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:Yan-Ling Luo;Xue-Yin Zhang;Yuan Wang;Fang-Jie Han;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;Yan-Ling Luo
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: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:Tangqian Jiao, Jingxuan Tu, Gaoqiang Li, Feng Xu
Journal of Molecular Catalysis A: Chemical 2016 Volume 416() pp:56-62
Publication Date(Web):15 May 2016
DOI:10.1016/j.molcata.2016.02.004
•Cu-camphor Schiff base complexes were firstly investigated as catalysts in asymmetric Henry reaction.•The diastereoisomeric Schiff bases 5a and 5a' were successfully isolated and gave completely converse absolute configuration of catalyzed products when it used in the Henry reaction as ligand, respectively.•The chiral camphor Schiff base 5a, together with CuCl, showed high efficiency in catalyzed asymmetric Henry reactions between various aldehydes and nitromethane.Five novel chiral camphor Schiff bases have been synthesized and utilized as ligands in asymmetric Henry reaction between nitromethane and aldehydes. The diastereoisomeric Schiff bases 5a and 5a' were separated successfully and gave completely different absolute configurations in the reaction. The reactions were carried out with CuCl-Schiff base 5a complex under mild condition with good yields and enantioselectivities. This is the first time that camphor-derivated Schiff bases were used as ligands in asymmetric Henry reaction.
Co-reporter:Yan-Ling Luo;Rui-Xue Bai;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;Jun Zhang;Fang-Jie Han;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, Yanpeng Liu, Jingxuan Tu, Chao Lei, Gaoqiang Li
Tetrahedron: Asymmetry 2015 Volume 26(Issue 17) pp:891-896
Publication Date(Web):15 September 2015
DOI:10.1016/j.tetasy.2015.07.004
Five novel chiral camphor Schiff bases were designed. Schiff base L3 showed high efficiency in Fe(III)-catalyzed asymmetric hydrophosphonylations of aldehydes, giving the corresponding products in high yields (up to 91%) along with moderate to good enantioselectivities (up to 82%).(1S,2R,4R)-1-(2-Hydroxybenzylideneamino)-7,7-dimethyl-bicyclo[2.2.1]heptan-2-olC16H21NO2[α]D22 = −110.8 (c 1.0, CHCl3)Absolute configuration: (1S,2R,4R)(1S,2R,4R)-1-(2-Hydroxy-3-methoxybenzylideneamino)-7,7-dimethylbicyclo[2.2.1]heptan-2-olC17H23NO3[α]D22 = −157.2 (c 1.0, CHCl3)Absolute configuration: (1S,2R,4R)(1S,2R,4R)-1-(2-Hydroxy-3-methylbenzylideneamino)-7,7-dimethylbicyclo[2.2.1]heptan-2-olC17H23NO2[α]D22 = −56.1 (c 1.0, CHCl3)Absolute configuration: (1S,2R,4R)(1S,2R,4R)-1-((E)-3,5-Di-tert-butyl-2-hydroxybenzylidene-amino)-7,7-dimethylbicyclo[2.2.1]heptan-2-olC24H37NO2[α]D22 = −51.4 (c 1.0, CHCl3)Absolute configuration: (1S,2R,4R)4-((E)-((1S,2R,4R)-2-Hydroxy-7,7-dimethylbicyclo[2.2.1]-heptan-1-ylimino)methyl)benzene-1,3-diolC16H21NO3[α]D22 = −175.1 (c 1.0, CHCl3)Absolute configuration: (1S,2R,4R)
Co-reporter:Feng Xu, Lei Yan, Chao Lei, Hao Zhao, Gaoqiang Li
Tetrahedron: Asymmetry 2015 Volume 26(Issue 7) pp:338-343
Publication Date(Web):15 April 2015
DOI:10.1016/j.tetasy.2015.03.003
Four chiral amino alcohols with a sulfur substituent were synthesized from d-(+)-camphor and utilized as ligands in Cu(I)-catalyzed asymmetric Henry reactions between nitromethane and various aldehydes. The reactions were carried out under mild conditions with excellent enantioselectivities and good yields without the exclusion of air or moisture. The highest enantioselectivity was observed (up to 96% ee) with ligand 3c in CH3NO2 at 0 °C.(1R,2S,3R,4S)-1,7,7,Trimethyl-3-(2-(4-tolythio)benzylamino)bicycle-[2,2,1]heptan-2-olC24H31NOSAbsolute configuration: (1R,2S,3R,4S)[α]D22 = +35.1 (c 0.77, CHCl3)Source of chirality: (1R,2S,3R,4S)-3-Amino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol(1R,2S,3R,4S)-1,7,7,Trimethyl-3-((thiophen-2-yl)methylamino)bicycle[2,2,1]heptan-2-olC15H23NOSAbsolute configuration: (1R,2S,3R,4S)[α]D22 = +36.4 (c 0.67, CHCl3)Source of chirality: (1R,2S,3R,4S)-3-Amino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol(1R,2S,3R,4S)-1,7,7,Trimethyl-3-((5-Methylthiophen-2-yl)-methylamino)bicycle[2,2,1]heptan-2-olC16H25NOSAbsolute configuration: (1R,2S,3R,4S)[α]D22 = +38.6 (c 0.83, CHCl3)Source of chirality: (1R,2S,3R,4S)-3-Amino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol(1R,2S,3R,4S)-1,7,7,Trimethyl-3-(Furan-2-ylamino)bicycle[2,2,1]-heptan-2-olC15H23NO2Absolute configuration: (1R,2S,3R,4S)[α]D22 = +44.3 (c 0.40, CHCl3)Source of chirality: (1R,2S,3R,4S)-3-Amino-1,7,7-trimethylbicyclo[2.2.1]heptan-2-ol
