Development of bullfrog collagen-based hydrogels as novel cellular encapsulants

Abstract

Towards a zero-waste approach and sustainability in waste management, unwanted bullfrog skin was sought after for its abundant source of collagen. Collagen hydrogels were acknowledged for their beneficial attributes in regenerative medicine or tissue engineering. Yet, native collagen was unsuitable for biomedical applications due to vulnerable characteristics. In this study, American bullfrogs (Rana catesbeianus) skin-derived collagen was subjected to methacrylation of different degrees by methacrylic anhydride (MAA) ranging from 0.1 to 3 ml/g of MAA to collagen, followed by photo-sensitive chemical cross-linking to develop methacrylated collagen (ColMA) hydrogel with good handle-ability and physicochemical stability as a cell encapsulant material. Collagen with a good preservation of the triple helical structure was successfully isolated, with ATR-FTIR analysis showing an absorbance peak intensity ratio of close to 1, and a denaturation temperature of 39.54°C. Hydrogels of different degrees of modifications were successfully fabricated and further characterized for its assessment as promising biomaterials in cell encapsulation. Our results indicated that ColMA hydrogel (1 ml/g MAA to collagen) demonstrated good modulus and long-term stability (> 21 days). In addition, crosslinked hydrogel exhibited significant improvement on the thermal stability with good cytocompatibility. Overall, modification and optimization of bullfrog skin-derived collagen was necessary to develop the most desirable cell-friendly hydrogel for encapsulation purposes.