Fig. 2.

Physical cross-linking mechanisms of collagen hydrogels. 1: Showcases the parameters that affect collagen fibrillogenesis namely a) pH – collagen fibers become thinner and denser as pH increases b) collagen concentration – collagen fibers become denser as concentration increases and c) orientation – fibers can be organized directionally through magnetic and electric fields or a specialized mold. 2: Outlines the further physical cross-linking mechanisms used when designing collagen hydrogels. a) Dehydrothermal treatment (DHT) takes advantage of heat under vacuum to create amide bonds in collagen hydrogels and b) UV irradiation that binds histidines with hydroxyl groups.