Characterization and enzymatic degradation of PEG‐cross‐linked chitosan hydrogel films

Abstract

In our previous study (Kiuch et al., J Appl Polym Sci 2008, 107, 3823), poly(ethylene glycol) (PEG) cross-linked chitosan hydrogel films with various PEG to chitosan ratio and PEG molecular weight have been successfully prepared and their thermal, mechanical and swelling properties at acidic pH were studied. These films are potential biodegradable polymeric materials, because their constituents, that is, chitosan and PEG, are well known as biodegradable polymers. In this study, glass transition temperature (T g ), contact angle, swelling behavior at physiological conditions and in vitro enzymatic degradation behavior were investigated for the PEG-crosslinked chitosan hydrogel films. These properties of chitosan hydrogel were found to change significantly upon introducing the PEG-cross-links. According to differential scanning calorimeter analysis, the T g value increased with the PEG content in the hydrogel films, indicating the densification of the film by PEG-crosslinking. The contact angle was decreased with increasing the number of crosslinks, reflecting that introduction of the cross-linked structure induced the reduction of chitosan ordered structure. The swelling behavior depended on the PEG to chitosan ratio and the cross-linked structure. The water content was changed with the number of PEG-crosslinks. The rate of lysozyme-catalyzed degradation was also influenced by the introduction of PEG-cross-linked structure. The surface morphology of the film was observed by the scanning electron microscopy. It was confirmed that the PEG-crosslinked chitosan hydrogel film was degraded by lysozyme from its surface area.

Photo, thermal, and ultrasonic degradation of EGDMA‐crosslinked poly(acrylic acid‐co‐sodium acrylate‐co‐acrylamide) superabsorbents

“…The synthesis of various SAPs based on both natural and synthetic monomers is well established. Although there are many studies of enzymatic degradation of SAPs based on natural sources,26, 27 there is not much information available about the degradation of the SAPs based on synthetic monomers such as AA and AM. Li and Cui28 have reported ultraviolet‐induced degradation of AA‐ and AM‐based superabsorbents by monitoring the weight at the end of the degradation.…”

Synthesis, characterization, and enzymatic degradation of chitosan/PEG hydrogel films

“…In general, polysaccharides have a strong affinity for water and can be easily hydrated in the solid state. 22 For this reason, the broad peak was also observed for the hydrogel films. Whereas, CPT film samples also showed a sharp endothermic peak centered at the temperatures between 40 and 50°C.…”

“…But the degradation of CS film was not so clearly, because its degradation was very slow. 22 The in vitro degradation behavior of CS has been usually investigated using HEW lysozyme, 25–27 because HEW lysozyme as well as human lysozyme cleavages the b(1–4)‐linked GlcNAc and GlcN subunits of CS. 9…”

Photosensitive chitosan to control cell attachment

“…PEG immobilization on the deprotected surfaces caused the bigger change in advancing water contact angle. It is 52.3 ± 7.9°for PEG-NVOC-CS, which is acceptable [42]. But the relatively high water contact angle for PEG-covered surface suggests that the coverage of PEG on chitosan is limited.…”