition concentration values of the nanocomposites against Staphylococcus aureus and Bacillus subtilis were less than 0.00313% (w/v) in all media tested, and the killing rate on S. aureus reached more than 90% in 30 min. The mechanism of the antimicrobial action was briefly discussed.
Co-reporter:Ying Hu;Xiaoying Wang;Tao Feng
Journal of Biomedical Materials Research Part A 2009 Volume 90A( Issue 3) pp:874-881
Publication Date(Web):
DOI:10.1002/jbm.a.31871
Abstract
Water-soluble chitosan (WCS) with five different molecular weights was synthesized by N-acetylation of chitosan with acetic anhydride. Degree of deacetylation of sample was determined by potentiometric titration. The structure of WCS was characterized by FTIR, XRD, and gel permeation chromatography. The critical aggregation concentration (cac) of self-aggregation was determined by measuring the fluorescence intensity of pyrene as a fluorescent probe and the surface tension. With the decrease of weight-average molecular weight (Mw), the cac values of WCSs in aqueous media were 0.48, 0.41, 0.35, 0.16, and 0.06 mg/mL, respectively. The surface tension–concentration plots of WCS5 had more than one turning point. It showed WCS had tendency to form monomolecular micelles in the very dilute solutions. In addition, WCSs were evaluated for efficacy of nanoparticle formation, which can solubilize and carry thymol, a water-insoluble antimicrobial agent. The diameter and morphology of thymol-loaded WCS nanoparticles were characterized by Zeta size nano series and TEM. Mean diameters of these thymol-loaded WCS nanoparticles in aqueous media were 189, 167, 134, 35, and 21 nm, respectively. TEM photographs exhibited the thymol-loaded WCS nanoparticle as a bimolecular micelle. Furthermore, thymol-loaded WCS nanoparticles had stronger antibacterial activity than thymol. With the decrease of the size, the thymol-loaded nanoparticles showed a stronger antimicrobial effect on gram-positive bacteria and fungi. The minimum inhibitory concentration value of thymol-loaded WCS5 nanoparticle against Staphyococcus aureus and Bacillus subtilis was 0.00313–0.00157% (w/v). © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Co-reporter:Yufeng Tang;Yan Li;Xiaoying Wang;Xianwen Hu
Journal of Biomedical Materials Research Part A 2009 Volume 91A( Issue 4) pp:953-963
Publication Date(Web):
DOI:10.1002/jbm.a.32240
Abstract
The synthesis and characterization of a thermosensitive chitosan/poly(vinyl alcohol) (PVA) hydrogel containing hydroxyapatite for protein delivery were first reported. Two synthetic processes were introduced, that is, in situ and ex situ routes. Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), scanning electron microscopy (SEM), and rheological analysis were employed to characterize the hydrogel. The gel formation decreased the crystallinity of the hydroxyapatite crystal. FTIR results showed that the hydroxyapatite crystals were partially substituted by carbonate. It was supposed that the structural features of hydroxyapatite were close to those of biological apatites. The thermosensitive property of the gels was evaluated by rheological analysis, which indicated that the strength of hydroxyapatite–chitosan/PVA composite gels was notably enhanced in comparison with that of pure chitosan/PVA gel, especially for hydroxyapatite–chitosan/PVA composite gels synthesized through the in situ process. The performances of composite gels containing different amounts of hydroxyapatite were further studied. For the hydroxyapatite–chitosan/PVA composite gels containing 0.1 mM hydroxyapatite synthesized through in situ process, the swelling degree was the lowest, and the speed of protein release was the slowest. Therefore, the composite gels are attractive for applications as protein delivery, artificial bones, and scaffolds for tissue engineering. © 2008 Wiley Periodicals, Inc. J Biomed Mater Res, 2009
Co-reporter:Yan Li;Yufeng Tang;Xiaoying Wang
Polymer International 2009 Volume 58( Issue 10) pp:1120-1125
Publication Date(Web):
DOI:10.1002/pi.2639
Abstract
BACKGROUND: Blended hydrogels are widely applied in medical fields. They can provide many advantages, such as biocompatibility and biodegradability. Many materials and methods are used to obtain blended hydrogels. In this work, carboxymethyl chitosan (CMCS) and poly(vinyl alcohol) (PVA) blended hydrogels were prepared using the freezing and thawing technique. The properties of the hydrogels prepared, i.e. gel fraction, swelling and pH-responsive behaviors, were investigated.
RESULTS: The gel fraction increased with increasing time of freezing and thawing as determined through gravimetric analysis. It was also found that the equilibrium degree of swelling improved obviously due to the addition of CMCS compared to pure PVA hydrogel. The blended hydrogel with composition CMCS/PVA 80/20 (by weight) possessed the highest swelling ratio. The results of the influence of pH values on the swelling behavior showed that minimum swelling ratios of the hydrogels occurred near the isoelectric point of CMCS. Protein release studies were performed under various pH conditions: the release was much slower under acid than under basic conditions. The release showed a burst in the first 15 h and then steadily increased.
CONCLUSION: The addition of CMCS can improve the physical properties of pure PVA hydrogels and provide pH sensitivity. It is concluded that PVA hydrogels containing CMCS could be potentially applied as oral delivery systems for protein drugs. Copyright © 2009 Society of Chemical Industry
Co-reporter:Yan Li;Chang Zou
European Food Research and Technology 2009 Volume 228( Issue 6) pp:
Publication Date(Web):2009 April
DOI:10.1007/s00217-009-1014-3
In order to study the effects of environmental conditions, antioxidant and antimicrobial activities of tea saponins (TS) in different pH values were evaluated. The antioxidant activity was examined by reducing power, superoxidant radical scavenging activity, metal chelating activity and so on. Antimicrobial activity was investigated using gram-negative, gram-positive bacterial and fungi. In vitro antioxidant activities exhibited pH dependency, and increased with increasing concentration of the extract. When pH was 8.0, TSs showed the best antioxidant activities, while the reversal result was found in antimicrobial measurement. At pH 8.0 and concentration 2.0 mg/mL, TSs scavenged 90.5% of superoxide radical. At pH 4.8, the minimum inhibitory concentration of TS was lower than 0.00625 % (w/v). The results indicate that TS can be an ideal antioxidant, and its antioxidant and antimicrobial activity depend on pH values.
Co-reporter:Weiping Wang, Yumin Du, Yanlin Qiu, Xiaoying Wang, Ying Hu, Jianhong Yang, Jun Cai, John F. Kennedy
Carbohydrate Polymers 2008 Volume 74(Issue 1) pp:127-132
Publication Date(Web):1 October 2008
DOI:10.1016/j.carbpol.2008.01.025
Low molecular weight chitosan (LMW-chitosan) in the molecular range 5–10 kDa was firstly prepared directly from the Absidia coerulea mycelia. To improve the LMW-chitosan production, the solid-state fermentation media were optimized to investigate the influence of substrate and supplemental medium components on LMW-chitosan production. The LMW-chitosan was obtained after treatments with 2% NaOH and 10% acetic acid. Maximal LMW-chitosan production was 6.12 g/kg substrate. Gel permeation chromatography combined with laser light scattering gave a Mw of 6.4 kDa with Mw/Mn of 1.09. FT-IR, X-ray diffraction and 13 C NMR spectra of the product showed typical peak distributions the same as those of standard chitosan which confirmed the extracted product to be chitosan-like. The method provided a new, simple and green technology to produce LMW-chitosan directly.
Co-reporter:Tao Feng, Yumin Du, Jin Li, Ying Hu, John F. Kennedy
Carbohydrate Polymers 2008 Volume 73(Issue 1) pp:126-132
Publication Date(Web):4 July 2008
DOI:10.1016/j.carbpol.2007.11.003
Chitosan was irradiated in acetic acid solution (1%) with different doses (2–20 kGy) of Co-60 γ rays to investigate the enhancement of antioxidant activity of irradiated chitosan. The structure of irradiation degraded chitosan was characterized by GPC, FT-IR and 1H NMR spectroscopy. The molecular weight of chitosan decreased with increasing irradiation dose. Radical mediated lipid peroxidation inhibition, reducing power, superoxide anion radical and hydroxyl radical quenching assays were used for the evaluation of the antioxidant activity of irradiated chitosan. Chitosan (Mw 2.1 × 103) which had been irradiated at 20 kGy exhibited high reductive capacity and expressed good inhibition of linoleic acid peroxidation. At a concentrtion of 0.1 mg/mL it could scavenge 74.2% of superoxide radical. At 2.5 mg/mL, scavenging percentage of chitosan irradiated for 0, 2, 10, 20 kGy against hydroxyl radical was 16.6%, 41.1%, 47.1% and 63.8%, respectively. The results show that γ ray irradiation, especially for 20 kGy, of chitosan gives enough degradation to increase its antioxidant activity as a result of a change in molecular weight.
