Fabrication of the conductive polypyrrole/silk fibroin nanofibrous mats and its biodegradable activity

Conductive scaffolds are gaining increasing attention in peripheral nerve repair for their good biocompatibility and electrical properties similar to those of normal nerves. In this study, silk fibroin (SF) nanofibre mats coated with polypyrrole (PPy) were prepared through electrospinning and chemical polymerization. Scanning electron microscopy (SEM) showed even and firm coating of PPy around the nanofibres, and fourier transform infrared spectroscopy (FTIR) analyses of the conductive mats confirmed the presence of hydrogen bonds or electrostatic interactions between PPy and SF. The conductivity of the composite mats could be regulated by varying the pyrrole monomer concentration from 10-20 mM, resulting in corresponding changes in conductivity from 9.4 +/- 3.4 x 10-5 to 4.6 +/- 1.0 x 10-3 S cm-1. The mechanical strength, hydrophilicity and biodegradability of the mats exhibited similar changing trends. Biodegradability tests showed weight losses of 51.2, 13.6, 11.2 and 15.1% for composite mats with varying PPy coating rates on the 28th day, revealing that the biodegradability can be regulated and optimised by varying the pyrrole concentration. Schwann cell culture confirmed that the SF/PPy mats improved cell proliferation and adhesion compared to pure SF mats. The results demonstrate that the SF/PPy mats, with nanoscale surface, excellent biocompatibility, conductivity and controllable biodegradability, represent promising materials with potential for use in peripheral nerve regeneration.