Injectable chitosan/dextran-polylactide/glycerophosphate hydrogels and their biodegradation

Abstract

Dextran-polylactide (Dex-PLA) copolymers were synthesized and the selected Dex-PLA with water-soluble characteristics was used together with chitosan and glycerophosphate (GP) to produce injectable chitosan/Dex-PLA/GP hydrogels. Some chitosan/Dex-PLA/GP solutions with designated compositions were able to form into hydrogel in a temperature range between around 32 and 35 °C, and their pH values were found to alter between 7.0 and 7.2. Elastic modulus of the optimal chitosan/Dex-PLA/GP gel could reach about 1.0 kPa or higher, and meanwhile, it was much higher than their viscous modulus, revealing that these chitosan/Dex-PLA/GP gels behave like mechanically strong ones. Compression measurements indicated that the certain chitosan/Dex-PLA/GP gels had around 8-fold modulus and strength higher than the chitosan/GP gel, confirming that greatly enhanced compressive properties for chitosan/Dex-PLA/GP gels have been achieved. After 8-week subcutaneous degradation in rats, some chitosan/Dex-PLA/GP gels showed significantly extended degradation endurance compared to the chitosan/GP gel, and the PLA content in the chitosan/Dex-PLA/GP gels was able to regulate the degradation rate of the gels in a controllable manner. These results suggest that the presently developed chitosan/Dex-PLA/GP gels have promising potential for injectable gelling applications where the gel with mechanically strong features and degradation tolerance is needed.