Co-reporter:Chang Zou, Yumin Du, Yan Li, Jianhong Yang, Tao Feng, Le Zhang, John F. Kennedy
Carbohydrate Polymers 2008 Volume 73(Issue 2) pp:322-331
Publication Date(Web):19 July 2008
DOI:10.1016/j.carbpol.2007.11.035
Lacquer polysaccharide (LP) was isolated and purified from the sap of the lac tree (Rhus vernicifera). Five sulfated lacquer polysaccharide (LPS), with various molecular weights (Mw) and degrees of sulfation (DS) were prepared by the reaction of LP with sulfur trioxide–pyridine complex (SO3·Py) in DMSO. The structure of LPS was analyzed by GPC, UV–vis, FT-IR and 13C NMR spectroscopy; the Mw of LPS was in the range of 0.78–1.58 × 104, DS varied from 0.22 to 0.58, and unsaturated bond presence was observed by FT-IR. Antioxidant assays showed that LPS antioxidant activities were related to Mw, DS and unsaturated bond presence. One LPS, with moderate Mw and DS, showed the best antioxidant capacities, its reducing capacity was 0.61 at 500 μg/mL, scavenging ability for superoxide and hydroxyl radical were 56.4% at 500 μg/mL, 55.6% at 1000 μg/mL, respectively. The data obtained in in vitro models establish the antioxidant potential of LPS for application in pharmaceuticals. The LPS may be a promising antioxidant in vitro.
Co-reporter:Qun Wang;Na Zhang;Xianwen Hu;Jianhong Yang
Journal of Biomedical Materials Research Part A 2008 Volume 85A( Issue 4) pp:881-887
Publication Date(Web):
DOI:10.1002/jbm.a.31544
Abstract
Fibers of chitosan and polyethylene glycol (PEG), with salicylic acid as model drug incorporated in different concentrations, were obtained by spinning their solution through a viscose-type spinneret into a coagulating bath containing aqueous tripolyphosphate and ethanol. Chemical, morphological, and mechanical properties characterization were carried out, as well as the studies of the factors that influence the drug releasing from chitosan/PEG fibers. These factors included the component ratio of chitosan and PEG, the loaded amount of salicylic acid, the pH and the ionic strength of the release solution and others. The diameter of the fibers is around 15 ± 3 μm. The best values of the tensile strength at 12.86 cN/tex and breaking elongation at 21.13% of blend fibers were obtained when the PEG content was 8 and 5 wt %, respectively; the water-retention value of blend fibers increased as the composition of PEG was raised. The results of controlled release tests showed that the amount of salicylic acid released increased with an increase in the proportion of PEG present in the fiber. Moreover, the release rate of drug decreased as the amount of drug loaded in the fiber increased, but the cumulative release amount is increasing. The chitosan/PEG fibers were also sensitive to pH and ionic strength. The release rate was being accelerated by a lower pH and a higher ionic strength, respectively. All the results indicated that the chitosan/PEG fiber was potentially useful in drug delivery systems. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Co-reporter:Xiaoying Wang;Jianhong Yang;Yufeng Tang ;Jiwen Luo
Journal of Biomedical Materials Research Part A 2008 Volume 84A( Issue 2) pp:384-390
Publication Date(Web):
DOI:10.1002/jbm.a.31326
Abstract
Quaternized chitosan/layered silicate nanocomposite was prepared by simple solution-mixing in aqueous media. Montmorillonite (MMT) modified with cetyltrimethyl ammonium bromide was used as an organically modified layered silicate. XRD and TEM analyses respectively confirmed that silicate layers of MMT were intercalated and nicely distributed in quaternized chitosan matrix in despite of the high content of MMT (25–50 wt %). The interactions between the quaternized chitosan macromolecules and MMT in aqueous media were analyzed using FTIR, XRD, and ζ-potential measurements. Antimicrobial studies showed that the nanocomposites could strongly inhibit the growth of a wide variety of microorganisms, including Gram-positive bacteria, Gram-negative bacteria, and fungi; more importantly, they exhibited good antimicrobial capacity in whichever medium, in weak acid, water, or weak base. As the amount of MMT increased, the nanocomposites had better inhibitory effect on microorganisms, especially Gram-positive bacteria. The lowest minimum inhibition concentration (MIC) value of the nanocomposites against Staphylococcus aureus and Bacillus subtilis were less than 0.00313% (w/v) under all the conditions. The adsorption action of MMT on bacteria was simply discussed via SEM images. The results revealed that the strong antimicrobial of the nanocomposites may be attributed to the fine dispersion and the interaction between quaternized chitosan and MMT. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2008
Co-reporter:Xiaoying Wang, Yumin Du, Jiwen Luo, Baofeng Lin, John F. Kennedy
Carbohydrate Polymers 2007 Volume 69(Issue 1) pp:41-49
Publication Date(Web):1 May 2007
DOI:10.1016/j.carbpol.2006.08.025
Rectorite is a kind of layered silicate, with the structure and characteristic much like those of montmorillonite. It is a regularly interstratified clay mineral with alternate pairs of dioctahedral mica-like layers (nonexpansible) and dioctahedral montmorillonite-like layers (expansible) in a 1:1 ratio. Chitosan/organic rectorite (chitosan/OREC) nanocomposite films with different mass ratios of chitosan to organic rectorite and corresponding drug-loaded films were successfully obtained by a casting/solvent evaporation method. The structures of the films were evaluated by FTIR-ATR, XRD and SEM. A wide variety of material characteristics for the chitosan/OREC nanocomposite films were investigated, including the water resistance, mechanical property, optical transmittance, anti-ultraviolet capacity and bactericidal activity. The characteristics of the nanocomposite films were related to the amount and the interlayer distance of OREC in them. In vitro drug-controlled release studies showed a slower and more continuous release for the nanocomposite films in comparison with pure chitosan film, and the drug-delivery cumulative release was proportional to the amount and the interlayer distance of OREC. The chitosan/OREC nanocomposites films provide promising applications as antimicrobial agents, water-barrier compounds, anti-ultraviolet compounds, and drug-controlled release carriers in antimicrobial food packaging and drug-delivery system.
Co-reporter:Qun Wang, Zhanfeng Dong, Yumin Du, John F. Kennedy
Carbohydrate Polymers 2007 Volume 69(Issue 2) pp:336-343
Publication Date(Web):1 June 2007
DOI:10.1016/j.carbpol.2006.10.014
Films of chitosan and polyethylene glycol (PEG), with ciprofloxacin hydrochloride as model drug incorporated at different concentrations, have been obtained by a casting/solvent evaporation method. Interrelated chemical, morphological and mechanical characterizations included the component ratio of chitosan and PEG, the loaded amount of ciprofloxacin hydrochloride, the pH and ionic strength of the release solution, the thickness of the drug loaded films, the coating layer of sodium alginate and the cross-linking time with tripolyphosphate (TPP) and others. The results of controlled release tests showed that the amount of ciprofloxacin hydrochloride released increased with an increase in the proportion of PEG and decreased as the amount of drug loaded in the film increased; however, the cumulative release amount of the drug increased. The chitosan/PEG films were also sensitive to pH and ionic strength. In simulated intestinal fluid, the thickness of the film increased from 35 to 85 μm with a concomitant reduction of the ciprofloxacin hydrochloride concentration from 100% to 71%. Differing the concentration of sodium alginate coating solution reduced the release of ciprofloxacin hydrochloride by as much as 16% in simulated gastric fluid and 38% in simulated intestinal fluid. When the cross-linking time of these films in the TPP solution were 0, 5, 15 and 30 min, the drug release rate attained 100%, 100%, 70% and 42%, respectively, within 24 h.
Co-reporter:Yu-Feng Tang, Yu-Min Du, Xian-Wen Hu, Xiao-Wen Shi, John F. Kennedy
Carbohydrate Polymers 2007 Volume 67(Issue 4) pp:491-499
Publication Date(Web):19 February 2007
DOI:10.1016/j.carbpol.2006.06.015
Thermosensitive hydrogels that are triggered by changes in environmental temperature thus resulting in in situ hydrogel formation have recently attracted the attention of many investigators for biomedical applications. In the current work, the thermosensitive hydrogel was prepared through the mixture of chitosan (CS), poly(vinyl alcohol) (PVA) and sodium bicarbonate. The mixture was liquid aqueous solutions at low temperature (about 4 °C), but a gel under physiological conditions. The hydrogel was characterized by FTIR, swelling and rheological analysis. The effect of hydrogel composition and temperature on both the gel process and the gel strength was investigated from which possible hydrogel formation mechanisms were inferred. In addition, the hydrogel interior morphology as well as porosity of structure was evaluated by scanning electron microscopy (SEM). The potential of the hydrogels as vehicles for delivering bovine serum albumin (BSA) were also examined. In this study, the physically crosslinked chitosan/PVA gel was prepared under mild conditions without organic solvent, high temperature or harsh pH. The viscoelastic properties, as investigated rheologically, indicate that the gel had good mechanical strength. The gel formed implants in situ in response to temperature change, from low temperature (about 4 °C) to body temperature, which was very suitable for local and sustained delivery of proteins, cell encapsulation and tissue engineering.
Co-reporter:Ying Hu, Yumin Du, Jianhong Yang, John F. Kennedy, Xiaohui Wang, Liansheng Wang
Carbohydrate Polymers 2007 Volume 67(Issue 1) pp:66-72
Publication Date(Web):2 January 2007
DOI:10.1016/j.carbpol.2006.04.015
Guanidinylated chitosan derivatives with different molecular weights have been synthesized by the guanidinylation reaction of chitosan with aminoiminomethanesulfonic acid (AIMSOA); the structures of AIMSOA and guanidinylated chitosan were characterized by UV, FT-IR, fluorescence and 13C NMR. The absorbance at 230 nm, a emission band ranging from 500 to 540 nm in emission spectrum were observed. In addition, the strong peaks at 1649, 1555, 1380 cm−1, the distinct signals at 158.3 ppm in 13C NMR were found. The substitution degrees of guanidinylated chitosan were confirmed by elemental analysis. In vitro antibacterial activity of guanidinium derivatives was evaluated against Staphylococcus aureus, Bacillus subtilis, Escherichia coli and Pseudomonas aeruginosa. Compared with chitosan, guanidinylated chitosan had much better antibacterial activity, whose minimum inhibitory concentrations in aqueous hydrochloric acid (pH 5.4) were 4 times lower than those of chitosan. Interestingly, guanidinylated chitosan inhibited the growth of S. aureus and B. subtilis at pH 6.6. The antibacterial activity of guanidinylated chitosan enhanced with decreasing pH.
