Co-reporter:Yan-Ling Luo;Xue-Yin Zhang;Yuan Wang;Fang-Jie Han;Feng Xu;Ya-Shao Chen
Journal of Materials Chemistry B 2017 vol. 5(Issue 17) pp:3111-3121
Publication Date(Web):2017/05/03
DOI:10.1039/C7TB00073A
pH-Sensitive H-type multiblock copolymers, namely, poly(methacrylic acid)2-block-epoxidized hydroxyl-terminated polybutadiene-block-poly(methacrylic acid)2 (PMAA2-b-epoHTPB-b-PMAA2), were synthesized by atom-transfer radical polymerization and subsequent in situ epoxidation by peracetic acid and characterized by 1H NMR, FT-IR and SEC techniques. The impact of epoxidation on the physicochemical and biomedical properties of copolymer self-assembly micelle nanoparticles was investigated by fluorescence spectrometry, DLS, TEM and an MTT assay. The experimental results indicated that epoxidation resulted in the formation of more stable copolymer micelle nanoparticles with a lower critical micelle concentration, smaller micelle size, and higher loading capacity and encapsulation efficiency of drugs than those without epoxidation. In particular, epoxidized copolymer micelle nanoparticles exhibited reasonable pH sensitivity at a pH of 5.3–5.6. The hydrophobic anticancer drug paclitaxel (PTX) displayed faster release rates from epoxidized nanomicelles than from unepoxidized nanomicelles in a PBS solution of a pH of 4.8–6.6, whereas in PBS of a pH of 7.4 smaller amounts of PTX were released from epoxidized nanomicelles than from unepoxidized nanomicelles. Epoxidized copolymer nanomicelles were reasonably biodegradable after the drug was released, and their degradation rate was faster than that of their unepoxidized counterparts. An MTT assay was performed to determine the biocompatibility of epoxidized copolymer micelle nanoparticles and the anticancer activities of PTX-loaded nanomicelles, which were important for applications in the therapy of cancers as a controlled-release drug carrier.
Co-reporter:Feng Xu;Zhuo-Miao Cui;He Li
RSC Advances (2011-Present) 2017 vol. 7(Issue 12) pp:7431-7441
Publication Date(Web):2017/01/20
DOI:10.1039/C6RA26436K
Food safety has always been a topic that attracts attention. The residues of pesticides will directly or potentially affect and threaten human health when they are used to protect crops. Therefore, it is important to rapidly, promptly and accurately monitor pesticide residues in food. In this study, a novel nanohybrid composite with good electrochemical responses was developed, and it was prepared by the esterification reaction of hydroxyl-terminated polybutadiene (HTPB) with MWCNTs-COOH, followed by atom transfer radical polymerization of 4-acryloyloxybutyl(ethyl) ferrocene carboxylates with different spacers. The nanohybrid composites were characterized by FTIR, TGA, Raman, XRD, XPS, SEM and TEM techniques. Cyclic voltammetry (CV) determination showed that a longer spacer between the side ferrocene groups and main chains endowed the electrochemical modified electrodes with active electroresponse, obvious redox current and reversible electrochemical properties because of the faster electron transfer rates. The modified electrode sensor with a longer spacer was used to detect melamine and trichlorfon residues by CV and differential pulse voltammetry (DPV) techniques. The sensor had a good linear relationship over a wide concentration range, a maximal recovery of ca. 112.4% and a low detection limit of about 1.5 × 10−7 and 3.5 × 10−8 mol L−1, respectively.
Co-reporter:Feng Xu, He Li, Yan-Ling Luo, and Wei Tang
ACS Applied Materials & Interfaces 2017 Volume 9(Issue 6) pp:
Publication Date(Web):January 18, 2017
DOI:10.1021/acsami.6b16017
Novel well-defined redox-responsive ferrocene-containing amphiphilic block copolymers (PACMO-b-PAEFC) were synthesized by ATRP, with poly(N-acryloylmorpholine) (PACMO) as hydrophilic blocks and poly(2-acryloyloxyethyl ferrocenecarboxylate) (PAEFC) as hydrophobic blocks. The copolymers were characterized by FT-IR and 1H NMR spectroscopies and gel permeation chromatography, and the crystalline behavior was determined by X-ray diffraction and small-angle X-ray scattering. The results showed that the size of the lamellar crystals and crystallinity vary with the systematic compositions while the periodic structure of the lamellar stacks has no obvious change. These block copolymers could self-assemble and form globular nanoscaled core–shell micellar aggregates in aqueous solution. The reductive ferrocene groups could be changed into hydrophilic ferrocenium via mild oxidation, whereas the polymer micelles at the oxidation state could reversibly recover from their original states upon reduction by vitamin C. The tunable redox response was investigated and verified by transmission electron microscopy, ultraviolet–visible spectroscopy, cyclic voltammetry, and dynamic light scattering measurements. The copolymer micelles were used to entrap anticancer drug paclitaxel (PTX), with high drug encapsulation efficiency of 61.4%, while the PTX-loaded drug formulation exhibited oxidation-controlled drug release, and the release rate could be mediated by the kinds and concentrations of oxidants. MTT assay was performed to disclose the biocompatibility and security of the copolymer micelles and to assess anticancer efficiency of the PTX-loaded nanomicelles. The developed copolymer nanomicelles with reversible redox response are anticipated to have potential in targeted drug delivery systems for cancer therapy.Keywords: biomaterials; block copolymer; copolymer micelles; drug release; redox-stimuli response; self-assembly;
Co-reporter:Xue-Peng Wei, Yan-Ling Luo, Feng Xu, Ya-Shao Chen
Synthetic Metals 2016 Volume 215() pp:216-222
Publication Date(Web):May 2016
DOI:10.1016/j.synthmet.2016.02.023
•Sensitive conductive polymer composites were prepared via a simple blend process.•The conductive nanocomposites exhibited excellent electrical response properties.•The MWCNTs/PLA conductive composites had a low percolation threshold of ca 2.9 wt%.•The conductive films showed fast response, linear correlation, and stability.•The response hinged upon the PLA MW, the MWCNTs contents and vapor concentrations.The sensitive conductive polymer composites (SCPCs) have been attracting a great deal of research interest because of their unique response to external environmental stimuli. In this study, multiwalled carbon nanotubes/polylactic acid (MWCNTs/PLA) conductive composites were prepared by a physically blending method and fabricated into thin films. The dispersion behavior and morphological structure of the composites were characterized and confirmed by FTIR, SEM, TEM and UV–vis measurements. The influence of the mass fraction of MWCNTs and the molecular weight (MW) of PLA on conducting properties was investigated. The responses of the films against various organic vapors (polar and non-polar solvents) were measured by monitoring the change in resistance when exposed to the organic vapors. The experimental results revealed that the MWCNTs/PLA conductive composites had good film-forming properties, which showed a strong and selective response to polar chloroform vapor, with a low percolation threshold of about 2.9 wt%. The response intensities were enhanced with increasing the MW of PLA and decreasing the mass fraction of MWCNTs. The composite films exhibited fast response and favorable reversibility, reproducibility and stability, especially a detection limit as low as 50 ppm. Thus they could be used as gas sensors to detect the organic vapors in atmospheric environments.
