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Ouyang C.,Institute of Polymer Chemistry | Wang Y.,Institute of Polymer Chemistry | Zhao N.,Institute of Polymer Chemistry | Liu X.,Tsinghua University | And 2 more authors.
Polymer Bulletin | Year: 2012

In this article, the pretreatment before extrusion between the PLA and the modified starch was researched. The research on the composites of PLA and the modified starch focused on improving its compatibility and mechanical properties. The pretreatment samples were characterized by solid 13C-NMR and the chemical titration of the carboxyl end (-COOH) groups in PLA. The results illuminated that the pretreatment reaction was successful and the -COOH in PLA had reacted with the -OH in modified starch. The compatibility of the composites was determined by differential scanning calorimetry and scanning electron microscopy. The results showed that pretreatment could improve the compatibility of the composites. The mechanical properties of the composites were also enhanced. This approach is identified as a reasonable method to produce commercial PLA/modified starch composites with economical feasibility. © Springer-Verlag 2011.


Wang Y.,Institute of Polymer Chemistry | Yan R.,Institute of Polymer Chemistry | Zhang J.,Institute of Polymer Chemistry | Zhang W.,Institute of Polymer Chemistry
Journal of Molecular Catalysis A: Chemical | Year: 2010

Synthesis of size-controlled Au nanoparticles for aerobic alcohol oxidation within a porous, chelating and intelligent hydrogel of poly(N-isopropylacrylamide)-co-poly[2-methacrylic acid 3-(bis-carboxymethylamino)-2-hydroxypropyl ester] (PNIPAM-co-PMACHE) is studied. The PNIPAM-co-PMACHE hydrogel is demonstrated to be a suitable scaffold, within which Au nanoparticles with size ranging from 2.6 to 6.3 nm are synthesized by reducing the Au precursor of HAuCl4 with different reducing agents. The synthesized composite of the hydrogel and the encapsulated Au nanoparticles is thermoresponsive, which can reversibly deswell/swell at the volume-phase-transition temperature (VPTT) at 27 °C. The encapsulated Au nanoparticles keep stable during the reversible deswelling/swelling of the thermoresponsive hydrogel/Au composite. The catalysis of the thermoresponsive composite is tested employing aerobic alcohol oxidation as model reaction and it is found that the catalytic activity of the thermoresponsive composite is strongly dependent on the size of the encapsulated Au nanoparticles. Besides, it is found that the thermoresponsive composite is catalytically efficient for aerobic alcohol oxidation partly since the reactant of alcohol is highly concentrated within the hydrogel matrix through the reversible deswelling and partly since the reactant of alcohol can be activated through the strong hydrogen bonding between the alcohol molecules and the poly(N-isopropylacrylamide) segment. And furthermore, the reversible deswelling/swelling of the thermoresponsive composite provides great convenience for catalyst recycling. © 2009 Elsevier B.V. All rights reserved.


Zhang S.,Institute of Polymer Chemistry | Wang J.,Institute of Polymer Chemistry | Han L.,Institute of Polymer Chemistry | Li C.,Institute of Polymer Chemistry | And 2 more authors.
Sensors and Actuators, B: Chemical | Year: 2010

Protein phosphorylation plays an important role in intracellular signaling. Defects in the phosphorylation process, which are associated with cancers and other human diseases, can be reflected by the presence of abnormally phosphorylated peptides in serum. Therefore, phosphorylated peptides are important resources for biomarker discovery. However, few studies have been reported on developing sensors for phosphorylated peptides. In this study, zinc(ii) dipicolylamine-appended gold nanoparticles were synthesized and used for the colorimetric detection of bis-phosphorylated peptides. The addition of the bis-phosphorylated peptides could induce the aggregation of the functionalized AuNPs, and thus the color change of the gold colloid, while non-phosphorylated and mono-phosphorylated controls could not induce the color change. © 2010 Elsevier B.V. All rights reserved.