Co-reporter:Jin Li, Yumin Du, Hongbo Liang
Polymer Degradation and Stability 2007 Volume 92(Issue 3) pp:515-524
Publication Date(Web):March 2007
DOI:10.1016/j.polymdegradstab.2006.04.028
The degradative activities of neutral protease against chitosan samples with different molecular parameters were characterized. The effects of the degree of deacetylation (DD) and molecular weight (MW) of chitosan on its susceptibility to degradation were investigated. The DD and MW of the chitosans were determined using potentiometric titration and viscometry, respectively. The molecular weight distribution of initial and degraded commercial chitosan was investigated by gel permeation chromatography. Initial degradation rates (r) were determined from the plots of viscosity decrease against time of degradation. The time courses of degradation of chitosans with neutral protease were non-linear and the enzymatic hydrolysis was an endo-action. Classical Michaelis–Menten kinetic parameters were measured by analyzing the amount of reducing sugars and Eadie–Hofstee plots established that hydrolysis of chitosan by neutral protease obeyed Michaelis–Menten kinetics. Michaelis–Menten parameters and initial degradation rates were calculated and compared to determine the influences of DD and MW on hydrolysis. The results showed that higher DD and higher MW chitosans possessed a lower affinity for the enzyme and a slower degradation rate. Those samples with a lower DD and lower MW were more susceptible substrates.
Co-reporter:Tao Li;Xiao-Wen Shi;Yu-Min Du;Yu-Feng Tang
Journal of Biomedical Materials Research Part A 2007 Volume 83A(Issue 2) pp:383-390
Publication Date(Web):20 APR 2007
DOI:10.1002/jbm.a.31322
Quaternized chitosan (QCS)/alginate (AL) nanoparticles (QCS/AL) were successfully prepared in neutral condition for the oral delivery of protein. The physicochemical structure of the QCS/AL nanoparticles was characterized by IR spectroscopy and transmission electron microscopy. The diameter of the nanoparticles with a positive surface charge was about 200 nm. The load of bovine serum albumin (BSA) was affected by the concentration and the molecular parameters, i.e. degree of substitution (DS) and weight-average molecular weight (Mw) of QCS, as well as the concentration of BSA. The release of BSA from nanoparticles was pH-dependent. Quick release occurred in 0.1M phosphate buffer solution (PBS, pH = 7.4), while the release was slow in 0.1M HCl (pH = 1.2). The DS and Mw of QCS play important roles in the release of BSA in vitro. QCS with high Mw accelerated the release of BSA in acid, while high DS retarded the release of BSA in both 0.1M HCl and 0.1M PBS. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res 2007
Co-reporter:Na Zhang;Qun Wang;Xianwen Hu;Jianhong Yang
Journal of Biomedical Materials Research Part A 2007 Volume 82A(Issue 1) pp:122-128
Publication Date(Web):31 JAN 2007
DOI:10.1002/jbm.a.31075
Fibers of alginate and polyethylene glycol (PEG), with salicylic acid (SA) as model drug incorporated in different concentrations, were obtained by spinning their solution through a viscose-type spinneret into a coagulating bath containing aqueous CaCl2 and ethanol. Chemical, morphological, and mechanical properties characterization were carried out, as well as the studies of the factors that influence the drug releasing from alginate/PEG fibers. These factors included the component ratio of alginate and PEG, the loaded amount of SA, the pH, and the ionic strength of the release solution and others. The best values of the tensile strength at 13.41 cN/tex and breaking elongation at 23.13% of blend fibers were obtained when the PEG content was 5 wt %; the water swelling ratio (WSR) of blend fibers increased as the composition of PEG was raised. The results of controlled release tests showed that the amount of SA released increased with an increase in the proportion of PEG present in the fiber. Moreover, the release rate of drug decreased as the amount of drug loaded in the fiber increased, but the cumulative release amount is increasing. The alginate/PEG fibers were also sensitive to pH and ionic strength. For pH 7.4 the drug release was faster compared to pH 1.0, being simultaneously accelerated by a higher ionic strength. All the results indicated that the alginate/PEG fiber was potentially useful in drug delivery systems. © 2007 Wiley Periodicals, Inc. J Biomed Mater Res, 2007
Co-reporter:Yun-Yang Wan, Yu-Min Du, Lian-Sheng Wang, Kai Hu, Gong-Zhen Cheng, Jian-Hong Yang, F. John Kennedy
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2007 Volume 296(1–3) pp:270-276
Publication Date(Web):15 March 2007
DOI:10.1016/j.colsurfa.2006.10.009
A kind of nonionic surfactant didodecyl 2-(2,3,4,5,6-pentahydroxy-hexanamido) pentanedioate (DHAD) was synthesized by a green chemistry approach. Instead of use of hazardous and non reuseable catalysts, a highly efficient, easily prepared and environmentally friendly catalyst—SnCl4/C (C1) complex has been developed. This can be reused at least six times with no less than 90% yields without using solvents. The structure of DHAD was characterized by elemental analysis, Fourier transform infrared (FT-IR) spectroscopy, and 1H, and 13C nuclear magnetic resonance (NMR) spectroscopy and 1H–1H COSY.
Co-reporter:Tao Feng;Jin Li;Yuanan Wei
European Food Research and Technology 2007 Volume 225( Issue 1) pp:
Publication Date(Web):2007 May
DOI:10.1007/s00217-006-0391-0
Different molecular weight water-soluble chitosan (half N-acetylated chitosan) was prepared and the structure of water-soluble chitosan was characterized by FT-IR. The pH dependence of water solubility of water-soluble chitosan was evaluated from turbidity. Total antioxidant activity, reducing power, superoxide anion radical and hydroxyl radical quenching assay, metal chelating activity, and H2O2 scavenging activity were used for the evaluation of different molecular weight half N-acetylated chitosan in vitro. Low-molecular weight water-soluble chitosan (WSC4) exhibited high reductive capacity and expressed good inhibition of linoleic acid peroxidation in the linoleic acid model system. WSC4 (0.25 mg/mL) scavenged 78.8% of superoxide radical. At 5 mg/mL, scavenging percentage of WSC1, WSC2, WSC3, and WSC4 against hydroxyl radical was 49.3%, 66.8%, 77.1%, and 83.7%, respectively. These results indicate that water-soluble chitosan is an ideally natural antioxidant, and its antioxidant activity depends on its molecular weight.
Co-reporter:YunYang Wan;Rong Lu;Kazuhiro Akiyama
Science China Chemistry 2007 Volume 50( Issue 2) pp:179-182
Publication Date(Web):2007 April
DOI:10.1007/s11426-007-0022-z
A simple one step synthesis of pinoresinol and its derivatives-active components of Du-Zhong (Eucommia ulmoides)-from coniferyl alcohol and p-courmaryl alcohol with higher yields was achieved by Rhus laccases (RL) catalysis in water miscible organic solvents. Biomacromolecules dehydrogenative polymers (DHP) were only synthesized by fungal laccases, not by RL. The structures and the reaction mechanism were discussed to promote the understanding of the function of laccases in the process of lignin biosynthesis.
Co-reporter:Lihong Fan, Yumin Du, Baozhong Zhang, Jianhong Yang, Jinping Zhou, John F. Kennedy
Carbohydrate Polymers 2006 Volume 65(Issue 4) pp:447-452
Publication Date(Web):13 September 2006
DOI:10.1016/j.carbpol.2006.01.031
Alginate/carboxymethyl chitosan blend fibers, prepared by spinning their mixture solution through a viscose-type spinneret into a coagulating bath containing aqueous CaCl2, were studied for structure and properties with the aid of infrared spectroscopy (IR), X-ray diffraction (XRD) and scanning electron micrography (SEM). The analyses indicated a good miscibility between alginate and carboxymethyl chitosan, because of the strong interaction from the intermolecular hydrogen bonds. The best values of the dry tensile strength and breaking elongation were obtained when carboxymethyl chitosan content was 30 and 10 wt%, respectively. The wet tensile strength and breaking elongation decreased with the increase of carboxymethyl chitosan content. Introduction of CM-chitosan in the blend fiber improved water-retention properties of blend fiber compared to pure alginate fiber. Antibacterial fibers, obtained by treating the fibres with aqueous solution of N-(2-hydroxy)-propyl-3-trimethylammonium chitosan chloride and silver nitrate, respectively, exhibited good antibacterial activity to Staphylococcus aureus.
