Tuning the swelling behavior and primary amino content of gelatin-DOPA bioconjugate films crosslinked with either genipin or GPTMS

The 3,4-dihydroxyphenyl- l -alanine (DOPA) is responsible for the outstanding adhesiveness of foot proteins secreted by mussels. Thanks to DOPA these invertebrates could adhere to various surfaces under wet conditions. Inspired by this natural phenomenon, the DOPA could be bioconjugate with a natural polymer to approach the properties of mussel foot proteins. These bioconjugates can be used to create patches and injectable bioadhesives to stop bleeding in medical emergencies. In this work, the DOPA was bioconjugate with gelatin employing N -hydroxysuccinimide (NHS) and 1-ethyl-3-(3-dimethylaminopropyl) carbodiimide hydrocloride (EDC) coupling agents. Up to 67% of bioconjugation degree was achieved when the EDC:NHS ratio was set to 1:1. However since the gelatin is highly soluble in water, the bioconjugate is also soluble. To address this, the GD bioconjugate was manufactured into films and crosslinked with either genipin (GP) or (3-glycidyloxypropyl)trimethoxysilane (GPTMS). Fourier transform infrared spectroscopy showed the C–N and Si–O–Si bonds formed after the modification with GP and GPTMS, respectively. After crosslinking, the GD films modified with GP retained around half of the amino groups, in contrast to those modified with GPTMS which severely lost this functional group. the swelling degree was also higher in GD films treated with GP compared to GPTMS. These findings suggest that the GD films crosslinked with GP have potential use as a tissue adhesive.