Enhanced physical and biological properties of silk fibroin nanofibers by layer-by-layer deposition of chitosan and rectorite

The search for biodegradable and biocompatible materials applied to the antibacterial field has become a significant topic of interest worldwide. In this study, the electrospinning and electrostatic layer-by-layer self-assembly (LBL) techniques were applied to achieve composite mats with enhanced physical and biological properties. Electrospun silk fibroin (SF) was selected as the substrate, and chitosan (CS) and rectorite (REC) were assembled on the surface of the substrate as positively and negatively charged layers via electrostatic LBL. The morphology, composition and structure of the mats were examined, and the results suggested that LBL modification was successful. In addition, the variation of the bilayer numbers and the component of the outmost layer could affect the morphology and the physical and biological properties of LBL mats. Additionally, the morphology and the water contact angle investigation results of the as-prepared mats indicated that the surface features were changed through the LBL process, resulting in a rougher surface than in pure SF mats. Moreover, the mechanical properties of the SF mats were improved after the LBL process. Furthermore, the antibacterial activity of the LBL self-assembled SF mats against E. coli and S. aureus with a concentration of 10⁶ CFU/mL were 84 and 92%, respectively. The cell-culture experiments demonstrated that the mats maintained superior biocompatibility after the introduction of CS and REC.