Liu Y.,Institute of Polymer Chemistry | Wang W.,Institute of Polymer Chemistry | Wang J.,Institute of Polymer Chemistry | Wang Y.,Institute of Polymer Chemistry | And 4 more authors.
Colloids and Surfaces B: Biointerfaces | Year: 2010

Endothelialization is an ideal approach to improve the blood compatibility of synthetic polymers. However, cell detachment is inevitable under shear flow conditions. Therefore, the issue of blood compatibility needs to be addressed for both the bare and the endothelialized polymer. RGD-containing polymer P-GS5 was synthesized by modification of poly(d,l-lactide-co-beta-malic acid) (PLMA) with the peptide GRGDS. The compositions, molecular weights and hydrophilicities of poly(d,l-lactide) (PDLLA), PLMA, and P-GS5 were characterized by nuclear magnetic resonance (NMR), X-ray photoelectron spectroscopy (XPS), gel-permeation chromatography (GPC) and water contact angle measurements, respectively. The blood compatibilities of the bare and the endothelialized polymers were evaluated by clotting time and platelet adhesion tests. The results showed that the coagulation pathways were not influenced before and after cell culture; the bare P-GS5 attracted less platelet adhesion and induced lower pseudopodia extension compared with PDLLA and PLMA, and the platelet adhesion on P-GS5 was almost completely eliminated after cell seeding. The results suggest that P-GS5 could be a potentially useful material in vascular tissue engineering. © 2009 Elsevier B.V. All rights reserved.


Tian Z.,Institute of Polymer Chemistry | Yang C.,Institute of Polymer Chemistry | Wang W.,Institute of Polymer Chemistry | Yuan Z.,Institute of Polymer Chemistry
ACS Applied Materials and Interfaces | Year: 2014

A new approach to shield/deshield ligands for controllable tumor targeting was reported, which was based on amphiphilic self-assembly and disassembly of gold nanoparticles (Au NPs). Thanks to the excellent pH response of the system, glycyrrhetinic acid (GA) ligands can be buried inside the Au NPs' assembly at normal tissue pH (pH 7.4), while exposed when the nanostructure is disassembled at tumor extracellular pH (pHe 6.8). Hydrophobic GA molecules not only acted as ligands targeting tumor cells but also provided the major interparticle attractive force for Au NPs' assembling. An ordered assembly of Au NPs with regular shape, proper size and ultrasharp pH sensitivity (ΔpH ∼ 0.2) was achieved by fine-tuning of materials modified on Au NPs. Mechanism studies for assembly and disassembly of Au NPs indicated the possibility of a GA shield when the assembly formed, which was further demonstrated by bovine serum albumin absorption and cellular uptake. The assembly/disassembly process was reversible within extrinsic pH changes, which provides a perspective for reversible tumor targeting. © 2014 American Chemical Society.


Shu S.,Institute of Polymer Chemistry | Sun C.,Institute of Polymer Chemistry | Zhang X.,Institute of Polymer Chemistry | Wu Z.,Tianjin Medical University | And 2 more authors.
Acta Biomaterialia | Year: 2010

Biodegradable hollow capsules encapsulating protein drugs were prepared via layer-by-layer assembly of water-soluble chitosan and dextran sulfate on protein-entrapping amino-functionalized silica particles and the subsequent removal of the silica. In order to enhance the encapsulated efficiency and decrease its burst release, we designed this new system to fulfill these two goals. Bovine serum albumin (BSA), which was used as model protein, was entrapped in the nanocapsules. This system demonstrated a good capacity for the encapsulation and loading of BSA. The burst release was decreased to less than 10% in phosphate-buffered saline within 2 h. No significant conformation change was noted from the released BSA in comparison with native BSA by using circular dichroism spectroscopy. Cell viability study suggested that the nanocapsules had good biocompatibility. The drug release kinetics mechanism is Fickian diffusion. These kinds of novel composite nanocapsules may offer a promising delivery system for water-soluble proteins and peptides. © 2009 Acta Materialia Inc.


Teng D.-y.,Institute of Polymer Chemistry | Wu Z.-m.,Tianjin Medical University | Zhang X.-g.,Institute of Polymer Chemistry | Wang Y.-x.,Institute of Polymer Chemistry | And 3 more authors.
Polymer | Year: 2010

A novel injectable in situ cross-linked hydrogel has been designed via Michael type addition between thiol-modified chitosan (CS-NAC) and PEG diacrylate (PEGDA). Hydrogel was rapidly formed in situ under physiological conditions. The gelation time depended on the content of free thiols in CS-NAC, temperature, and concentration of CS-NAC and PEGDA. Thermogravimetric analysis showed the thermal stabilities of hydrogels. SEM observation results confirmed a porous 3D structure. Rheological studies showed that the cross-linking density and elasticity of hydrogel had a correlation to the content of CS-NAC and PEGDA. Swelling studies revealed that these hydrogels had a high initial swelling and were degradable under physiological conditions. And swelling was highly temperature-dependent and was directly related to the amount of cross-linking. Biological activities of the hydrogels were evaluated by in vitro cell compatibility on HDFs and A549 cells and the results indicated that the hydrogel was biocompatible. © 2009 Elsevier Ltd. All rights reserved.


