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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.

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. Source

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

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. Source

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

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. Source

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

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. Source

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

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. Source

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