Co-reporter:Yan-Ling Luo;Rui-Xue Bai;Feng Xu;Ya-Shao Chen;Hua Li
Journal of Materials Science 2016 Volume 51( Issue 3) pp:1363-1375
Publication Date(Web):2016 February
DOI:10.1007/s10853-015-9455-5
Novel multiwalled carbon nanotube graft polyethylene glycol-block-polystyrene copolymer nanohybrids (MWCNTs-g-PEG-b-PS) were prepared via atom transfer radical polymerization using carboxylated MWCNTs (MWCNTs–COOH) as a conductive carrier. The chemical structure and the compositions of graft copolymer nanohybrids were characterized by Fourier transform infrared spectroscopy, Raman spectroscopy, thermogravimetry, and gas chromatography, and the morphologies and dispersion behavior were observed by ultraviolet visible spectrophotometer, scanning electron microscope, and transmission electron microscope etc. The MWCNTs-g-PEG-b-PS-grafted copolymer nanohybrids were fabricated into conductive composite thin film sensors to investigate their responsiveness to benzene vapor. The influence of the molecular weights or compositional ratios of PEG and PS blocks on the conductivity of the conducting polymer nanohybrids and responsibility towards benzene vapor was investigated. The conducting polymer nanohybrid film sensors were demonstrated to possess the characteristics of quick response and good restorability, repeatability, and stability.
Co-reporter:Yan-Ling Luo;Mei Han;Feng Xu;Ya-Shao Chen ;Yong-Qin Zhang
Macromolecular Bioscience 2015 Volume 15( Issue 10) pp:1411-1422
Publication Date(Web):
DOI:10.1002/mabi.201500103
pH-Responsive H-type poly(methylacrylic acid-block-four hydroxyl terminated poly(butadiene-acrylobitrile)-block-poly(methylacrylic acid (PMAA2-b-HTPBN-b-PMAA2) block copolymers were synthesized via atom transfer radical polymerization and the follow-up hydrolysis, and characterized by 1H NMR, FT-IR and SEC. The block copolymers could self-assemble into nanoscale spherical core-shell micelle aggregates in aqueous solution, and the physicochemical properties depended on the system composition and pH media, with pH phase transition at 5.7–6.1. The copolymer micelle aggregates exhibited pH-triggered drug release and cytotoxicity, and could potentially be used as drug targeting release carriers.
Co-reporter:Yan-Ling Luo;Jun Zhang;Fang-Jie Han;Feng Xu;Ya-Shao Chen ;Ru Liu
Journal of Applied Polymer Science 2015 Volume 132( Issue 18) pp:
Publication Date(Web):
DOI:10.1002/app.41877
ABSTRACT
Thermoresponsive poly(N-isopropyl acrylamide) (PNIPAM)-block-hydroxy-terminated polybutadine-block-PNIPAM triblock copolymers were synthesized by atom transfer radical polymerization; this was followed by the in situ epoxidation reaction of peracetic acid. The copolymers were characterized by 1H-NMR, Fourier transform infrared spectroscopy, and size exclusion chromatography measurements, and their physicochemical properties in aqueous solution were investigated by surface tension measurement, fluorescent spectrometry, ultraviolet–visible transmittance, transmission electron microscopy observations, dynamic light scattering, and so on. The experimental results indicate that the epoxidized copolymer micelle aggregates retained a spherical core–shell micelle structure similar to the control sample. However, they possessed a decreased critical aggregate concentration (CAC), increased hydrodynamic diameters, and a high aggregation number and cloud point because of the incorporation of epoxy groups and so on. In particular, the epoxidized copolymer micelles assumed an improved loading capacity and entrapment efficiency of the drug, a preferable drug-release profiles without an initial burst release, and a low cytotoxicity. Therefore, they were more suitable for the loading and delivery of the hydrophobic drug as a controlled release drug carrier. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41877.
Co-reporter:Feng Xu, Shuang Guo, Yan-Ling Luo
Materials Chemistry and Physics 2014 Volume 145(1–2) pp:222-231
Publication Date(Web):15 May 2014
DOI:10.1016/j.matchemphys.2014.02.006
•Novel THTBN/MWNTs-OH PU films were prepared via in-situ coupling reaction.•The structure, morphology and dispersion behavior were examined.•The films displayed good response, selectivity, reversibility and stability.•The response depended upon the loading of MWNTs-OH and vapor concentrations.•The composite films can be used as sensors to detect benzene and toluene vapors.Novel polyurethane (PU) conducting composite thin films based on tetrahydroxyl-terminated poly(butadiene-co-acrylonitrile) (THTBN) and hydroxyl-functionalized multi-walled carbon nanotubes (MWNTs-OH), were prepared via an in-situ coupling reaction route between hydroxyl groups and isocyanate groups. The chemical and crystal structures were characterized by Fourier transform infrared spectra (FTIR) and X-ray diffraction (XRD). The morphologies and the dispersion behavior of THTBN/MWNTs-OH were examined by scanning electron microscope (SEM), transmission electron microscopy (TEM) and UV–Vis measurements. The influence of MWNTs-OH loading amount on conducting properties and response to some volatile organic compounds (VOCs) especially benzene and toluene was investigated. The experimental results indicated that MWNTs-OH was tightly encapsulated by PU moieties and homogeneously dispersed in the PU moieties. The as-prepared THTBN/MWNTs-OH PU conducting thin films exhibited strong and selective response to nonpolar benzene and toluene vapors, and the response depends on the loading of MWNTs-OH and VOC vapor concentrations. The improvement in dispersity and sensing properties were closely correlated with the chemical linkage of MWNTs-OH in the THTBN matrices through bridging molecules HDI. The developed PU conducting thin films had fast response and reversibility, significant reproducibility and long-term stability. Therefore, they had a possibility as a candidate of volatile organic solvent vapor sensors.
Co-reporter:Yan-Ling Luo;Rui-Juan Huang;Feng Xu;Ya-Shao Chen
Journal of Materials Science 2014 Volume 49( Issue 22) pp:7730-7741
Publication Date(Web):2014 November
DOI:10.1007/s10853-014-8483-x
pH-Sensitive biodegradable polymethacrylic acid-block-polylactic acid-block-polymethacrylic acid (PMAA2-b-PLA-b-PMAA2) H-type multiblock copolymers were synthesized by atom transfer radical polymerization. The copolymer structure and molecular weight were characterized by FT-IR, 1H NMR, and gel permeation chromatography. The physicochemical characterization revealed that the copolymers could spontaneously form spherical core–shell micelles in aqueous solution, with critical aggregation concentration of about 19.7–32.5 mg L−1 and the hydrodynamic diameters below 200 nm. Zeta potentials measurements disclosed that the copolymer micelles were negatively charged due to ionized carboxyl groups in various PBS solutions. The H-type block copolymer micelles exhibited pH- sensitivity, as expected; and the hydrophobic anticancer drugs, 10-hydroxycamptothecin, and paclitaxel, had faster release rate in PBS solution of pH 5.6–7.4 than in PBS of pH 1.4, which was important for applications in the therapy of small intestine cancers. The copolymer micelle aggregates were proved to be biodegradable, and the degradation rates changed with copolymer compositions and environmental media. The micelle drug formulation indicated pH-dependent cytotoxicity and was thus capable of effectively killing the intestinal cells while avoiding doing harm to stomach. The biodegradable pH-sensitive PMAA2-b-PLA-b-PMAA2 H-type copolymer micelles can be used as water-insoluble drug targeting release carriers for targeted treatment of intestine cancers.