Co-reporter:Liping Sun, Yumin Du, Jianghong Yang, Xiaowen Shi, Jin Li, Xiaohui Wang, John F. Kennedy
Carbohydrate Polymers 2006 Volume 66(Issue 2) pp:168-175
Publication Date(Web):27 October 2006
DOI:10.1016/j.carbpol.2006.02.036
Chitin has been subjected to regiospecific oxidation at C-6 with NaOCl in the presence of 2,2,6,6-tetramethyl-1-piperidinyloxy (TEMPO) and NaBr at room temperature in aqueous solution to yield fully soluble 6-carboxychitin. Several physical and chemical pretreatments of the original chitin changed its crystal structure from α to β. After this pretreatment of the chitin the oxidation was easier to effect and the yield was greatly increased from 36% to 97% and the molecular weight was about 4 × 104 which was ca. 8 times that from the unpretreated chitin. Infrared spectroscopy (IR), X-ray diffraction, 13C NMR and solid-state NMR measurements, and thermal analysis techniques were used to characterize their molecular structures. The moisture absorption and retention abilities of these types of compounds were compared with those of sodium hyaluronan and carboxymethyl chitosan (CMCS) and were found to be superior. They therefore have the potential to substitute for hyaluronan for use in cosmetics and clinical medicine fields.
Co-reporter:Jun Cai, Jianhong Yang, Yumin Du, Lihong Fan, Yanlin Qiu, Jin Li, John F. Kennedy
Carbohydrate Polymers 2006 Volume 65(Issue 2) pp:211-217
Publication Date(Web):25 July 2006
DOI:10.1016/j.carbpol.2006.01.003
An extracellular chitin deacetylase from Scopulariopsis brevicaulis has been produced using chitin as sole carbon resource of culture medium. The enzyme activity was 10–11 units ml−1 culture supernatant after the strain was shaken at 200 rpm and 29 °C for 96 h. The enzyme was purified 74-fold at 38% yield through ammonium sulfate precipitation, and Sephadex G-25, and G-100 column chromatography. The apparent molecular weight of 55 kDa, as determined by SDS-PAGE and gel filtration chromatography, suggested that the enzyme exists as a single component. The enzyme was active on chitooligosaccharides with at least two N-acetyl-glucosamine residues, but the activity increased with the number of N-acetyl-glucosamine residues. When hexa-N-acetylchitohexaose was used as substrate, the optimum pH for enzyme activity was determined to be 7.5, and the optimum temperature was 55 °C. Under these conditions, the activity of enzyme was studied on water-soluble chitosan, chitin from Aspergillus niger and shrimp crystalline chitin. The structures of products were characterized by FT-IR, XRD and potentiometric titration. The results indicated that degree of substrate crystallinity had an important effect on enzyme activity. The enzyme had high deacetylating activity on amorphous chitin from A. niger mycelium (37% deacylation) and water-soluble chitosan (33%) but low. activity on shrimp crystalline chitin (3.7%).
Co-reporter:Jun Cai, Jianhong Yang, Yumin Du, Lihong Fan, Yanlin Qiu, Jin Li, John F. Kennedy
Carbohydrate Polymers 2006 Volume 64(Issue 2) pp:151-157
Publication Date(Web):11 May 2006
DOI:10.1016/j.carbpol.2005.11.004
A new route had been devised for obtain chitosan with stable properties and good quality suitable for medical, cosmetic and other purposes. Waste Aspergillus niger mycelia from a citric acid production plant were used as a source of chitosan. The extraction of chitosan was operated with lysozyme, snailase, neutral protease and novel chitin deacetylase from Scopulariopsis brevicaulis at the optimum condition of every enzyme. The optimum dosage of neutral protease and chitin deacetylase were 0.17 g (5100 units) per 100 g fresh mycelia and 1200 units per 100 g fresh mycelia, respectively. The deproteinization rate was 59.9%. The recovery rate of glucosamine was 50%. Weight-averaged molecular weight, degree of deacetylation of chitosan and the content of glucosamine were 267.97 kDa, 73.6 and 84.4%, respectively. Compared with chemical extraction methods, the weight-average molecular weight was three times higher whilst other parameters were very similar. The results of FT-IR, X-ray and elemental analysis proved that the structure of chitosan of enzymatic extraction was very similar to those of shrimp chitosan.
Co-reporter:Li-Ping Sun;Yu-Min Du;Xiao-Wen Shi;Xiao Chen;Jian-Hong Yang;Yong-Mei Xu
Journal of Applied Polymer Science 2006 Volume 102(Issue 2) pp:1303-1309
Publication Date(Web):28 JUL 2006
DOI:10.1002/app.23718
A new approach to prepare chemically modified carboxymethyl chitosan (CM) derivatives was reported, from which initially CM was prepared from chitosan, then N-quaternary ammonium group was introduced by the reaction of CM with 2,3-epoxypropyl trimethylammonium. The structures of the derivatives were characterized by FTIR, XRD, 13C-NMR, and gel permeation chromatography. The capability of moisture-absorption and moisture-retention was investigated. It was found that the moisture-absorption and moisture-retention ability of the new derivatives quaternized carboxymethyl chitosan (CMQ) are higher than not only that of CM but also that of chitosan quaternary (Q) and carboxymethyl group and quaternary ammonium group are in synergistic effect. Relationships between molecular structures (including degree of substitution of carboxymethylation group, degree of substitution of quaternary group, and molar mass) and functions of CMQ were also studied. The moisture absorption kinetics of CMQ was discussed and the diffusion of water molecules in it looks likely to be non-Fickian type. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1303–1309, 2006
Co-reporter:Jin Li;Hongbo Liang
Journal of Applied Polymer Science 2006 Volume 102(Issue 2) pp:1098-1105
Publication Date(Web):28 JUL 2006
DOI:10.1002/app.24306
Preparation of water-soluble chitosan (WSC) was made by treating partially N-deacetylated chitosan with acetic anhydride in aqueous acetic acid. The optimal conditions of preparing WSC were determined on the basis of orthogonal tests. Low molecular weight WSC with broad molecular weight (600–1.5 kDa) were obtained by the depolymerization of WSC using cellulase at optimum condition of pH 4.5 and 60°C. The solubility of WSC in water and aqueous organic solvents was investigated in detail. Weight–average molecular weight (Mw) and molecular weight distribution (Mw/Mn) of samples were measured by gel permeation chromatography. The structure of WSC and its degraded products were characterized by XRD, FTIR, and MALDI-TOF MS. The decrease of molecular weight led to transformation of crystal structure and the increase of solubility, but the chemical structures of residues were not modified compared to WSC, which was not hydrolyzed. The solubility of the WSC in water and aqueous organic solvents increased with the decrease of molecular weight. The solubility of the WSC with low molecular weight was rather high even in aqueous dimethylacetamide and dimethylsulfoxide. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 1098–1105, 2006
Co-reporter:Jin Li;Liping Sun;Hongbo Liang;Tao Feng;Yuan'an Wei;Pinjia Yao
Journal of Applied Polymer Science 2006 Volume 101(Issue 6) pp:3743-3750
Publication Date(Web):27 JUN 2006
DOI:10.1002/app.23398
Enzyme hydrolysis with immobilized neutral protease was carried out to produce low molecular weight chitosan (LMWC) and chito-oligomers. Neutral protease was immobilized on (CS), carboxymethyl chitosan (CMCS), and N-succinyl chitosan (NSCS) hydrogel beads. The properties of free and immobilized neutral proteases on chitosaneous hydrogel beads were investigated and compared. Immobilization enhanced enzyme stability against changes in pH and temperature. When the three different enzyme supports were compared, the neutral protease immobilized on CS hydrogel beads had the highest thermal stability and storage stability, and the enzyme immobilized on NSCS hydrogel beads had the highest activity compared to those immobilized on the other supports, despite its lower protein loading. Immobilized neutral protease on all the three supports had a higher Km (Michaelis-Menten constant) than free enzyme. The Vmax (maximum reaction velocity) value of neutral protease immobilized on CS hydrogel beads was lower than the free enzyme, whereas the Vmax values of enzyme immobilized on CMCS and NSCS hydrogel beads were higher than that of the free enzyme. Immobilized neutral protease on CS, CMCS, and NSCS hydrogel beads retained 70.4, 78.2, and 82.5% of its initial activity after 10 batch hydrolytic cycles. The activation energy decreased for the immobilization of neutral protease on chitosaneous hydrogel beads. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 3743–3750, 2006
Co-reporter:Jin Li;Yuan An Wei;Ping Jia Yao;Yu Min Du;Hong Bo Liang
Journal of Applied Polymer Science 2006 Volume 102(Issue 5) pp:4185-4193
Publication Date(Web):28 SEP 2006
DOI:10.1002/app.24555
Neutral protease was immobilized on glutaraldehyde-pretreated N-succinyl chitosan hydrogel beads and the biocatalyst obtained was used for the preparation of low molecular weight chitosan and chito-oligomers with molecular weight of 1.9–23.5 kDa from commercial chitosan. Factors affecting the chitinolytic hydrolysis were described. The degradation was monitored by gel permeation chromatography. The structure of degraded chitosan was characterized by Fourier transform infrared, X-ray diffraction and liquid chromatography-mass spectrometry. Immobilized neutral protease showed optimal depolymerization at pH 5.7 and 50°C. The degree of deacetylation of the hydrolysates did not change compared to that of the initial chitosan. The decrease of molecular weight led to transformation of crystal structure but the chemical structures of residues were not modified. The degree of polymerization of chito-oligomers was mainly from 3 to 8. The method allows cyclic procedures of immobilized enzyme and N-succinyl chitosan support utilization, and is suitable for a large-scale production of the low molecular weight chitosan and chito-oligomers free of protein admixtures. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102:4185–4193, 2006
Co-reporter:Xiaowen Shi;Abo Dou;Baozhong Zhang;Liping Sun;Xiaowen Shi;Liping Sun;Baozhong Zhang;Abo Dou
Journal of Applied Polymer Science 2006 Volume 100(Issue 6) pp:4614-4622
Publication Date(Web):29 MAR 2006
DOI:10.1002/app.23021
