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Wound dressings of chitosan are biocompatible, biodegradable, antibacterial and hemostatic biomaterials. However, applications for chitosan are limited due to its poor mechanical properties. Here, we conducted an in vivo mouse angiogenesis study on reinforced poly(ethylene glycol) (PEG)-chitosan (RPC) hydrogels. RPC hydrogels were formed by cross-linking chitosan with PEGs of different molecular weights at various PEG to chitosan ratios in our previous paper. These dressings can keep the wound moist, had good gas exchange capacity, and was capable of absorbing or removing the wound exudate. We examined the ability of these RPC hydrogels and neat chitosan to heal small cuts and full-thickness skin defects on the backs of male Balb/c mice. Histological examination revealed that chitosan suppressed the infiltration of inflammatory cells and accelerated fibroblast proliferation, while PEG enhanced epithelial migration. The RPC hydrogels promoted wound healing in the small cuts and full layer wounds. The optimal RPC hydrogel had a swelling ratio of 100% and a water vapor transmission rate (WVTR) of about 2000 g/m(2)/day. In addition, they possess good mechanical property and appropriate degradation rates. Thus, the optimal RPC hydrogel formulation functioned effectively as a wound dressing and promoted wound healing., (Copyright © 2013 Elsevier B.V. All rights reserved.)

ABSTRACT Chitosan has received extensive attention as a biomedical material; however, the poor solubility of chitosan is the major limiting factor in its utilization. In this study, chitosan-based biomaterials with improved aqueous solubility were synthesized. Two molecular weights (750 Da and 2000 Da) of methoxypoly(ethylene glycol) (mPEG) were grafted onto chitosan (mPEG-g-chitosan) to form a ∼100-μm-thick plastic film as a wound dressing. The chemical structures of the mPEG-g-chitosan copolymers were confirmed using Fourier transform infrared spectroscopy (FTIR), and the thermal properties were characterized using thermogravimetry analysis (TGA). Their microstructures were observed using scanning electron microscopy (SEM). The other properties were analyzed via the swelling ratio, tensile strength, elongation, and water vapor transmission rate (WVTR). Biocompatibility evaluations through biodegradability, cytotoxicity, and antimicrobial effect studies were also performed. The obtained mPEG-g-chitosan copolymers were soluble in slightly acidic aqueous solutions (pH∼6.5) at a concentration of 10 wt %. The optimal mPEG-g-chitosan hydrogels had swelling ratios greater than 100% and WVTRs greater than 2000 g/m2/day. Their performance against Staphylococcus aureus will be subjected to further improvements with respect to medical applications. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 42340. [ABSTRACT FROM AUTHOR]

PEG is used to reinforce chitosan-based hydrogels through the formation of ester and amide linkages. The reinforced PEG/chitosan (RPC) hydrogels exhibit significant enhancements in tensile modulus and elongation compared with neat chitosan. Other properties are thoroughly investigated and indicate that the physicochemical and in vitro degradation properties of the RPC hydrogels depend on the amount and molecular weight of the PEG. The RPC hydrogels can control evaporative water loss at a suitable rate to maintain a moist environment. In terms of in vitro biological properties, 3T3 fibroblasts show good viability with the RPC hydrogels, which indicates that the RPC hydrogels may be used as wound dressing materials. [ABSTRACT FROM AUTHOR]