Eco-friendly synthesis of genipin-crosslinked silk fibroin–silver nanoparticle films with improved mechanical strength and long-term antibacterial stability

Abstract

This study developed an antibacterial film using silver nanoparticles (AgNPs) embedded in a genipin-reinforced regenerated silk fibroin (GSF) matrix. Silk fibroin (SF) efficiently reduces silver ions to stable AgNPs, ensuring their dispersibility and size stability. Genipin, a biocompatible natural crosslinker derived from gardenia, enhances the film’s stability and biocompatibility, aligning with green synthesis principles. Electron microscopy revealed that the GSF-AgNP film has a porous structure with evenly distributed AgNPs, averaging 25 nm in size. This porous morphology increases the material’s surface area, facilitating silver ion release and boosting antibacterial activity. Dynamic light scattering indicated slight aggregation of GSF-AgNPs in solution, though it did not significantly affect antibacterial performance. X-ray diffraction showed that SF reduction and genipin modification confer good dispersibility and partially amorphous characteristics to AgNPs, enhancing material stability and antibacterial properties. Stability tests demonstrated the film’s low solubility in Dulbecco’s Modified Eagle Medium, highlighting its suitability for long-term applications. Antibacterial tests confirmed strong inhibitory effects against Staphylococcus aureus and Escherichia coli, achieving high efficacy with minimal AgNP concentrations. The GSF-AgNP film combines excellent stability and antibacterial potential, making it a promising candidate for biomedical applications, particularly in biological dressings.