Polyelectrolyte complex (PEC) beads were prepared from water-soluble chitosan (WSC) and alginate complex solution with different ratios by dropping method, and all procedures used were performed in aqueous medium at neutral environment. The structure and morphology of the beads were characterized by IR spectroscopy and scanning electron microscopy (SEM). IR spectroscopy confirmed the electrostatic interactions between amino groups of WSC and carboxyl groups of alginate. SEM showed internal section of the PEC bead, which had porous structure compared with compact structure of alginate beads. The swelling behavior, encapsulation efficiency, and release behavior of bovine serum albumin (BSA) from the beads at different pHs were investigated. PEC beads demonstrated different responses to pH from alginate beads. The ratio of WSC to alginate influenced the encapsulation and release of BSA. At pH 1.2, small amount (< 15%) of BSA was released from the PEC beads except AC12. However, at pH 7.4, a large amount (> 80%) of BSA was released from AL in the first 3 h due to the rapid disintegration of the beads, whereas BSA release was retarded from complex beads due to the forming of PEC. The results suggested that the WSC/alginate beads could be a suitable polymeric carrier for site-specific protein drug delivery in the intestine. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4614–4622, 2006
Co-reporter:Qun Wang;Xianwen Hu;Jianhong Yang;Lihong Fan;Tao Feng
Journal of Applied Polymer Science 2006 Volume 101(Issue 1) pp:425-431
Publication Date(Web):25 APR 2006
DOI:10.1002/app.22369
Alginate and soy protein isolate blend fibers were prepared by spinning their solution through a viscose-type spinneret into a novel coagulating bath containing aqueous CaCl2, HCl, and ethanol. The structures and properties of the fibers were studied with the aids of infrared spectra (IR), X-ray diffraction (XRD), and scanning electron micrograph (SEM). Mechanical properties and water-retention properties were measured. And with the sample of AS1 fiber (soy protein isolate weight content was 10%), the effects of the composition of the novel coagulating bath were also studied. The best values of the tensile strength of AS1 were 14.1 cN/tex in the dry state and 3.46 cN/tex in the wet state, respectively. Both the dry state and wet state breaking elongation were also having the best value 20.71% and 56.7% with AS1. Mechanical properties of the AS1 enhanced with the CaCl2 content increased in the coagulating bath. When the HCl content was 1%, the mechanical property of the fiber was best. Ethanol in the coagulating bath increased the wet mechanical properties of the fiber by 41.2% (tensile strength) and 45.1% (breaking elongation) when the ethanol weight content in the coagulating bath was 50%; but it had little effect on the dry mechanical properties. And the water-retention value (WRV) of blend fibers decreased as the amount of soy protein isolate was raised. The structure analysis indicated that there were strong interaction and a certain level of miscibility between alginate and soy protein isolate. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 425–431, 2006
Co-reporter:Wen He;Wenbing Dai;Yan Wu;Mian Zhang
Journal of Applied Polymer Science 2006 Volume 99(Issue 3) pp:1140-1146
Publication Date(Web):18 NOV 2005
DOI:10.1002/app.22317
N-trimethyl chitosan chloride (TMC), with degree of quaternization (DQ) of 42.77% (TMC40) and 63.03% (TMC60), respectively, were synthesized and used as absorption enhancers in an insulin rectal liquid suppository from poloxamers. The effects of the TMCs on the liquid suppository were investigated. Compared with sodium salicylate (10%), which increased the gelation temperature and decreased the gel strength and bioadhensive force of the liquid suppository, both TMCs increased the three indices due to hydrogen bonding between the amino groups of TMCs and hydroxyl groups of poloxamers. The higher the concentration of TMCs was, the higher the three indices were. At the same concentration, the enhancing effect of TMC60 was higher than that of TMC40. Compared with those of 10% sodium salicylate, the enhancing effects of TMC40 with concentrations of 0.05% and 0.10% and TMC60 with concentration of 0.05% were weaker, while the other testing concentrations all showed better absorption enhancing ability with lower plasma glucose levels, AUC0–4 h (the area below basal glucose level) and Cnadir (the plasma glucose levels at the nadir). Histological assessment was performed by observing irritation of the liquid suppository on the rectal tissues and observation rate of three types of gland changes in the rectal epithelium. Compared with the control (75.48 ± 16.76), TMC40 and TMC60 exhibited little change in observation rates of normal gland (72.10 ± 10.24 and 71.93 ± 9.88, respectively), while sodium salicylate showed significant lower observation rates of normal gland (51.28 ± 13.44). The insulin rectal liquid suppository with TMCs is more effective and safer than that with sodium salicylate. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 99: 1140–1146, 2006
Co-reporter:Tao Feng;Jianhong Yang;Jin Li;Xiaowen Shi
Journal of Applied Polymer Science 2006 Volume 101(Issue 3) pp:1334-1339
Publication Date(Web):17 APR 2006
DOI:10.1002/app.22959
A nonspecific chitosan hydrolytic enzyme, cellulase, was immobilized onto magnetic chitosan microspheres, which was prepared in a well spherical shape by the suspension crosslinking technique. The morphology characterization of the microspheres was carried out with scanning electron microscope and the homogeneity of the magnetic materials (Fe3O4) in the microspheres was determined from optical micrograph. Factors affecting the immobilization, and the properties and stabilities of the immobilized enzyme were studied. The optimum concentration of the crosslinker and cellulase solution for the immobilization was 4% (v/v) and 6 mg/mL, respectively. The immobilized enzyme had a broader pH range of high activity and the loss of the activity of immobilized cellulase was lower than that of the free cellulase at high temperatures. This immobilized cellulase has higher apparent Michaelis–Menten constant Km (1.28 mg/mL) than that of free cellulase (0.78 mg/mL), and the maximum apparent initial catalytic rate Vmax of immobilized cellulase (0.39 mg mL−1 h−1) was lower than free enzyme (0.48 mg mL−1 h−1). Storage stability was enhanced after immobilization. The residual activity of the immobilized enzyme was 78% of original after 10 batch hydrolytic cycles, and the morphology of carrier was not changed. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 1334–1339, 2006
Co-reporter:Xiaowen Shi;Jianhong Yang;Baozhong Zhang;Liping Sun;Xiaowen Shi;Jianhong Yang;Baozhong Zhang;Liping Sun
Journal of Applied Polymer Science 2006 Volume 100(Issue 6) pp:4689-4696
Publication Date(Web):29 MAR 2006
DOI:10.1002/app.23040
The aim of this study was to evaluate the potential of carboxymethyl chitosan (CM-chitosan) nanoparticles as carriers for the anticancer drug, doxorubicin (DOX). Different kinds of CM-chitosan with various molecular weight (MW) and degree of substitution (DS) were employed to prepare nanoparticles through ionical gelification with calcium ions. Factors affecting nanoparticles formation in relation to MW and DS of CM-chitosan were discussed. By the way of dynamic light scattering (DLS), TEM, and atomic force microscopy (AFM), nanoparticles were shown to be around 200–300 nm and in a narrow distribution. FTIR revealed strong electrostatic interactions between carboxyl groups of CM-chitosan and calcium ions. DOX delivery was affected by the molecular structure of CM-chitosan. Increasing MWs of CM-chitosan from 4.50 to 38.9 kDa, DOX entrapment efficiency was enhanced from 10 to 40% and higher DS slightly improved the load of DOX. In vitro release studies showed an initial burst followed by an extended slow release. The DOX release rate was hindered by CM-chitosan with high MW and DS. These preliminary studies showed the feasibility of CM-chitosan nanoparticles to entrap DOX and the potential to deliver it as controlled release nanoparticles. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 4689–4696, 2006
Co-reporter:Wen He;Lihong Fan
Journal of Applied Polymer Science 2006 Volume 100(Issue 3) pp:1932-1939
Publication Date(Web):2 FEB 2006
DOI:10.1002/app.22949
The aim of this study was to optimize the formula of free blended coating membrane of ethyl cellulose (EC) and chitosan (CS), including their suitable ratio range and the best plasticizer used. The dry films were produced by a casting/solvent evaporation method, with different volume ratio of EC and CS solution plasticized by various plasticizers, respectively. The wet films were prepared by immersing dry films in pH 6.8 phosphate buffer saline (PBS) for 24 h. The promising ratio range of EC/CS was below 20/5 or 20/6 with various plasticizer, which was determined by comparing the viscosity of the blended solutions and the morphology of the blended films. The efficiency of plasticization was evaluated by measuring glass transition temperature (Tg). All the testing plasticizers have good compatibility with EC or CS and dibutyl phthalate (DBP) have the strongest efficiency inducing the lowest Tg (39.9°C) of the film. Mechanical properties were evaluated by the ratio of tensile strength (T) to elastic modulus (E). In the wet state, the films with DBP had the highest T/E value (1.2). The results of leaching of plasticizers also verified that DBP was the most stable plasticizer in the films. The release rates of tetramethylpyrazine phosphate (TMPP) through the pellets coated with the blended films of EC/CS (20 : 6 v/v) plasticized by various plasticizers showed that the more water-soluble the plasticizer was, the more quickly TMPP dissolved from the coated pellets, which further indicated that the water-insoluble plasticizers (such as DBP) could be more applicable to keep the sustained or controlled release property of the blended films in wet state. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 1932–1939, 2006
Co-reporter:Jianhong Yang, Yumin Du, Ronghua Huang, Liping Sun, Hui Liu, Xiaohai Gao, John F. Kennedy
Carbohydrate Polymers 2005 Volume 59(Issue 1) pp:101-107
Publication Date(Web):3 January 2005
DOI:10.1016/j.carbpol.2004.09.004
Lacquer polysaccharide from Rhus vernicifera was separated into two fractions with high and low molecular weights, LPH and LPL. LPL was degraded using dilute sulphuric acid. Besides molecular weight, products had only a little change in their contents of α-l-rhamnopyranose, α-l-arabinofuranose and α-d-galactopyranose. The side chains of LPH and LPL were partially removed with NaIO4 oxidation. The structures of all polysaccharides were investigated by GPC, FT-IR, 1H and 13C NMR spectroscopy. S-180 ascites tumour in mice was used to assay the antitumour activity of lacquer polysaccharide and its derivatives using two doses (150 and 300 mg/kg/d). The antitumour activity was related to Mw and the branching structure of polysaccharide. Natural polysaccharides had significant activity, and LPL had the highest activity, its inhibitory rate by intraperitoneal injection for 7 d using a 150 mg/kg/d dose reached 63.5%. Decrease of Mw and removal of side chains led to reduction or loss of antitumour activity. Experimental results also showed that the low dose group had higher activity, and the bloody ascites was prevented by the polysaccharide groups.
