Electrodeposited poly(3,4-ethylenedioxypyrrole) films as neural interfaces: Cytocompatibility and electrochemical studies

Conducting polymers have been extensively reported as promising coating materials for applications involving interactions with electrically excitable tissues. Specifically, metal electrodes functionalized with conducting polymer coatings have been employed as biointerfaces presenting tailored properties to promote electrode integration as well as chronic functionality. Currently, polypyrrole (PPy) and poly(3,4-ethylenedioxythiophene) (PEDOT) represent the most extensively studied conducting polymers, exhibiting favourable electrochemical properties and biocompatibility. In this paper, we study electrodeposited poly(3,4-ethylenedioxypyrrole) (PEDOP), a conducting polymer which is structurally related to both PEDOT and PPy, and is expected to outperform its “parent” polymers in terms of electrochemical properties and biocompatibility. The performance of PEDOP doped with chloride/phosphate, p-toluenesulfonate or polystyrene sulfonate was subsequently investigated to assess the efficacy of these ionic dopants in promoting electrochemical stability and neural cytocompatibility. Electrodeposited PEDOP films exhibited a high charge storage capacity (50.07 ± 6.96 mC cm ⁻² ), charge injection capacity (203 ± 24 μC cm ⁻² ) and substantial stability (performance loss of 0.49 ± 0.06% after 100 000 stimulation pulses). Furthermore, PEDOP films promoted enhanced neuron outgrowth and viability relative to control substrates. In particular, PEDOP/PTS was shown to increase the average neurite length by a factor of three when compared with cells cultured on bare Pt control substrates. Consequently, due to its favourable electrochemical characteristics together with high neural cytocompatibility, PEDOP can be indicated as a promising alternative to PPy and PEDOT in the field of neural science.