Injectable collagen-chitosan hydrogel using ultrasonic pretreated ovine tendon collagen

Abstract

Normally discarded as waste, ovine tendon collagen has great potential for use as an injectable hydrogel. Typical collagen used for biomedical applications is derived from epidermal tissue. Compared to the epidermal collagen, tendon collagen consists of collagen fibrils with large diameters. This limits the conjugation of phenolic hydroxyl (Ph) groups to tendon collagen for the synthesis of an injectable hydrogel. In this study, pretreatment process by ultrasonication was used to prevent the aggregation of ovine tendon collagen fibril, thus reducing fibril diameters and increasing the surface area for effective conjugation of Ph groups to collagen-chitosan (Col-Chit) composite. In situ gelation of Col-Chit-Ph composite was achieved via peroxidase-catalyzed crosslinking reaction at physiological conditions. The collagen to chitosan (Col: Chit) ratio was found to significantly influence the physical, mechanical and biological properties of hydrogels. The higher composition of chitosan in the hydrogel with 1:1 Col: Chit ratio resulted in the shortest gelation time (< 1 minute) and higher mechanical strength (> 0.35 N) in all conditions. However, the poor cell growth rate of hydrogel at this Col: Chit ratio might limit its further use. The hydrogel with 3:2 Col: Chit ratio was mechanically stable and has the highest cell growth rate among others with difference of cell growth rate of about 94 % compared to the 1:1 ratio. Taking into account these biological features, hydrogel with 3:2 Col: Chit ratio is suggested for potential use in biomedical applications. This study shows the feasibility of using ultrasonic pretreatment method for collagen with large fibril diameter.