Iron gallate-modified silk fibroin microspheres with nanostructured layer for effective antibacterial properties

Abstract

The lack of antibacterial ability in tissue repair materials can lead to repair failure in clinical practice, especially in cases of infection. In this article, an in situ surface modification strategy has been proposed to endow useful biomaterials with excellent antibacterial performance by engineering the surface coordination interaction between iron ions and polyphenols. Through the controlled fabrication of a nanostructured iron gallate (GFe) composite layer on biocompatible silk fibroin microspheres (SFMSs), this study develops an antibiotic-free antimicrobial platform that enables reactive oxygen species (ROS)-mediated bactericidal activity while maintaining the native cell-migration-promoting characteristics of silk fibroin (SF). The resulting biodegradable biomaterial system presents a novel therapeutic strategy for tissue regeneration in infection-prone microenvironments. As a proof-of-concept, silk fibroin microspheres (SFMSs) are selected as the biomaterial matrix and gallic acid (GA) is chosen as the metal ligand materials. The SFMSs are synthesized using a polyvinyl alcohol (PVA) induced β folding method followed by the controlled growth of a layer of the iron gallate nanoparticles (GFe NPs) on its surface, resulting in the formation of GFe NPs modified silk fibroin microspheres (GFe@SFMSs). By harnessing the bacteria-adhesive properties of SF and the reactive oxygen species (ROS) generation catalyzed by Fe³⁺, GFe@SFMSs are capable of efficiently capturing and eliminating bacteria on their surface. The in vitro bacterial studies have demonstrated that GFe@SFMSs exhibit robust antibacterial activity against both Gram-positive and Gram-negative bacteria. The surface coordination engineering strategy between iron ions and polyphenols presents novel prospects for clinical antibacterial application.