Co-reporter:Feng Xu;Chao Lei;Lei Yan;Jingxuan Tu ;Gaoqiang Li
Chirality 2015 Volume 27( Issue 10) pp:761-765
Publication Date(Web):
DOI:10.1002/chir.22498
Abstract
Four novel chiral amino alcohols were synthesized from D-(+)-camphor and utilized as ligands in a Cu(I)-catalyzed asymmetric Henry reaction. The reactions were carried out under mild conditions with excellent enantioselectivities and moderate yields without the exclusion of air or moisture. The highest enantioselectivity was observed up to 94% enantiomeric excess (ee) with ligand L1 in toluene at room temperature. Chirality 27:761–765, 2015. © 2015 Wiley Periodicals, Inc.
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, 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:Xiao-Li Yang;Yan-Ling Luo;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;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;Rui-Juan Huang;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: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:Yan-Ling Luo;Xiao-Li Yang;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:Feng Xu;Nige Wang;Youping Tian ;Gaoqiang Li
Journal of Heterocyclic Chemistry 2013 Volume 50( Issue 3) pp:668-675
Publication Date(Web):
DOI:10.1002/jhet.1818
Benzotriazole is an efficient, readily available, and simple catalyst for the synthesis of 2,4,5-trisubstituted imidazoles in high yields from 1,2-diketones and aldehydes in the presence of NH4OAc via multi-components reaction. The significant features of this one-pot procedure are very simple operation, easy work-up and purification of products.
Co-reporter:Feng Xu;Shu-Zhen Zheng ;Yan-Ling Luo
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:Yan-Ling Luo;Wei Yu
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:YongMei Chen;Kun Dong;ZhenQi Liu
Science China Technological Sciences 2012 Volume 55( Issue 8) pp:2241-2254
Publication Date(Web):2012 August
DOI:10.1007/s11431-012-4857-y
With high water content (∼90 wt%) and significantly improved mechanical strength (∼MPa), double network (DN) hydrogels have emerged as promising biomaterials with widespread applications in biomedicine. In recent years, DN hydrogels with extremely high mechanical strength have achieved great advance, and scientists have designed a series of natural and biomimetic DN hydrogels with novel functions including low friction, low wear, mechanical anisotropy and cell compatibility. These advances have also led to new design of biocompatible DN hydrogels for regeneration of tissues such as cartilage. In this paper, we reviewed the strategies of designing high-strength DN hydrogel and analyzed the factors that affect DN hydrogel properties. We also discussed the challenges and future development of the DN hydrogel in view of its potential as biomaterials for their biomedical applications.
Co-reporter:Yan-Ling Luo;Yan Miao
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:Feng Xu;Ting-Ting Yan;Yan-Ling Luo
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, 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, 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:Yan-Ling Luo;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:Yanling Luo;Changhu Zhang;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, 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: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.
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