Co-reporter:Xiao-Li Yang;Feng Xu;Ya-Shao Chen
Pharmaceutical Research 2014 Volume 31( Issue 2) pp:291-304
Publication Date(Web):2014 February
DOI:10.1007/s11095-013-1160-y
Block copolymer micelles are extensively used as drug controlled release carriers, showing promising application prospects. The comb or brush copolymers are especially of great interest, whose densely-grafted side chains may be important for tuning the physicochemical properties and conformation in selective solvents, even in vitro drug release. The purpose of this work was to synthesize novel block copolymer combs via atom transfer radical polymerization, to evaluate its physicochemical features in solution, to improve drug release behavior and to enhance the bioavailablity, and to decrease cytotoxicity.The physicochemical properties of the copolymer micelles were examined by modulating the composition and the molecular weights of the building blocks. A dialysis method was used to load hydrophobic camptothecin (CPT), and the CPT release and stability were detected by UV–vis spectroscopy and high-performance liquid chromatography, and the cytotoxicity was evaluated by MTT assays.The copolymers could self-assemble into well-defined spherical core-shell micelle aggregates in aqueous solution, and showed thermo-induced micellization behavior, and the critical micelle concentration was 2.96–27.64 mg L−1. The micelles were narrow-size-distribution, with hydrodynamic diameters about 128–193 nm, depending on the chain length of methoxy polyethylene glycol (mPEG) blocks and poly(N-isopropylacrylamide) (PNIPAM) graft chains or/and compositional ratios of mPEG to PNIPAM. The copolymer micelles could stably and effectively load CPT but avoid toxicity and side-effects, and exhibited thermo-dependent controlled and targeted drug release behavior.The copolymer micelles were safe, stable and effective, and could potentially be employed as CPT controlled release carriers.
Co-reporter:Yan-Ling Luo, Xiao-Li Yang, Feng Xu, Ya-Shao Chen, Bin Zhang
Colloids and Surfaces B: Biointerfaces 2014 Volume 114() pp:150-157
Publication Date(Web):1 February 2014
DOI:10.1016/j.colsurfb.2013.09.043
•Block copolymers with different molecular architectures were synthesized via ATRP.•The copolymers exhibited thermo-sensitive self-assembly and CPT release behavior.•The multiblock copolymers had more regular spherical core–shell micelle architecture.•The multiblock copolymers had better physicochemical properties and CPT release.•The copolymer micelles are harmless, and can be employed as drug release carriers.Two kinds of thermo-sensitive poly(N-isoproplacrylamide) (PNIPAM) block copolymers, AB4 four-armed star multiblock and linear triblock copolymers, were synthesized by ATRP with hydroxyl-terminated polybutadiene (HTPB) as central blocks, and characterization was performed by 1H NMR, FT-IR and SEC. The multiblock copolymers could spontaneously assemble into more regular spherical core–shell nanoscale micelles than the linear triblock copolymer. The physicochemical properties were detected by a surface tension technique, nano particle analyzer, TEM, DLS and UV–vis measurements. The multiblock copolymer micelles had lower critical micelle concentration than the linear counterpart, TEM size from 100 to 120 nm and the hydrodynamic diameters below 150 nm. The micelles exhibited thermo-dependent size change, with low critical solution temperature about 33–35 °C. The characteristic parameters were affected by the composition ratios, length of PNIPAM blocks and molecular architectures. The camptothecin release demonstrated that the drug release was thermo-responsive, accompanied by the temperature-induced structural changes of the micelles. MTT assays were performed to evaluate the biocompatibility or cytotoxicity of the prepared copolymer micelles.
Co-reporter:Yan-Ling Luo;Xiao-Li Yang;Feng Xu;Ya-Shao Chen;Xu Zhao
Colloid and Polymer Science 2014 Volume 292( Issue 5) pp:1061-1072
Publication Date(Web):2014 May
DOI:10.1007/s00396-013-3149-9
pH-sensitive poly(methacrylic acid)-block-hydroxyl-terminated polybutadiene-block-poly(methacrylic acid) block copolymers were synthesized by atom transfer radical polymerization of t-butyl methacrylate and follow-up acidolysis. The copolymers can spontaneously assemble into stable and nearly spherical micelle aggregates in aqueous solution, with hydrodynamic diameters (Dh) from 51 to 92 nm and critical micelle concentration of 3.90–7.76 mg L−1. Zeta potentials were found to be increased with increasing (monomer)/(initiator) molar ratios. A pH-dependent phase behavior is produced at approximately 5.4–5.6, as determined by Dh and I335/I332 fluorescence intensity ratios. The in vitro camptothecin (CPT) release was compositional and pH dependent, and the cumulative CPT release below pH 7.2 was higher than that in pH 7.4. They could inhibit the premature burst CPT release. The copolymer micelles were low in cytotoxicity even at a micellar concentration of 800 mg L−1, and therefore they may be used as potential drug-delivery carriers.
Co-reporter:Yan-Ling Luo, Li-Li Chen, Yan Miao, and Feng Xu
Industrial & Engineering Chemistry Research 2013 Volume 52(Issue 4) pp:1571
Publication Date(Web):December 20, 2012
DOI:10.1021/ie3024164
Novel AB4-type polyurethane (PU) micelle-like amphiphilic block copolymers consisting of hydroxyl-functionalized carboxyl-terminated poly(butadiene-co-acrylonitrile) (f-CTBN) as the hydrophobic cores and methoxy poly(ethylene glycol) (MPEG) as the hydrophilic branched blocks were synthesized via esterification, followed by coupling reaction. Their chemical structure and molecular weight were characterized by FTIR, NMR, and SEC measurements. The block copolymers could easily self-assemble to form core–shell micelle nanoparticles in various media. The micelles bear a critical micelle concentration (CMC) in a range from 0.740 to 6.310 mg L–1 and were very stable even in PBS solutions. The TEM and DLS findings revealed that the micelles were almost spherical and narrow-size-distribution, with TEM mean diameters from 13 to 24 nm, and average hydrodynamic diameter about 124–151 nm. All these depended on chain lengths and compositional ratios of hydrophilic MPEG blocks. The drug loading and in vitro release indicated that the self-assembled micelle nanoparticles could effectively load hydrophobic prednisone, with encapsulation capacity of about 27–30%, and the drug release from the nanoparticles was dependent on MPEG chain lengths and the molar ratios of f-CTBN to MPEG. Cytotoxicity assays disclosed that the as-prepared block copolymer micelle nanoparticles exhibit good biocompatibility and could be employed as potential drug controlled release carriers.
