Investigating the\nEffect of Polypyrrole–Gelatin/Silk\nFibroin Hydrogel Mediated Pulsed Electrical Stimulation for Skin Regeneration

In clinical practice to treat complex injuries, the application\nof electrical stimulation (ES) directly to the skin complicates the\nwound. In this work, the effect of a conductive hydrogel mediated\nelectric field on skin regeneration is investigated. Polypyrrole incorporated\nmatrices of gelatin and silk fibroin were prepared by two-step interfacial\npolymerization. The maximum electrical conductivity of 10<sup>–4</sup> S cm<sup>–1</sup> was achieved when 200 mM polypyrrole was\nloaded. Mechanically stable and cytocompatible hydrogels were evidenced\nto have antioxidant and blood compatible characteristics. Human dermal\nfibroblast cells responded to pulsed stimulation of 100 or 300 mV\nmm<sup>–1</sup> as observed from the increased expressions\nof TGFβ1, αSMA, and COLIAI genes. Further, the increase\nin the αSMA protein expression with the magnitude of electrical\nstimulation also suggested transdifferentiation of the fibroblast\nto myofibroblast. Moreover, Raman spectroscopy identified two fingerprint\nregions (collagen and lipid) to differentiate ES treated and nontreated\nsamples. Therefore, the combination of hydrogels and electrical stimulation\nhas potential therapeutic effects for accelerating the rate of skin\nregeneration.