Mussel-inspired adhesive protein-based electrospun nanofibers reinforced by Fe(III)-DOPA complexation

Marine mussels utilize multiple bidentate complexes formed by Fe((III)) and DOPA in a mussel adhesive protein (fp-1) to reinforce tough and elastic byssal fibers as a specialized underwater adhesive aid. In this study, mussel- inspired electrospun nanofibers were fabricated using a recombinant mussel adhesive protein (rfp-1), Fe((III))- DOPA complexes, and polycaprolactone. The mechanical properties of the fabricated nanofibers were reinforced by the Fe((III))-DOPA complex found in fp-1, which is a key component of the naturally occurring high-performance mussel fiber coating. Experimental results show that the stoichiometry of Fe((III))-DOPA complexes in the nanofibers could be controlled by buffer pH conditions and the stiffness of the nanofiber mat increased linearly with the concentration of the Fe((III))-DOPA complexes, as monitored by resonance Raman spectroscopy. This suggests the potential of Fe((III))-DOPA complexation as an effective strategy for modulating the mechanical properties of nanofibrous biomedical materials by using pH variations.