Co-reporter:Qing-Bo Wei;Feng Fu;Yu-Qi Zhang;Rong-Xuan Ma
Journal of Applied Polymer Science 2013 Volume 129( Issue 2) pp:806-814
Publication Date(Web):
DOI:10.1002/app.38788
Abstract
A novel pH- and temperature-responsive hydrogel composed of carboxymethyl chitosan (CMC) and polyacrylamide (PAM) semi-interpenetrating polymer networks (semi-IPNs) was synthesized by a crosslinking copolymerization route in the presence of N,N-methylene bisacrylamide and potassium persulfate. The structure of the CMC/PAM hydrogels was characterized by Fourier transform infrared spectroscopy, and the morphologies were observed by scanning electron microscopy. The swelling kinetics investigations demonstrated that the equilibrium swelling ratios (ESRs) of the semi-IPN hydrogels depended on the compositional ratios, pH values of the buffer solutions, and temperature. The ESR values increased with increasing CMC contents and pH values; this was in agreement with the maximum theoretical water contents fitted by the swelling kinetic data. The CMC/PAM hydrogels complied with Fickian behavior at pH 1.4 and non-Fickian behavior at pH 11.7 in the buffer solutions. These hydrogels displayed thermosensitivities that were different from those of common thermoresponsive gels. The swelling was enhanced when the temperature of the media was increased up to 40°C; this was followed by a reduction. Therefore, the swelling behavior of the CMC/PAM hydrogels could be controlled and modulated by means of the compositional ratios of CMC to acrylamide, pH values of the buffer solutions, and temperature. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013
Co-reporter:Yan-Ling Luo;Xiao-Li Yang;Feng Xu;Ya-Shao Chen ;Zhuo-Ma Ren-Ting
Journal of Applied Polymer Science 2013 Volume 130( Issue 6) pp:4137-4146
Publication Date(Web):
DOI:10.1002/app.39530
ABSTRACT
A novel A2BA2-type thermosensitive four-armed star block copolymer, poly(N-isopropyl acrylamide)2-b-poly(lactic acid)-b-poly(N-isopropyl acrylamide)2, was synthesized by atom transfer radical polymerization and characterized by 1H-NMR, Fourier transform infrared spectroscopy, and size exclusion chromatography. The copolymers can self-assemble into nanoscale spherical core–shell micelles. Dynamic light scattering, surface tension, and ultraviolet–visible determination revealed that the micelles had hydrodynamic diameters (Dh) below 200 nm, critical micelle concentrations from 50 to 55 mg/L, ζ potentials from −7 to −19 mV, and cloud points (CPs) of 34–36°C, depending on the [Monomer]/[Macroinitiator] ratios. The CPs and ζ potential absolute values were slightly decreased in simulated physiological media, whereas Dh increased somewhat. The hydrophobic camptothecin (CPT) was entrapped in polymer micelles to investigate the thermo-induced drug release. The stability of the CPT-loaded micelles was evaluated by changes in the CPT contents loaded in the micelles and micellar sizes. The MTT cell viability was used to validate the biocompatibility of the developed copolymer micelle aggregates. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4137–4146, 2013
Co-reporter:Qing-Bo Wie;Feng Fu;Lou-Jun Gao;Yan-Wei Song
Colloid Journal 2013 Volume 75( Issue 1) pp:34-39
Publication Date(Web):2013 January
DOI:10.1134/S1061933X13010146
Polyacrylamide grafted poly(vinyl alcohol)/polyvinylpyrrolidone (PAM-g-PVA/PVP) semi-interpenetrating network (semi-IPN) hydrogels were designed and prepared via a simple free radical polymerization reaction process initiated by a PVA-(NH4)2Ce(NO3)6 redox system. The structure of the PAM-g-PVA/PVP semi-IPNs was characterized by a Fourier transform infrared spectroscopy. The morphologies of PAM-g-PVA/PVP hydrogels and PAM-g-PVA/PVP/Ag nanocomposite hydrogels were examined by scanning electron microscopy and transmission electron microscopy (TEM). The experimental results indicated that the PAM, PVA or PVP chains can efficiently act as stabilizing agents for Ag nanoparticles. TEM investigation of sample morphology showed the presence of nearly spherical-, square- or rectangular-shaped Ag nanoparticles with diameters ranging from 10 to 60 nm. The characteristic surface plasmon resonance band appeared at 390–400 run as a result of the immobilization of Ag nanoparticles within the hydrogel matrices. The self-assembly of Ag nanoparticles and the swelling behavior of the resulting nanocomposites can be controlled and modulated by altering the mole fraction of PVP in the PAM-g-PVA/PVP semi-IPNs.
Co-reporter:Qing-Bo Wei;Feng Fu;Lou-Jun Gao;Yan-Wei Song
Colloid Journal 2013 Volume 75( Issue 3) pp:356
Publication Date(Web):2013 May
DOI:10.1134/S1061933X13070016
Co-reporter:Feng Xu;Shu-Zhen Zheng
Journal of Polymer Science Part A: Polymer Chemistry 2013 Volume 51( Issue 20) pp:4429-4439
Publication Date(Web):
DOI:10.1002/pola.26859
ABSTRACT
Thermosensitive polylactide-block-poly(N-isopropylacrylamide) (t-PLA-b-PNIPAAm) tri-armed star block copolymers were synthesized by atom transfer radical polymerization (ATRP) of monomer NIPAAm using t-PLA-Cl as macroinitiator. The synthesis of t-PLA-Cl was accomplished by esterification of star polylactides (t-PLA) with 2-chloropropionyl chloride using trimethylolpropane as a center molecule. FT-IR, 1H NMR, and GPC analyses confirmed that the t-PLA-b-PNIPAAm star block copolymers had well-defined structure and controlled molecular weights. The block copolymers could form core-shell micelle nanoparticles due to their hydrophilic-hydrophobic trait in aqueous media, and the critical micelle concentrations (CMC) were from 6.7 to 32.9 mg L−1, depending on the system composition. The as-prepared micelle nanoparticles showed reversible phase changes in transmittance with temperature: transparent below low critical solution temperature (LCST) and opaque above the LCST. Transmission electron microscopy (TEM) observations revealed that the micelle nanoparticles were spherical in shape with core-shell structure. The hydrodynamic diameters of the micelle nanoparticles depended on copolymer compositions, micelle concentrations and media. MTT assays were conducted to evaluate cytotoxicity of the camptothecin-loaded copolymer micelles. Camptothecin drug release studies showed that the copolymer micelles exhibited thermo-triggered targeting drug release behavior, and thus had potential application values in drug controlled delivery. © 2013 Wiley Periodicals, Inc. J. Polym. Sci., Part A: Polym. Chem. 2013, 51, 4429–4439
Co-reporter:Feng Xu;Shu-Zhen Zheng;Ting-Ting Chen
Macromolecular Research 2013 Volume 21( Issue 9) pp:977-986
Publication Date(Web):2013/09/01
DOI:10.1007/s13233-013-1112-8
Co-reporter:Yan-Ling Luo;Chang-Hu Zhang;Feng Xu;Ya-Shao Chen
Polymers for Advanced Technologies 2012 Volume 23( Issue 3) pp:551-557
Publication Date(Web):
DOI:10.1002/pat.1916
Abstract
Highly branched polyurethane (PU) scaffolds that match mechanical properties are the preferred tissue engineering materials, which is composed of a multi-hydroxyl-terminated poly(butadiene-co-acrylonitrile) (THTPBA) prepolymer and poly(ethylene glycol) (PEG) via 1,6-hexamethylene diisocyanate as anchor molecule. This combination is anticipated to influence or alter hydrophilicity or hydrophobicity, degradation and haemocompatibility of the PEG-derived PUs. Hence, the surface properties, degradability, mechanical and biomedical properties of the PUs were scrutinized and assessed by FTIR, contact angles, gravimetry, stress-strain measurement and haemolysis, platelet adhesion as well as methyl tretrazolium (MTT) assays. The experimental results indicated that the incorporation of THTPBA can mediate the degradation rate, which took place at the urethane or ester bonds in polymer chains. The haemolytic activity, platelet activation, and MTT investigations elicited that the component ratios of THTPBA to PEG had important influence on biomedical properties, including in vitro blood compatibility, cytotoxicity, and cell cycle or apoptosis of the PU scaffolds. The tensile stress-strain investigations showed that the highly branched architecture offered high elastic modulus and mechanical strength. The novel PU scaffolds with highly branched architecture exhibited improved mechanical properties and biocompatibility as well as low toxicity by regulating proper component ratios, and are expected to be employed in tissue engineering, or as potential candidates for other blood-contacting applications. Copyright © 2011 John Wiley & Sons, Ltd.
