Hybrid fibers containing protein-templated nanomaterials and biologically active components as antibacterial materials

Abstract

The persistent and emerging threat of bacterial infections now extends to many real world scenarios that drive a requirement for antimicrobial fabrics. Such functionalized textiles may find application in protective wear for medical and military personnel and provide functional wound dressings that reduce infection in situ. In this work, biomimetic enzyme entrapment and protein-directed nanomaterials synthesis is combined and applied to the antimicrobial functionalization of fabrics. A multi-faceted approach was adopted to address the fabrication of textiles with Ag nanoparticles, bactericidal proteins and mineral coatings that may contribute (singularly or in unison) to provide antimicrobial activity. Fibroin coordinated silver ions, for example, were chemically reduced to generate silver nanoparticles within the interior of silk fabric fibers. Silk textiles were further functionalized by the surface adsorption of the bactericidal enzyme lysozyme. The exposure of such lysozyme-conjugated fabrics to mineralizing solutions enabled the self-directed immobilization of the enzyme in a subsequent protective matrix of amorphous silica or titania. Silk-immobilized lysozyme was also utilized to adsorb nanocrystalline TiO 2 from solution onto the fabric surface; a subsequent layer of enzyme served to entrap the ceramic particles under a layer of biomimetically mineralized titania. The multiplicity of antimicrobial activities derived from this approach thereby combined; 1) the hydrolytic activity of lysozyme (demonstrated by radial diffusion assays), 2) the bactericidal properties of silver nanoparticles (demonstrated effective against Staphylococcus aureus, Escherichia coli, and silver resistant E. coli) and 3) the photocatalytic bactericidal response of TiO 2 under UV illumination.