Co-reporter:Xiao-Wen Shi;Yu-Min Du;Xue-Li Su;Jian-Hong Yang;Li-Ping Sun;Xiao-Hui Wang
Macromolecular Bioscience 2005 Volume 5(Issue 9) pp:881-889
Publication Date(Web):30 AUG 2005
DOI:10.1002/mabi.200500063
Summary: Complex beads composed of alginate and carboxymethyl chitin (CMCT) were prepared by dropping aqueous alginate-CMCT into an iron(III) solution. The structure and morphology of the beads were characterized by IR spectroscopy and scanning electron microscopy (SEM). IR confirmed electrostatic interactions between iron(III) and the carboxyl groups of alginate as well as CMCT, and the binding model was suggested as a three-dimensional structure. SEM revealed that CMCT had a porous morphology while alginate and their complex beads had a core-layer structure. The swelling behavior, encapsulation efficiency, and release behavior of bovine serum albumin (BSA) from the beads at different pHs were investigated. The BSA encapsulation efficiency was fairly high (>90%). It was found that CMCT disintegrated at pH 1.2 and alginate eroded at pH 7.4 while the complex beads could effectively retain BSA in acid (>85%) and reduce the BSA release at pH 7.4. The results suggested that the iron(III)-alginate-CMCT bead could be a suitable polymeric carrier for site-specific protein drug delivery in the intestine.
Co-reporter:Jin Li, Yumin Du, Jianhong Yang, Tao Feng, Aihua Li, Ping Chen
Polymer Degradation and Stability 2005 Volume 87(Issue 3) pp:441-448
Publication Date(Web):March 2005
DOI:10.1016/j.polymdegradstab.2004.09.008
Chitosan with 91.7% deacetylation was hydrolysed by a commercially available and efficient neutral protease. The degradation was monitored by gel permeation chromatography. Factors affecting the enzymatic hydrolysis of chitosan were studied. The structures of degraded chitosans were characterised by X-ray diffraction, Fourier transform infrared and MALDI-TOF mass spectrometry. Classical Michaelis–Menten kinetics parameters were measured by analysis of reducing sugars. The neutral protease showed optimum depolymerisation at pH 5.4 and 50 °C. Different reaction times gave chitosan with different molecular weights. Mn2+ was the most efficient activator of the enzymatic reaction. The enzymatic hydrolysis was endo-action and mainly occurred in a random fashion. The degree of deacetylation of the main hydrolysis products decreased compared with the initial chitosan. The decrease of molecular weight led to transformation of crystal structure and the increase of water solubility, but the chemical structures of residues were not modified. The degree of polymerisation of chito-oligomers was mainly from 3 to 8.
Co-reporter:Yu-min Du;Qun Wang;Li-hong Fan
Journal of Applied Polymer Science 2005 Volume 96(Issue 3) pp:808-813
Publication Date(Web):24 FEB 2005
DOI:10.1002/app.21518
With bovine serum albumin (BSA) as a model drug, drug-loaded films of chitosan (CS) and poly(vinyl alcohol) (PVA) were obtained by a casting/solvent evaporation method and crosslinked by tripolyphosphate (TPP). The films were characterized by FTIR, XRD, and SEM. The influential factors of drug-loaded films on drug-controlled release were studied. These factors included, primarily, the component ratio of CS and PVA, the loaded amount of BSA, the pH and ionic strength of the release solution, and the crosslinking time with TPP. The results showed that within 25 h, when the weight ratios of CS to PVA in the drug-loaded films were 90 : 10, 70 : 30, 50 : 50, and 30 : 50, the cumulative release rates of BSA were 63.3, 72.9, 81.8, and 91.8%, respectively; when the amounts of model drug were 0.1, 0.2, and 0.3 g, the release rates were 100, 81.8, and 59.6%, respectively; when the pH values of the drug release medium were 1.0, 3.8, 5.4, and 7.4, the release rates reached 100, 100, 37.9, and 7.8%, respectively; the cumulative release rates of BSA were 78.4, 82.3, 84.3, and 91.7% when the ionic strengths of the release solution were, respectively, 0.1, 0.2, 0.3, and 0.4M; when the crosslinking times of these drug films in the TPP solution were 0, 5, 15, 30, and 60 min, the release rates attained 100, 100, 81.8, 65, and 43.3%, respectively. All the results indicated that the CS/PVA film was useful in drug delivery systems. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 808–813, 2005
Co-reporter:Lihong Fan;Ronghua Huang;Qun Wang;Xiaohui Wang;Lina Zhang
Journal of Applied Polymer Science 2005 Volume 96(Issue 5) pp:1625-1629
Publication Date(Web):23 MAR 2005
DOI:10.1002/app.21610
Alginate and gelatin blend fibers were prepared by spinning their solution through a viscose-type spinneret into a coagulating bath containing aqueous CaCl2 and ethanol. The structure and properties of the blend fibers were studied with the aid of infrared spectra, scanning electron micrography, X-ray diffraction, and thermogravimetric analysis. Mechanical properties and water-retention properties were measured. The best values of the tensile strength and breaking elongation of blend fibers were obtained when gelatin content was 30 wt %. The water-retention values of blend fibers increase as the amount of gelatin is raised. The structural analysis indicated that there was strong interaction and good miscibility between alginate and gelatin molecules resulted from intermolecular hydrogen bonds. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 1625–1629, 2005
Co-reporter:Lingyun Chen;Zhigang Tian;Liping Sun
Journal of Polymer Science Part B: Polymer Physics 2005 Volume 43(Issue 3) pp:296-305
Publication Date(Web):13 DEC 2004
DOI:10.1002/polb.20212
The aggregation behavior of carboxymethyl chitosan (CM-chitosan) with various degrees of deacetylation (DD) and substitution (DS) was characterized with viscometry, gel permeation chromatography (GPC), and GPC coupled with laser light scattering (GPC-LLS). The results indicate that CM-chitosan has a strong tendency to form aggregates in aqueous solution and the aggregation behavior depends on DD and DS values. The apparent aggregation number (Nap), the gyration radius (Rg), and the weight fraction of the aggregates (Fa) reached maximum at a DD value of 50%, then decreased, with the DD value deviating from 50%. A higher DS value helped to form aggregates; when the DS value increased from 0.65 to above 1.0, Nap and Rg increased sharply. The dependence of the refractive index increment (dn/dc) on the DD and DS values was related to variation of the charge density and the hydrophobic interaction along the molecular chains. The conformations of CM-chitosan aggregates were studied by the LLS method. The aggregates showed a spherical shape, and the chain stiffness increased with introduction of the acetyl groups. The DS value had no clear influence on the chain conformation that was observed. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 43: 296–305, 2005
Co-reporter:Houbin Li, Yumin Du, Yongmei Xu, Huaiyu Zhan, John F. Kennedy
Carbohydrate Polymers 2004 Volume 58(Issue 2) pp:205-214
Publication Date(Web):19 November 2004
DOI:10.1016/j.carbpol.2004.06.044
N-(2-hydroxy-3-trimethylammonio)-propyl chitosan chloride, carboxymethyl chitosan and cationic starch were tested as wet-end additives for peroxide bleached reed kraft pulp. The adsorption of these polysaccharide samples and their interactions with the main components of pulp suspensions (cellulosic fiber, fines, dissolved and colloidal carbohydrates) were investigated by spectrophotometric, microelectrophoresis, particle size and retention/drainage methods. The results showed that the adsorption and aggregation behaviors which occur in pulp suspension were not only affected by the surface physicochemical characteristics of the cellulosic substrates but were also strongly affected by the nature (charge density, charge type and molar mass) of the polysaccharide additives. That is, N-(2-hydroxy-3-trimethylammonio)-propyl chitosan chloride additives were almost completely adsorbed onto the surfaces of the cellulosic fibers and aggregated the fines at low dosages, corresponding to those used in industrial operation. The optimum polymer concentration was increased with the reducing of the charge density of the quaternary chitosan additives. The adsorption of cationic starch onto the surfaces of cellulosic substrates was weaker than quaternary chitosan and showed higher optimum polymer concentration. The adsorption of carboxymethyl chitosan promoted the stabilization of the fines and colloidal carbohydrates rather than their aggregation. The polyelectrolyte complexes between hemicelluloses and the quaternary chitosans were formed in the adsorption processing, and these complexes then became adsorbed or deposited onto the cellulosic fibers, and this also correlates to the maximum fines retention and drainage. The experimental results also suggested that the dominant interaction between quaternary chitosan additives and cellulosic substrates are of an electrostatic nature and the fine flocculation was a charge patch mechanism.
