Hydrophobization of silk fibroin nanofibrous membranes by fluorocarbon plasma treatment to modulate cell adhesion and proliferation behavior

Saturated fluorocarbon (CF4) immobilized silk fibroin (SF) nanofibrous membranes were prepared and characterized for biomedical applications. Biocompatible barrier membranes that provide both hydrophobic and hydrophilic surface properties on each side are critical to prohibit soft tissue invasion into localized bone defect. As a barrier membrane, SF nanofibrous mat was fabricated by electrospinning method, and then subsequently modified with water vapor treatment for insolubilization in water and CF4 gas plasma treatment for surface hydrophobization. Morphology of SF nanofibrous mats were observed by scanning electron microscopy. Conformational change of insolubilized SF nanofibers was confirmed by attenuated total reflection-Fourier transform infrared (ATR-FTIR) spectroscopy and C-13 nuclear magnetic resonance (NMR) spectroscopy. Immobilized fluorine atoms on CF4 plasma treated SF nanofibrous membranes were detected using electron spectroscopy for chemical analysis (ESCA). Water contact angle of the SF nanofiber membrane surface was analyzed by varying plasma input power and time. Insolubilized SF nanofibrous membrane maintained nonwoven mat structure without deformation after water immersion. SF nanofibrous membranes showed significant increment of water contact angle from 99.7A degrees to 141.2A degrees by CF4 gas plasma treatment. Fibroblasts on plasma untreated SF nanofibrous membranes were well attached and spread than a control tissue culture polystyrene dish. Fibroblasts on the CF4 gas plasma treated SF nanofibrous membrane showed significantly lower proliferation behavior than plasma untreated SF nanofibrous membranes. Fluorocarbon immobilized SF nanofibrous barrier membrane will be useful for biomedical applications such as a guided bone regeneration.