Research Information System
European Polymer Journal, vol.67, pp.99-112, 2015 (SCI-Expanded)
© 2015 Elsevier Ltd. All rights reserved.Silk based nanofibers are potential carrier systems for the controlled delivery of antibiotics and other antimicrobial agents. For silk based biomaterials, silk morphology; random coil (Silk I) or β sheets (Silk II) is an important factor affecting their mechanical, thermal and hydrolytic stability and also release of drug/biocides. In this study, Ag/fibroin composite nanofibers were produced in the form of both random coil (Silk I) and β sheet (Silk II) morphologies via glutaraldehyde vapor and methanol post-treatments, respectively and effect of fibroin morphology on Ag ion release and concomitant antibacterial activity was investigated. Ag nanoparticles were synthesized in fibroin nanofibers with diameter of 200-600 nm, by reduction of Ag ions to Ag0. It was proven that random coil (Silk I) and β sheet (Silk II) morphologies cause significant differences on Ag+ release profiles, thermal properties and hydrolytic stability of nanofibers. According to the kinetics data, Ag+ was released by the first order kinetics for both random coil and β sheet (Silk II) morphologies during the first 8 h. However, due to crystalline structure of the fibers, the cumulative release of silver ions from β sheet structure (Silk II) was lower than random coil (Silk I) structure. Furthermore, according to the disc diffusion test results for both nanofiber structures, containing 1% (w/v) of AgNO3, clear zones of inhibition were observed against Staphylococcus aureus, Staphylococcus epidermidis and Pseudomonas aeruginosa.