Co-reporter:Yan-Ling Luo;Wei Yu;Feng Xu
Polymer Bulletin 2012 Volume 69( Issue 5) pp:597-620
Publication Date(Web):2012 September
DOI:10.1007/s00289-012-0774-2
pH-sensitive hydrophilic poly(methacrylic acid)-b-poly(ethylene glycol)-b-poly(methacrylic acid) (PMAA-b-PEG-b-PMAA) triblock copolymers were synthesized through atom transfer radical polymerization, and were characterized by FT-IR, 1H NMR, and GPC. The as-synthesized polymers can self-assemble into stable and almost spherical nanomicelles in aqueous solution with an average size range from 18 to 89 nm, depending on the micellar concentrations, while they assumed well-defined spherical morphologies in PBS solutions. The micellization behavior in different media was investigated by a fluorescence spectroscopy technique, UV–Vis transmittance, and dynamic light scattering measurements. The critical micelle concentration and size of the micelles decrease with the increasing the length or molecular weights of PEG and PMAA chains. A pH-dependent phase transition behavior produces at a pH value of about 5.2, and the stable pH micellization behavior varied within a narrow pH range from ca. 4.8 to 7.4. These triblock copolymers are generally low cytotoxicity at a micellar concentration below 400 mg L−1, as revealed by the MTT assay. The prednisone release and release kinetics studies disclosed that these pH-sensitive polymeric micelles are good carriers for the drug delivery.
Co-reporter:Yan-Ling Luo;Wei Yu;Feng Xu;Li-Li Zhang
Journal of Polymer Science Part A: Polymer Chemistry 2012 Volume 50( Issue 10) pp:2053-2067
Publication Date(Web):
DOI:10.1002/pola.25980
Abstract
A novel double brush-shaped copolymer with amphiphilic polyacrylate-b-poly(ethylene glycol)-b-poly acrylate copolymer (PA-b-PEG-b-PA) as a backbone and thermosensitive poly(N-isopropylacrylamide) (PNIPAM) long side chains at both ends of the PEG was synthesized via an atom transfer radical polymerization (ATRP) route, and the structure was confirmed by FTIR, 1H NMR, and SEC. The thermosensitive self-assembly behavior was examined via UV-vis, TEM, DLS, and surface tension measurements, etc. The self-assembled micelles, with low critical solution temperatures (LCST) of 34–38 °C, form irregular fusiform and/or spherical morphologies with single, double, and petaling cores in aqueous solution at room temperature, while above the LCST the micelles took on more regular and smooth spherical shapes with diameter ranges from 45 to 100 nm. The micelle exhibits high stabilities even in simulated physiological media, with low critical micellization concentration (CMC) up to 5.50, 4.89, and 5.05 mg L−1 in aqueous solution, pH 1.4 and 7.4 PBS solutions, respectively. The TEM and DLS determination reveled that the copolymer micelle had broad size distribution below its LCST while it produces narrow and homogeneous size above the LCST. The cytotoxicity was investigated by MTT assays to elucidate the application potential of the as-prepared block polymer brushes as drug controlled release vehicles. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012
Co-reporter:Yun-Fei Nan;Feng Xu;Ya-Shao Chen ;Hong-Wei Di
Polymers for Advanced Technologies 2011 Volume 22( Issue 6) pp:802-810
Publication Date(Web):
DOI:10.1002/pat.1581
Abstract
This work reported the hydrophilicity, hemocompatibility, and cytotoxicity of novel polyurethane (PU) scaffolds for tissue engineering, especially the hydrolysis effect of a soft-segmented component, a hydrolytically-modified hydroxyl-terminated poly(butadiene-co-acrylonitrile) (h-HTBN), on these properties. The PU copolymers were prepared by coupling poly(ethylene glycol) (PEG) with the h-HTBN together with the help of 1,1-methylene bis-(4-isocyanatocyclohexane) as a bridging reagent. The structure of PU copolymers was characterized by Fourier transformation infrared spectrometry (FTIR). The experimental results indicated that the hydrolytically-modified HTBN increases water absorption and decreases water contact angles, improving surface hydrophilicity. The synthesized h-HTBN/PEG PU copolymers display low hemolysis activity, and a little amount of platelet adhesion and activation, implying good compatibility. The methyl tretrazolium (MTT) assays elicited that the cytotoxicity is related to the component ratios of h-HTBN to PEG and the hydrolysis modification of HTBN. The PU scaffolds can be employed as potential candidates for blood contacting applications. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:Yan-Ling Luo;Yun-Fei Nan;Feng Xu;Ya-Shao Chen ;Hong-Wei Di
Polymers for Advanced Technologies 2011 Volume 22( Issue 11) pp:1478-1486
Publication Date(Web):
DOI:10.1002/pat.1631
Abstract
The phase behavior of the as-prepared polyether polyurethane (PU) elastomers was investigated by dynamic mechanical analysis (DMA), polarized optical microscope (POM), and atomic force microscopy (AFM). This PU copolymers were composed of different compositions of two soft segments, poly(ethylene glycol) (PEG) and hydrolytically modified hydroxyl-terminated poly(butadiene-co-acrylonitrile) (h-HTBN) oligomers. The microphase separation behavior is confirmed to occur between soft and hard segments as well as soft and soft segments as the h-HTBN is incorporated into the PU system, depending on soft-soft and/or soft-hard microdomain composition, molecular weight (MW) of PEG, and hydrolysis time of HTBN. The driving force for this phase separation is mainly due to the formation of inter- and intramolecular hydrogen bonding interaction. The PU-70, PU-50 samples with non-reciprocal composition seem to exhibit larger microphase separation than any other PU ones. The hydrolysis degradation, thermal stability, and mechanical properties of the copolymers were assessed by gravimetry, scanning electron microscope (SEM), thermal gravity analysis (TGA), and tensile test, respectively. The experimental results indicated that the incorporation of h-HTBN soft segment into PEG as well as low MW of PEG leads to increased thermal and degradable stability based on the intermolecular hydrogen bond interaction. The PU-70 and PU-50 copolymers exhibit better mechanical properties such as high flexibility and high ductility because of their larger microphase separation architecture with the hard domains acting as reinforcing fillers and/or physical crosslinking agents dispersed in the soft segment matrix. Copyright © 2009 John Wiley & Sons, Ltd.
Co-reporter:Yan-Ling Luo;Li-Li Zhang;Feng Xu;Ting-Yu Ruan
Polymer Science, Series A 2011 Volume 53( Issue 1) pp:37-43
Publication Date(Web):2011 January
DOI:10.1134/S0965545X11010111
A new route was proposed to synthesize polyethylene glycol-tethered polymethacrylic acid (viz., PEG-tethered PMAA or PEG-t-PMAA) hydrogels based on a macromolecular azo initiator (MAI), PEG-attached azo initiator. The preparation of the MAI was accomplished by coupling PEG with 2,2-azobis[2-methyl-N-(2-hydroxyethyl)propionamide] (AMHP) using 1,1-methylene bis-(4-isocyanato-cyclohexane) (H12MDI) as bridging molecules. The structure and morphologies of the resulting hydrogels were characterized by FTIR and SEM. The pH and ionic strength responses were investigated by swelling measurements, depending on molecular weight (MW) of PEG, molar ratios of isocyanate-terminated PEG to AMHP and mass percentage of the as-prepared MAIs. The PEG-t-PMAA hydrogels synthesized by 100 wt% PEG1000-attached azo initiators and a molar ratio 2 of -NCO-terminated PEG to AMHP exhibit more remarkable pH and ionic strength response than any other hydrogels. The driving force of swelling is believed to be mainly due to the porosity and dissociation balance of PMAA gels as well as gel compositions, while the deswelling behavior may be correlated with the decrease in osmotic pressure caused by the so-called “charge screening effect“ of the cations. The PEG-t-PMAA hydrogels are expected to find specific applications in oral drug delivery and tissue engineering.
