While collagen can self-assemble, a process known as fibrillation, at physiological pH, temperature, and salt concentration to form a hydrogel, such physically assembled collagen hydrogels are too soft for surgical manipulations, and results in excessive swelling, too quick dissolution, and is prone to rapid enzymatic degradation. One potential solution to this problem would be to chemically crosslink the collagen molecules to form a hydrogel since permanent covalent bonds are more stable than physical interactions and should prevent excessive swelling and too rapid dissolution in vivo. Hence, we and others have developed chemically crosslinked collagen hydrogels employing the pendant amines and carboxylic acids from the side-chains of collagen. However, such crosslinking chemistries developed to date are toxic. If such hydrogels need to be injected in vivo, the crosslinking reaction needs to be quenched prior to injection. This defeats the purpose of chemical crosslinking as often incomplete crosslinking leads to a very soft hydrogel. Alternatively, injection of the hydrogel after complete crosslinking results in a non- cohesive crushed gel. In either case, cell-delivery using such hydrogels is highly challenging due to the toxic nature of the crosslinking chemistry.