PPy-coated PET fabrics and electric pulse-stimulated fibroblasts

Inherent in biological systems, the electrical field is involved in regulation of many physiological processes. Exogenous electrical stimulation has been used to modulate cellular activity and enhance wound healing. In this study, electrically conductive polypyrrole (PPy) was synthesised through a two-step method and subsequently used to cover the surface of polyethylene terephthalate (PET) fabric microfibres which were used to investigate the effect of electrical pulse on human skin fibroblasts. Scanning electron microscopy (SEM) revealed a very thin, uniform PPy coating on the PET microfibres, which was supported by a surface chemical analysis by X-ray photoelectron spectrometry (XPS). An Instron machine, a thermogravimetric analyser (TGA), and a differential scanning calorimeter (DSC) were used to analyse the mechanical and thermal properties of the fabrics, which showed no significant change following treatment with PPy. The average surface and bulk electrical resistivity of these fabrics were measured to be 63 kΩ per square and 138 ohm m, respectively. The bulk resistivity increased to 213 ohm m after 24 h pre-incubation in cell culture medium, and then increased by another 22% following a pulsed electrical stimulation protocol in cell culture medium for additional 24 h. Human skin fibroblasts were seeded on the PPy-coated PET fabrics and cultivated thereafter with or without pulsed electrical stimulation (P-ES). P-ES was found to enhance fibroblast proliferation, as confirmed by MTT and Hoechst staining. These findings demonstrate that P-ES is effective in promoting fibroblast growth. It also shows that PPy-coated PET fabrics are electrically stable enough to mediate sufficient P-ES. This study therefore lays the groundwork for the use of PPy-coated fabrics to mediate ES in biomedical research.