Co-reporter:Feng Xu;Ting-Ting Yan
Macromolecular Research 2011 Volume 19( Issue 12) pp:1287-1295
Publication Date(Web):2011 December
DOI:10.1007/s13233-011-1209-x
The thermo-sensitive amphiphilic block copolymer poly(N-isopropylacrylamide)-block-poly(D,L-lactide) (PNIPAAm-b-PLA) was synthesized using a simple free radical copolymerization route based on a bifunctional initiator, 2,2-azobis(2-methylpropion amidine) dihydrochloride followed by the ring-opening polymerization of D,L-actide in the presence of a Sn(Oct)2 catalyst. The chemical structure of the PNIPAAm-b-PLA copolymers was verified using Fourier transform-infrared spectrophotometry and nuclear magnetic resonance, and the molecular weight and polydispersity index were examined using gel permeation chromatography. The amphiphilic PNIPAAm-b-PLA block copolymers could self-assemble into spherically shaped micelles in an aqueous solution with a transmission electron microscopy diameter range of 40–56 nm and a dynamic laser scattering hydrodynamic diameter of 90–200 nm. This behavior depends on the environmental temperature, the hydrophobic interactions among PNIPAAm molecular chains, the intermolecular hydrogen bonding between the PNIPAAm chains and water molecules, and the intramolecular hydrogen bonding between the -CONH2 groups. The copolymers held a critical micellization concentration of 4.93–7.21 mg·L−1 and a low critical solution temperature of 31.15–32.62 °C being more or less affected by their compositions, PLA or PNIPAAm block length, and polymerization temperature. The as-prepared PNIPAAm-b-PLA block polymers are anticipated to be applied as candidate drug release carriers.
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Co-reporter:Yan-Ling Luo;Yan Miao;Feng Xu
Macromolecular Research 2011 Volume 19( Issue 12) pp:1233-1241
Publication Date(Web):2011 December
DOI:10.1007/s13233-011-1211-3
Two types of polyurethanes with alternating and random block architectures, hydroxyl-terminated liquid polybutadiene and poly(ethylene glycol) block copolymers (HTPB-alt-PEG and HTPB-co-PEG), were synthesized using a coupling reaction route between the hydroxyl groups and the isocyanate groups. The chemical and crystal structures were characterized using Fourier transform-infrared spectroscopy (FTIR) and X-ray diffraction, while phase behavior was examined using scanning electron microscopy (SEM) and differential scanning calorimetry. The biodegradation in a simulated human body fluid was investigated through mass loss, SEM, and FTIR. The experimental results indicated that all of the polyurethane samples bore the microphase separation structure, and the separation degree depended on the sequence structure and molecular weight (MW) of PEG and further affected their in vitro degradation. The driving force was related to the restricted movement of the molecular segments, the crystallization of the soft/hard phases, and/or the hydrogen bonding interactions between the hard segments. The surface morphological change of the degraded samples further demonstrated that the degradation became serious as the PEG MW increased and that the random block copolymers decomposed more easily than the alternating copolymers. The block polymer materials are expected to be incorporated into specific applications in related biomedical fields.
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Co-reporter:Yan-Ling Luo, Bi-Xia Wang, Feng Xu
Sensors and Actuators B: Chemical 2011 Volume 156(Issue 1) pp:12-22
Publication Date(Web):10 August 2011
DOI:10.1016/j.snb.2011.03.067
A series of multi-walled carbon nanotubes/polyurethane (MWNTs/PU) composite conducting dispersoids were prepared via an in situ coupling reaction among linear hydroxyl-terminated polymer diols, 1,6-hexamethylene diisocyanate (HDI) and various chain extenders. The composite conducting thin films were formed by spin-coating and depositing the dispersoids onto comb-like electrode substrates. The resulting structure and the dispersion quality of MWNTs in the dispersoids were examined by means of FTIR, XRD, TEM, SEM and UV–vis analyses. The response of the as-prepared films toward some volatile organic solvent vapors such as benzene, anhydrous ether, acetone and chloroform was evaluated. The experimental results indicated that the composite conducting films constructed by hydroxyl-terminated poly(butadiene-co-acrylonitrile), trimethylolpropane, and MWNTs–OH bear better vapor responsiveness. The dispersion behavior of MWNTs in the dispersoids, types of MWNTs and soft–hard segmental compositions are believed to be closely related with the sensing properties of the films. In particular, the chemical linkage of MWNT–OH with HDI in the PU matrix is expected to improve the dispersivity and further to enhance the sensing properties of the composite sensors. The vapor sensing properties well reveal that these materials have a possibility as a candidate of volatile organic solvent vapor sensors.
Co-reporter:Yan-Ling Luo;Feng Xu;Qiang-Suo Feng;Ya-Shao Chen ;Chao Ma
Journal of Biomedical Materials Research Part B: Applied Biomaterials 2010 Volume 92B( Issue 1) pp:243-254
Publication Date(Web):
DOI:10.1002/jbm.b.31511
Abstract
A novel nanohybrid hydrogel was in situ prepared by means of a free radical crosslinking polymerization route of methacrylic acid in the presence of multi-walled carbon nanotubes (MWCNTs). The structural and morphological characterizations revealed that poly(methacrylic acid) networks (PMAA) closely covered the MWCNTs, and a MWCNT-well-dispersed nanohybrid hydrogel was formed. The addition of MWCNTs strikingly improved pH response and mechanical properties, depending on the component ratios and particle sizes of MWCNTs as well as crosslinker concentrations. The swelling rate was obviously faster than that of the pure PMAA hydrogel. The hydrophilic nature of polyelectrolytes, the capillarity effect, cation-π or charge-transfer interaction and hydrogen bonds, as well as a subtle balance among these interactions were adopted to interpret the above swelling behavior. Load transfer to the MWCNTs in the networks played important part in compression mechanical improvements. MTT assays were adopted to evaluate the cytocompatibility of the developed biomaterials. This smart hydrogel is expected to be used as potential candidate for specific biological applications. © 2009 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater 2010
Co-reporter:Yan-Ling Luo, Li-Hua Fan, Feng Xu, Yao-Shao Chen, Chang-Hu Zhang, Qing-Bo Wei
Materials Chemistry and Physics 2010 120(2–3) pp: 590-597
Publication Date(Web):
DOI:10.1016/j.matchemphys.2009.12.002
Co-reporter:Yanling Luo;Changhu Zhang;Feng Xu;Yashao Chen;Lihua Fan
Journal of Materials Science 2010 Volume 45( Issue 7) pp:1866-1877
Publication Date(Web):2010 April
DOI:10.1007/s10853-009-4171-7
Novel polyurethane (PU) scaffold materials were designed and prepared on the basis of a coupling reaction between tetra-hydroxyl-terminated poly(butadiene-co-acrylonitrile) prepolymer (THTPBA) and poly(ethylene glycol) (PEG) via 1,6-hexamethylene diisocyanate as anchor molecule. The hydrophilicity, degradability, mechanical, and biomedical properties of the THTPBA/PEG PU materials were scrutinized by swelling and goniometry, FTIR and gravimetry methods, tensile stress–strain measurements and hemolysis, platelet activation, dynamic (erythrocyte aggregation) and static coagulation as well as MTT assays. The experimental results indicated that the hydrophilicity and mass loss were enhanced with increased concentrations and molecular weight (MW) of PEG. The degradation may be attributable to the cleavage of urethane or ester bonds in polymer chains. The in vitro blood compatibility and MTT cytotoxicity investigations elicited that the MW of PEG and mass ratios of THTPBA to PEG had important influence on the biomedical properties. The tensile stress–strain investigations showed that the highly crosslinked architecture offered high elastic modulus and mechanical strength. The PU scaffolds with proper component ratios and MW of PEG exhibited improved mechanical properties and biocompatibility as well as low toxicity, and can be employed as potential candidates for blood-contacting applications.
