Cu2+ Coordination-Triggered Silk Fibroin Aggregation Structures for Enhanced Robustness and Biofunctionality

Abstract

Silk-based materials are regarded as promising biomaterials. However, the simultaneous improvement of robustness and bioactivity remains a challenge for regenerated silk fibroin (SF). Herein, copper ion-coordinated SF (Cu@SF) films were fabricated via a one-step strategy, where Cu2+ coordination triggered the modulation of the SF aggregation structure. Cu2+ effectively modulates the aggregation structure of SF, which preserves intrinsic β-sheet nanocrystals (∼ 39%) and reinforces amorphous domains through coordination bonding. Benefiting from the reconstruction of amorphous domains triggered by Cu2+ coordination, the Cu@SF films exhibit enhanced toughness (25.62 MJ m−3). Also, the retained nanocrystal-confined amorphous network structure of Cu@SF results in a labyrinth effect when coated on magnesium, realizing anticorrosion robustness. Further, the dynamic coordination regulates Cu2+ release behavior, endowing the Cu@SF with efficient antibacterial activity (over 98% for E. coli and S. aureus) and favorable osteogenic bioactivity. This work provides a facile strategy for the rational design of robust and multifunctional silk-based biomaterials.