A genipin crosslinked silk fibroin monolith by compression molding with recovering mechanical properties in physiological conditions

Abstract

Fibroin monoliths, produced by compression molding starting from the protein powder, are known to achieve an impressive mechanical strength when tested in dry conditions. However, in the presence of water, the loss of structural integrity and mechanical performances is striking. Considering the bone scaffold applications for which this material is intended, this remarkable weakening after implantation strongly limits its usage to non-structural purposes. Here, we propose an approach that allows the recovery of mechanical properties and the retention of the shape in physiological conditions, due to a progressive chemical crosslinking triggered by genipin and humidity. Crosslinking does not hinder cell adhesion and proliferation, as suggested by a preliminary biological test, nor does it limit the machinability of the material, as demonstrated by producing complex-shaped objects through laser cutting. Overall, genipin-crosslinked solid fibroin is a reliable material that may be suitable for structural applications in physiological conditions.