Co-reporter:Yan-Ling Luo;Feng Xu;Ya-Shao Chen;Chun-Yang Jia
Polymer Bulletin 2010 Volume 65( Issue 2) pp:181-199
Publication Date(Web):2010 July
DOI:10.1007/s00289-010-0248-3
Silver nanoparticles (AgNPs) with controlled size and size distribution were prepared by an in situ chemical reduction route based on a microreactor template composed of poly(acrylamide-co-N-vinylpyrrolidone)/chitosan semi-interpenetrating network hydrogels, P(AAm-co-NVP)/CS semi-IPN, in the presence of sodium hypophosphite. The characterization of structures and morphologies of the as-fabricated P(AAm-co-NVP)/CS–Ag nanocomposite hydrogels was conducted on a Fourier transformation infrared spectroscopy (FTIR), scanning electron microscope (SEM), transmission electron microscope (TEM), and UV–vis spectrometer. The effect of various component proportions of the reactants on formation of AgNPs and swelling of the resulting P(AAm-co-NVP)/CS–Ag nanocomposite hydrogels was investigated. The experimental results indicated that the Ag grains were uniformly dispersed within P(AAm-co-NVP)/CS hydrogel networks in a spherical shape, and were stabilized by the semi-IPN structure and a complexation and/or electrostatic interaction between Ag+ cations and chemical functional groups, such as –OH, –CONH2, –NH2 or –C=O based on the semi-IPN structure reactor templates. The size of the majority of AgNPs ranges from 12 to 25 nm, depending on the three-network templates, the presence of functional groups as well as feed ratios of N-vinylpyrrolidone, acrylamide, and chitosan. Thermogravimetric analysis (TGA) provides the stability of the resulting nanocomposite hydrogels. The nanocomposite hydrogels demonstrate reduced swelling in comparison with the P(AAm-co-NVP)/CS ones. The kinetics modeling confirms that transport mechanism of the samples follows anomalous diffusion mode, and the kinetic parameters vary with the component ratios, and the maximal theoretical water volume S∞ is well in agreement with the experimental values.
Co-reporter:Yan-Ling Luo, Qing-Bo Wei, Feng Xu, Ya-Shao Chen, Li-Hua Fan, Chang-Hu Zhang
Materials Chemistry and Physics 2009 Volume 118(2–3) pp:329-336
Publication Date(Web):15 December 2009
DOI:10.1016/j.matchemphys.2009.07.063
A series of poly(N,N-dimethylacrylamide)-g-poly(vinyl alcohol) (PDMAA-g-PVA) graft hydrogel networks were designed and prepared via a free radical polymerization route initiated by a PVA-(NH4)2Ce(NO3)6 redox reaction. Silver nanoparticles with high stability and good distribution behavior have been self-assembled by using these hydrogel networks as a nanoreactor and in situ reducing system. Meanwhile the PDMAA or PVA chains can efficiently act as stabilizing agents for the Ag nanoparticles in that Ag+ would form complex via oxygen atom and nitrogen atom, and form weak coordination bonds, thus astricting Ag+. The structure of the PDMAA-g-PVA/Ag was characterized by a Fourier transform infrared spectroscope (FTIR). The morphologies of pure PDMAA-g-PVA hydrogels and PDMAA-g-PVA/Ag nanocomposite ones were observed by a scanning electron microscopy (SEM) and transmission electron microscope (TEM). TEM micrographs revealed the presence of nearly spherical and well-separated Ag nanoparticles with diameters ranging from 10 to 20 nm, depending on their reduction routes. XRD results showed all relevant Bragg's reflection for crystal structure of Ag nanoparticles. UV–vis studies apparently showed the characteristic surface plasmon band at 410–440 nm for the existence of Ag nanoparticles within the hydrogel matrix. The swelling kinetics demonstrated that the transport mechanism belongs to non-Fickian mode for the PDMAA-g-PVA hydrogels and PDMAA-g-PVA/Ag nanocomposite ones. With increasing the DMAA proportion, the r0 and S∞ are enhanced for each system. The assembly of Ag nanoparticles and the swelling behavior may be controlled and modulated by means of the compositional ratios of PVA to DMAA and reduction systems.
Co-reporter:Yan-Ling Luo;Qing-Bo Wei;Ya-Shao Chen
Journal of Materials Science: Materials in Electronics 2009 Volume 20( Issue 8) pp:761-770
Publication Date(Web):2009 August
DOI:10.1007/s10854-008-9799-6
Novel electroconductive nanocomposites were prepared by an in situ polymerization avenue based on poly(styrene-alt-maleic anhydride) (P(St-alt-MA)), multi-walled carbon nanotubes (MWCNT) or hydroxyl-functionalized MWCNT (MWCNT–OH). Vapor sensing films with intensive response to polar solvent vapors were assembled through an covalent or non-covalent interaction between MWCNT or MWCNT–OH and P(St-alt-MA), as demonstrated by a Raman, infrared spectroscopy, scanning and transmission electron microscopes. The films gave an expeditious response, favorable reversibility and reproducibility, which were predominately controlled by an expansion effect and an interaction among carbon nanotubes, copolymers and solvent molecules.
Co-reporter:Li-Hua Fan;Ya-Shao Chen;Chang-Hu Zhang
Journal of Nanoparticle Research 2009 Volume 11( Issue 2) pp:449-458
Publication Date(Web):2009 February
DOI:10.1007/s11051-008-9556-z
A magnetic core–shell-layered polymer microsphere (MPS) was successfully synthesized by a dispersion polymerization route, where the modified Fe3O4 nanoparticles (MFN) were used as a core, while poly(maleic anhydride-co-methacrylic acid) P(MAH-co-MAA) as a shell was covered on the surface of the Fe3O4 nanoparticles. Environmental scanning electron microscope (ESME) and transmission electron microscope (TEM) measurements indicate that the magnetic P(MAH-co-MAA)/Fe3O4 composite microspheres assume sphericity and have a novel core–shell-layered structure. The crystal particle sizes of the unimproved Fe3O4 and the MFN samples vary from 8 to 16 nm in diameter, and the average size is about 10.6 nm in diameter. The core–shell magnetic composite microspheres can be adjusted by changing the stirring speed. Since multiple Fe3O4 cores were coated with a proper percentage of P(MAH-co-MAA) copolymers, and therefore lower density was acquired for the MPS, which improved sedimentation and dispersion behavior. The saturated magnetization of pure Fe3O4 nanoparticles reaches 48.1 emu g−1 and the value for composite nanoparticles was as high as 173.5 emu g−1. The nanoparticles show strong superparamagnetic characteristics and can be expected to be used as a candidate for magnetism-controlled drug release.
