Epigallocatechin gallate-mediated interaction modulates the gelation properties and antibacterial spectrum of rigid amyloid lysozyme fibril-chitosan hydrogels

This study systematically investigated the molecular interactions underlying the construction of an epigallocatechin gallate (EGCG)-mediated lysozyme amyloid fibrils (LAFs)-chitosan hydrogel. The multiple hydroxyl and aromatic ring structures of EGCG were found to interact with LAFs, resulting in a redistribution of the surface charge of the complex. Meanwhile, the exposure of EGCG's hydrophilic intervals facilitated stronger interactions with the aromatic amino acids of LAFs, leading to a conformation change of LAFs from β-Sheet to β-turn. The incorporation of EGCG-LAFs enhanced the network strength of chitosan hydrogels, forming a characteristic meso-network of amyloid fibers, evidenced by a significant increase in gel hardness, reaching a peak value of 2176.71 g. The EGCG-LAFs-chitosan composite hydrogel exhibited excellent antibacterial activity against S. aureus and E. coli , thereby broadening the antibacterial spectrum of LAFs, while exhibiting good biocompatibility. Overall, this study provides a theoretical foundation for the development of functional polyphenol-protein-polysaccharide triphasic composite gels. • EGCG enhances LAFs to form small-particle hinge fiber; • EGCG mainly forms hydrogen bonds with LAFs aromatic residues; • The performance of EGCG-LAFs-CS hydrogel is significantly improved; • Excessive EGCG led to an increase in free water content; • The anti- Escherichia coli ability of hydrogel was significantly enhanced.