Guo T.-Y.,Institute of Polymer Chemistry | Liu P.,Institute of Polymer Chemistry | Xia Y.-Q.,Institute of Polymer Chemistry | Song M.-D.,Institute of Polymer Chemistry
Journal of Applied Polymer Science | Year: 2010

The surface free-radical graft polymerization of 2-O-meth- acryloyloxyethoxyl-(2,3,4,6-tetra-O-acetyl-β-D-galactopyranosyl)-(1-4)-2,3, 6-tri-O-acetyl-β-D-glucopy-ranoside onto silica gel particles has been carried out with azobis (isobutyronitrile) as initiator. The grafting reaction conditions and the glycopolymer-grafted silica gel particles have been investigated in detail. Chromato-graphic experiments have been attempted on glycopolymer-modified silica gel particles as a stationary phase under normal phase conditions, and it was found that a certain separation effect of the quercetin and its derivant isorhamnetin was achieved. © 2010 Wiley Periodicals, Inc.


Xiong D.,Institute of Polymer Chemistry | Li Z.,Institute of Polymer Chemistry | Zou L.,Institute of Polymer Chemistry | He Z.,Institute of Polymer Chemistry | And 4 more authors.
Journal of Colloid and Interface Science | Year: 2010

Polymeric micelles with a polystyrene core, poly(acrylic acid)/poly(4-vinyl pyridine) (PAA/P4VP) complex shell and poly(ethylene glycol) & poly(N-isopropylacrylamide) (PEG & PNIPAM) mixed corona were synthesized and used as the supporter for the gold nanoparticles (GNs). It was concluded from the result of 1H NMR characterization that hydrophilic channels formed around PEG chains when PNIPAM collapsed above its lower critical solution temperature. The density of the channels in the corona can be tuned by changing the weight ratios of PEG chains to PNIPAM chains. The GNs were set in the PAA/P4VP complex layer and the catalytic activity of the GNs can be modulated by the channels. The catalytic activity increased with increasing the density of the channels in the corona. Meanwhile, the whole Au/micelle nanoparticles were stabilized by the extended PEG chains. © 2009 Elsevier Inc. All rights reserved.


Liu T.,Institute of Polymer Chemistry | Zhang W.,Institute of Polymer Chemistry | Song T.,Institute of Polymer Chemistry | Yang X.,Institute of Polymer Chemistry | Li C.,Institute of Polymer Chemistry
Polymer Chemistry | Year: 2015

Nitric oxide (NO)-releasing hollow double-layered polymer microspheres (HDPMs) with both pH- and thermo-responsive properties in aqueous media are designed and prepared by a multi-step process. Hollow double-shelled polymer microspheres with secondary amino groups are prepared by distillation precipitation copolymerization of N-isopropylacrylamide (NIPAAm) with 2-(dimethylamino)ethyl methacrylate (DMAEMA) and EGDMA in the presence of SiO2/P(2-(ethyl(boc)amino)ethyl methacrylate (bocAmEMA)-co-EGDMA) core-shell microspheres as seeds to obtain SiO2/P(bocAmEMA-co-EGDMA)/P(EGDMA-co-DMAEMA-co-NIPAAm) tri-layered microspheres with subsequent removal of the silica core by hydrogen fluoride aqueous solution and deprotection of secondary amino groups with CF3CO2H. Hollow polymer microspheres with N-diazeniumdiolated NO donors are prepared by the reaction between secondary amino groups of hollow P(AmEMA-co-EGDMA)/P(EGDMA-co-DMAEMA-co-NIPAAm) microspheres and high pressure of NO (5.0 atm) under basic conditions (CH3ONa). The resulting microspheres are systematically characterized by TEM, FT-IR, TGA, elemental analysis and dynamic laser scattering (DLS). The final N-diazeniumdiolated hollow double-shelled microspheres show a controlled NO release behavior dependent on pH and temperature in the environments. This journal is © The Royal Society of Chemistry 2015.

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