Co-reporter:Hui Liu, Yumin Du, Xiaohui Wang, Ying Hu, John F Kennedy
Carbohydrate Polymers 2004 Volume 56(Issue 2) pp:243-250
Publication Date(Web):4 June 2004
DOI:10.1016/j.carbpol.2004.03.001
The interactions between chitosan and nonionic surfactant–alkyl β-d-glucopyranoside (AG) in solid state and aqueous solution have been investigated by using FT-IR spectroscopy, thermal analysis, powder X-ray diffraction, viscometry and gel permeation chromatography (GPC). The FT-IR spectra demonstrated that interaction between –NH3+ and –OH groups of chitosan and –OH groups of AG occurred by electrostatic force or hydrogen bonding. Results of thermal analysis and X-ray diffraction indicated that higher orders of structure such as aggregation chain conformation etc and crystallinity of chitosan seemed changed by addition of AG. Results of viscometry and GPC showed that, in aqueous solution, AG most likely made the chitosan chains extend and disaggregate. Interestingly, antimicrobial activity of the dynamic association (mixed solution of chitosan and AG) was much higher than that of chitosan and AG separately. Minimum inhibition concentration (MIC) of dynamic association was 2–8 times lower than that of chitosan alone, and it could kill more microorganisms in a shorter time. The reasons for the enhanced antimicrobial activity of the dynamic association mixture are carefully discussed in terms of the interaction between chitosan and AG.
Co-reporter:Houbin Li;Yongmei Xu
Journal of Applied Polymer Science 2004 Volume 91(Issue 4) pp:2642-2648
Publication Date(Web):22 DEC 2003
DOI:10.1002/app.13444
The adsorption of several chitosan samples with different degrees of deacetylation (65, 73, 85, and 92%) and their interactions with the main components of reed pulp suspensions were investigated with gel permeation chromatography, phenol/sulfuric acid spectrophotometry, microelctrophoresis, and retention/drainage methods. The results showed that the chitosan additive was almost completely adsorbed onto the surfaces of the cellulosic fibers, especially onto the surfaces of fines in a variety of cellulosic systems at low dosages corresponding to those used in industrial operations. This adsorption increased as the degree of deacetylation of chitosan increased. Moreover, the aggregation of the fine cellulosic particles was maximum at a dosage of about 10 mg/kg of chitosan. The uptake of dissolved and colloidal carbohydrates always occurred in the cellulose suspensions upon the addition of chitosan. These phenomena were related to the maximum retention of fines and drainage performance of the pulp suspensions; the optimum drainage dosage was found to be about 5–8 mg of chitosan per gram of oven-dried pulp. The interactions between chitosan and the cellulosic substrates were dominated by a bridging mechanism at pH ≈ 7 for these experiments. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 2642–2648, 2004
Co-reporter:Houbin Li, Yumin Du, Xiaojun Wu, Huaiyu Zhan
Colloids and Surfaces A: Physicochemical and Engineering Aspects 2004 Volume 242(1–3) pp:1-8
Publication Date(Web):2 August 2004
DOI:10.1016/j.colsurfa.2004.04.051
N-(2-Hydroxyl-3-trimethylammonio)-propyl chitosan chloride with varying degree of substitution (DS) and molecular weight (MW) were prepared using nucleophilic substitution reaction, the structure of the modified chitosan was discussed using IR, NMR and NMR spectroscopies. The results show that substitution reaction occurred at primary aliphatic amino group rather than hydroxyl group on chitosan under the reaction conditions. DS was influenced by the ratio of epoxide ring to chitosan. The retention-aid properties of quaternary chitosan for natural occurring CaCO3 fillers had been studied using adsorption and flocculation experiments. It was found that quaternary chitosan was almost completely adsorbed onto the surfaces of CaCO3 particles at the experimental dosage level. When DS of chitosan were same (93%), the complete surface coverage, which were determined by zeta potential measurements, of CaCO3 particles used in this work were 0.735 mg g−1, 0.826 mg l−1 and 0.953 mg g−1 for the quaternary salt with MW = 4.8 × 104, 11 × 104 and 19 × 104, respectively. The electrostatic attractive was expected to be the dominant driving forces for the adsorption. Compared with a commercial cationic starch, quaternary chitosan had a lower flocculation concentration and a higher flocculation performance. Further, the optimum flocculation concentration was decreased with the increasing DS, and the flocculation of CaCO3 dispersion was significantly affected by the molecular weight of quaternary chitosan. The optimum flocculation concentrations were about 4, 5 and 6 mg l−1 for the quaternary chitosan with MW = 19 × 104, 11 × 104 and 4.8 × 104, respectively. It was also shown that the CaCO3 flocculation induced by the adsorption of quaternary chitosan was dominated by a charge patch mechanism.
Co-reporter:Jianhong Yang, Yumin Du, Yan Wen, Tianyu Li, Ling Hu
Carbohydrate Polymers 2003 Volume 52(Issue 4) pp:397-403
Publication Date(Web):1 June 2003
DOI:10.1016/S0144-8617(02)00330-2
A branched ionic polysaccharide isolated from the sap of the Chinese lac tree (Rhus vernicifera) was chemically modified by sulfation using sulfur trioxide–pyridine (SO3·Py) complex as a reagent. Effects of molar ratio of SO3·Py complex to sugar unit, reaction time and reaction temperature on degree of sulfation (DS) and molecular weights of products were studied. Solvent was another important factor affecting sulfation reaction. In different solvents, when the other conditions remained constant, DS and molecular weights were in the following order: DMSO>DMF>FA (formamide) and DMSO
Co-reporter:Caiqin Qin;Zuqun Zhang;Yi Liu;Ling Xiao;Xiaowen Shi
Journal of Applied Polymer Science 2003 Volume 90(Issue 2) pp:505-510
Publication Date(Web):6 AUG 2003
DOI:10.1002/app.12687
An inverse emulsion method was used to prepare the chitosan microspheres, which were crosslinked with epichlorohydrin between the hydroxyl groups under protection of amino groups to obtain crosslinked chitosan resin. Further chemical modification with glycidyl trimethylammonium chloride was used to form the quaternary ammonium ion resin. The resin had different adsorption ability for the chromium (VI) in anionic forms from that of the crosslinked chitosan beads. The crosslinked chitosan resin exhibited maximum adsorption for chromium (VI) at pH 3.0 and the adsorption capacity decreased sharply above pH 6, whereas the adsorption capacities of quaternized chitosan resin were significant over pH 3 to 11. The quaternized resin was more efficient than the crosslinked chitosan resin in media of pH above 5. The complete removal of chromium from the solution of K2Cr2O7 was achieved with a column method using the quaternized chitosan resin, which was hard, and the decrease in pressure in the column was small. The breakthrough point of 10.0 mg L−1 chromium in quaternized resin column was 3200 mL g−1 resin greater than 600 mL g−1 resin in the crosslinked chitosan resin column. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 505–510, 2003
Co-reporter:Zhan Li, Yumin Du
Materials Letters 2003 Volume 57(16–17) pp:2480-2484
Publication Date(Web):May 2003
DOI:10.1016/S0167-577X(02)01297-1
The carboxymethyl derivative of chitosan, the structural polysaccharide of ascospore wall of Saccharomyces cerevisiae, was used to synthesize CdS nanoparticles (NPs) with an average size of about 4–5 nm and narrow size-distribution in a biomimic rout. The as-prepared CdS nanoparticles were characterized by transmission electron microscopy (TEM) and X-ray diffraction (XRD) and the interaction between CdS NPs and carboxymethyl chitosan (CMCH) was examined by FT-IR; due to this interaction, the resulting CdS colloid exhibit improved stability and enhanced luminescence in aqueous solution.
