The integration of biological tissues with conducting polymers is crucial for the advancement of bioelectronics. Although the potential toxicity of some conducting-ink components is an acknowledged constraint for in vivo use, a more fundamental limitation is the lack of molecular understanding of how conducting polymers interact with biological barriers. This study addresses some of the limitations by presenting a novel method for direct polymerization of pyrrole on excised skin in vitro and investigates the evolving skin/conducting polymer interface using electrical impedance spectroscopy (EIS), X-ray diffraction, vapor sorption, and complementary analyses. Direct polymerization of pyrrole on skin is performed by applying an aqueous pyrrole solution to the dermal side and an oxidant (ferric ion solution) on the stratum corneum (SC) side of the skin membrane fixed in a Franz cell. EIS measurements show a marked reduction in skin barrier resistance after PPy formation, whereas control experiments produced the opposite trend, confirming that the resistance drop arises specifically from polymerization. Our complementary analyses indicate that polymerization is primarily localized at the solution-SC interface but also support the formation of an electrically coupled pathway across the barrier. These results provide molecular-level insight into polymer-SC interactions, imply the formation of a coherent conductive junction that extends through the SC layers, and inform the design of future skin-integrated bioelectronic materials. • Franz cell-based methodology is disclosed for pyrrole polymerization on skin surface. • Polypyrrole on skin membranes reduces skin resistance and increases capacitance. • Impedance characteristics are explainable considering nanopores in stratum corneum. • Our results indicate disturbance of lipid organization in stratum corneum.
Virbickas et al. (Sun,) studied this question.