Co-reporter:Qing-Bo Wei, Yan-Ling Luo, Chang-Hu Zhang, Li-Hua Fan, Ya-Shao Chen
Sensors and Actuators B: Chemical 2008 Volume 134(Issue 1) pp:49-56
Publication Date(Web):28 August 2008
DOI:10.1016/j.snb.2008.04.008
A vapor-sensitive electroconductive film was designed and assembled by inserting Cu2+ particles into a polyacrylamide grafted poly(vinyl alcohol) (PAM-g-PVA) in virtue of a complexation between Cu2+ and PVA even PAM, as well as the establishment of inter- and intramolecular attractions between polymer matrices, which were in turn reduced into Cu nanoparticles by sodium hypophosphite as a reducing agent. The PAM-g-PVA graft copolymer was prepared via a simple free radical polymerization reaction initiated by a redox reaction. The resistance responsiveness of the film samples to various organic vapor surroundings was investigated. The responsive magnitude, response time and recovery properties depend on the molecular weight of the graft polymer or the PAM chain length and initial resistances of the film samples or Cu particle contents upon exposed to ether and petroleum ether vapor, etc. The structure and morphologies of the PAM-g-PVA/Cu were characterized by a Fourier transform infrared spectroscope and a transmission electron microscope. The response mechanism of the PAM-g-PVA/Cu films to solvent vapors was accounted for by a swelling theory and an interaction between solvent vapor molecules and nanocomposites as well as the type and strength of interaction that each solvent vapor exhibits on the material.
Co-reporter:Yanling Luo, Chao Wang, Zhanqing Li
Synthetic Metals 2007 Volume 157(8–9) pp:390-400
Publication Date(Web):May 2007
DOI:10.1016/j.synthmet.2007.04.009
A polyurethane inserted multi-wall carbon nanotube (MWCNT) composite conductive film was prepared by in situ dispersed polymerization reaction using hydroxyl-terminated poly(butadiene-acrylonitrile) liquid rubber as a linear diol, toluene diisocynate as a curative, ethylene glycol or glycerine or triethanolamine as a chain-extending agent and MWCNT as a conducive filler. The effect of various curing temperatures and chain-extending agents on vapor-induced electrical responsiveness of the conductive films was investigated. The structural characterization of the cured film was conducted by Fourier transformation infrared spectrophotometer (FTIR), differential scanning calorimeter (DSC), polarization microscope (POM) and wide angle X-ray diffraction (WAXD). The experimental results showed that the conductive composite film obtained in the present work exhibited a microphase separation resulting from the soft-hard segment domains, and possessed some crystalline behavior from the hard segment. The response intensity was enhanced with the curing temperature increased, while the reversibility could be improved at a relatively low curing temperature. The responsivity of the film produced by a linear difunctional group chain-extending agent was lower than that prepared by trifunctional group curatives, and the reversibility was vice versa. The experimental phenomena were explained from the viewpoint of the microphase separation, crystalline behavior, the structural characteristics of the soft-hard segment, and the electronic properties of multi-wall carbon nanotubes as well as a weak electrostatic or noncovalent interaction between polymer or analyte molecules and MWCNTs.
Co-reporter:Yanling Luo, Zhanqing Li, Wenxiang Lan
Materials Science and Engineering: B 2007 Volume 139(Issue 1) pp:105-113
Publication Date(Web):25 April 2007
DOI:10.1016/j.mseb.2007.01.041
A novel polymer based sensitive film was prepared from thermosetting epoxy resins (EP) filled with carbon blacks. The curing reaction of amine curing agents with epoxy resins and the response of the curing resultants to solvent vapors were dealt with. The influence of the types and content of carbon blacks and curing agents, and curing temperatures and time on curing reactions and response selectivity of the conductive films were investigated. The structural characterization was conducted on a Fourier transform infrared spectrophotometer (FTIR). The results indicated that the conductive films showed high response selectivity to polar solvent vapors, especially to chloroform vapor, while no response was observed in non-polar solvent vapors. The responsivity of the film increased with the decreased carbon black contents. The film filled with acetylene carbon black gave an optimal response, with responsivity of about 700 times. The response performances were improved with the amount of curing agents increased, and an optimal response appeared at the amount of the curing agent of 8%. The film's responsivity was remarkably enhanced, the reversibility property, however, rapidly declined in the order of diethyleneltriamine < triethylenetetramine < ethylenediamine. The curing reaction tended to complete with the curing temperature elevated and the curing time prolonged. But the response performance dropped because of over cross-linking as the temperature was too high or the time was too long.
Co-reporter:Yuan Wang, Yan-Ling Luo, Feng Xu, Ya-Shao Chen, Wei Tang
Journal of Industrial and Engineering Chemistry (25 April 2017) Volume 48() pp:66-78
Publication Date(Web):25 April 2017
DOI:10.1016/j.jiec.2016.12.021
Ferrocene-containing amphiphilic block copolymers, poly(2-acryloyloxyethyl ferrocenecarboxylate)-block-poly(2-(dimethylamino) ethyl methacrylate) (PAEFc-b-PDMAEMA), were synthesized via sequential ATRP, and self-assembled into globular nanoscaled micelle aggregates. The copolymer micelles exhibited reversible redox on-off switch feature, which was mediated by using H2O2, KMnO4, NaClO and FeCl3 as a model of oxidants and ascorbic acid as a model of reductants. The micelle nanoparticles were used to load and deliver anticancer drug, 10-hydroxycamptothecine, finding that the encapsulated drug was rapidly delivered by selectively responding to redox environments in cancer cells. MTT assays were performed to uncover cytotoxicity of the developed copolymer micelles and potentiality used for cancer therapy.Download high-res image (150KB)Download full-size image
Co-reporter:Yan-Ling Luo, Xue-Yin Zhang, Yuan Wang, Fang-Jie Han, Feng Xu and Ya-Shao Chen
Journal of Materials Chemistry A 2017 - vol. 5(Issue 17) pp:NaN3121-3121
Publication Date(Web):2017/03/22
DOI:10.1039/C7TB00073A
pH-Sensitive H-type multiblock copolymers, namely, poly(methacrylic acid)2-block-epoxidized hydroxyl-terminated polybutadiene-block-poly(methacrylic acid)2 (PMAA2-b-epoHTPB-b-PMAA2), were synthesized by atom-transfer radical polymerization and subsequent in situ epoxidation by peracetic acid and characterized by 1H NMR, FT-IR and SEC techniques. The impact of epoxidation on the physicochemical and biomedical properties of copolymer self-assembly micelle nanoparticles was investigated by fluorescence spectrometry, DLS, TEM and an MTT assay. The experimental results indicated that epoxidation resulted in the formation of more stable copolymer micelle nanoparticles with a lower critical micelle concentration, smaller micelle size, and higher loading capacity and encapsulation efficiency of drugs than those without epoxidation. In particular, epoxidized copolymer micelle nanoparticles exhibited reasonable pH sensitivity at a pH of 5.3–5.6. The hydrophobic anticancer drug paclitaxel (PTX) displayed faster release rates from epoxidized nanomicelles than from unepoxidized nanomicelles in a PBS solution of a pH of 4.8–6.6, whereas in PBS of a pH of 7.4 smaller amounts of PTX were released from epoxidized nanomicelles than from unepoxidized nanomicelles. Epoxidized copolymer nanomicelles were reasonably biodegradable after the drug was released, and their degradation rate was faster than that of their unepoxidized counterparts. An MTT assay was performed to determine the biocompatibility of epoxidized copolymer micelle nanoparticles and the anticancer activities of PTX-loaded nanomicelles, which were important for applications in the therapy of cancers as a controlled-release drug carrier.