Co-reporter:Rupei Tang;Lihong Fan
Journal of Polymer Science Part B: Polymer Physics 2003 Volume 41(Issue 9) pp:993-997
Publication Date(Web):20 MAR 2003
DOI:10.1002/polb.10405
For improved mechanical and water-swelling properties of chitosan films, a series of transparent films were prepared with dialdehyde starch as a crosslinking agent. Fourier transform infrared and X-ray analysis results demonstrated that the formation of Schiff's base disturbed the crystallization of chitosan. The mechanical properties and water-swelling properties of the films were significantly improved. The best values of the tensile strength and breaking elongation were 113.1 MPa and 27.0%, respectively, when the dialdehyde starch content was 5%. All the crosslinked films still retained obvious antimicrobial effects toward S. aureus and E. coli, and they showed potential for biomedical applications. © 2003 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 41: 993–997, 2003
Co-reporter:C.Q. Qin, Y.M. Du, L. Xiao
Polymer Degradation and Stability 2002 Volume 76(Issue 2) pp:211-218
Publication Date(Web):2002
DOI:10.1016/S0141-3910(02)00016-2
The degradation of chitosan by hydrogen peroxide was studied. The degradation was monitored by gel permeation chromatography (GPC). The molecular weight distribution of partially degraded products from homogeneous reaction displayed a single-modal curve whereas that from heterogeneous reaction was bimodal. The molecular weight (Mw) decreased as the temperature, the time and/or hydrogen peroxide concentration increased. The dissolution of chitosan (pH 5.5) in minimum hydrochloride enhanced its degradation, but excessive hydrogen ion potentially inhibited the degradation. The formation of carboxyl group and deamination in the products indicated that the decrease of Mw was accompanied by structure changes. The degraded chitosans in Mw range from 51×103 to 1.2×103 were characterized by elemental analysis, X-ray diffraction, thermogravimetric analysis (TGA) and differential thermal analysis (DTA), Fourier transform infrared (FT–IR), carbon-13 nuclear magnetic resonance spectroscopy (13C-NMR). There was no significant chemical change in the backbone of chitosan with Mw of 51×103. But degraded chitosan with Mw of 3.5×103 had 1.71 mmol/g carboxyl groups and lost about 15% of amino groups. Further degradation led to more ring-opening oxidation of degraded products, the formation of carboxyl groups and faster deamination. The degraded chitosan with Mw of 1.2×103 had 2.86 mmol/g carboxyl groups and lost more than 40% of amino groups.
Co-reporter:Lingyun Chen;Huiqing Wu;Ling Xiao
Journal of Applied Polymer Science 2002 Volume 83(Issue 6) pp:1233-1241
Publication Date(Web):4 DEC 2001
DOI:10.1002/app.2290
Carboxymethyl chitins and chitosans (CM-chitins, CM-chitosans) of different substitution sites were prepared under different reaction conditions, and partially depolymerized carboxymethyl chitins of various molecular weights from 24.8 × 104 to 0.26 × 104 were obtained by degrading with chemical reagents. Degree of substitution (DS) was estimated by potentiometric titration. Substitution site was confirmed by infrared and 13C-NMR spectra. Molecular weights were determined with gel permeation chromatography and gel permeation chromatography combined with laser light scattering (GPC-LLS). Moisture-absorption and retention abilities of these compounds were tested in comparison with those of hyaluronic acid (HA). The results reveal that 6-carboxymethyl group in the molecular structure of chitin and chitosan is a main active site responsible for moisture retention. Although carboxymethylation at OH-3 and N position is not essential, they contribute to the ability. Moisture-retention ability is also related to molecular weight; that is, higher molecular weight helps to improve moisture-retention ability. 6-O-CM-chitin (chitosan) with a DS above 0.8 and molecular weight higher than 24.8 × 104 has the potential to substitute for HA for use in cosmetics and clinical medicine. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 83: 1233–1241, 2002
Co-reporter:Lingyun Chen
Journal of Applied Polymer Science 2002 Volume 86(Issue 8) pp:1838-1843
Publication Date(Web):10 SEP 2002
DOI:10.1002/app.11093
The aggregation behavior of 3,6-O-carboxymethylated chitin (3,6-O-CM-chitin) in aqueous solutions was investigated by viscometry, gel permeation chromatography (GPC), and GPC combined with laser light scattering (GPC-LLS) techniques. 3,6-O-CM-chitin has a strong tendency to form aggregates in NaCl aqueous solutions with the apparent aggregation number (Nap) of about 27. There were three kinds of aggregates corresponding to different cohesive energies, the aggregates with low cohesive energy were first dissociated at 60°C, the aggregates with middle cohesive energy were then dissociated at 80 to 90°C, and the aggregates with high cohesive energy were difficult to be disrupted by heating. Decreasing polysaccharide concentration (cp) or increasing NaCl concentration (cs) reduced the content of the aggregates. At the critical cp of 2.5 × 10−5 g/mL, the aggregates were dissociated into single chains completely. The change of aggregation and disaggregation of 3,6-O-CM-chitin in water–cadoxen mixtures occurred from 0.1 to 0.4 of vcad, and were irreversible. Intermolecular hydrogen bonding can be ascribed as main driving force for aggregation. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1838–1843, 2002
Co-reporter:Caiqin Qin;Ling Xiao;Yi Liu;Huaguang Yu
Journal of Applied Polymer Science 2002 Volume 86(Issue 7) pp:1724-1730
Publication Date(Web):5 SEP 2002
DOI:10.1002/app.11080
A series of chitosans with various molecular weights from 1.2 × 103 to 30.0 × 104 were prepared by oxidative degradation with H2O2 and characterized by IR, 13C-NMR, and gel permeation chromatography. Their carboxylic contents increased with a decrease in molecular weight (Mw). The moisture-absorption and moisture-retention capacities of resulting chitosans were dependent on both the molecular weight and the degree of deacetylation (DD). Microcalorimetry was first used to study the kinetics of action of the chitosans on a strain of Staphylococcus aureus at pH 7. The antibacterial activity of the water-soluble chitosan against S. aureus, Escherichia coli, and Salmonella typhi was evaluated by the conventional agar plate method at pH 7. The water-soluble product with Mw of 0.45 × 104 from initial chitosan of DD of 90% showed high moisture-absorption and moisture-retention capacities, and <2% concentration can completely inhibit the growth of these bacteria. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1724–1730, 2002
Co-reporter:Hua Zheng;Lina Zhang;Jinping Zhou
Journal of Applied Polymer Science 2002 Volume 86(Issue 7) pp:1679-1683
Publication Date(Web):5 SEP 2002
DOI:10.1002/app.11043
Regenerated cellulose/chitin blend films (RCCH) were satisfactorily prepared in 6 wt % NaOH/4 wt % urea aqueous solution by coagulating with 5 wt % CaCl2 aqueous solution then treating with 1 wt % HCl. The structure, miscibility, and mechanical properties of the RCCH films were investigated by infrared, scanning electron microscopy, ultraviolet spectroscopies, X-ray diffraction, tensile test, and differential scanning analysis. The results indicated that the blends were miscible when the content of chitin was lower than 40 wt %. Moreover, the RCCH blend film achieved the maximum tensile strength in both dry and wet states of 89.1 and 43.7 MPa, respectively, indicating that the tensile strength and water resistivity of the RCCH film containing 10–20 wt % chitin was slightly higher than that of the RC film unblended with chitin. Structural analysis indicated that strong interaction occurred between cellulose and chitin molecules caused by intermolecular hydrogen bonding. Compared to the mechanical properties of chitin film, those of the blend films containing 10–50 wt % chitin were significantly improved. This work provided a novel way to obtain directly chitin material blended in the aqueous solution. © 2002 Wiley Periodicals, Inc. J Appl Polym Sci 86: 1679–1683, 2002
Co-reporter:Qin Caiqin, Xiao Ling, Du Yumin, Shi Xiaowen, Chen Jiawei
Reactive and Functional Polymers 2002 Volume 50(Issue 2) pp:165-171
Publication Date(Web):January 2002
DOI:10.1016/S1381-5148(01)00111-0
A new cross-linked resin was prepared by an inverse emulsion method under the protection of amino group. The resin reacted with glycidyl trimethylammonium chloride to form the quaternary ammonium ion resin, whose chloride was exchanged with potassium borohydride to get the borohydride exchange resin (CBER). CBER was used as a new polymer-supported reducing agent for the reduction of carbonyl compounds to corresponding alcohols, and exhibited a relatively high chemoselectivity and possessed the advantage of easy work-up.
Co-reporter:Shuping Wu, Jiao Hu, Liuting Wei, Yumin Du, Xiaowen Shi, Hongbing Deng, Lina Zhang
Journal of Environmental Chemical Engineering (September 2014) Volume 2(Issue 3) pp:1568-1577
Publication Date(Web):1 September 2014
DOI:10.1016/j.jece.2014.07.001
A facile and environmentally benign method was developed to incorporate TiO2 into a chitosan–xylan polysaccharide network. The chitosan–xylan–TiO2 hybrid (CXTH) with highly porous structure was constructed via Schiff base linkages between the aldehyde groups on xylan chain and the amino groups on chitosan. The CXTH was characterized by FTIR, TGA, XRD, SEM and TEM. Moreover, the porous structure of CXTH could be controlled by employing nanoTiO2 particles as nanofillers. The results showed that the nanoTiO2 powders can significantly improve the porous structure of hybrid. The water absorption of CXTH reached 1507 wt% in purified water and 821 wt% in 0.9 wt% NaCl solution, respectively. The adsorption capabilities for heavy metals on CXTH was investigated as the function of pH, temperature, contact time and the initial concentration of metal ions. The maximum adsorption capacities of CXTH for Cu2+, Cr6+, Ni2+, Cd2+ and Hg2+ were 158.7, 97.1, 96.2, 78.1 and 76.3 mg g−1, respectively. Langmuir isotherm equation and the pseudo-second-order kinetic model illustrated that the adsorption was spontaneous and endothermic chemical adsorption. The regeneration experiments showed CXTH can be used effectively for numbers of adsorption–desorption cycles.
