Manipulation of Surface Hydration States by Tuning the Oligo(Ethylene Glycol) Moieties on PEDOT to Achieve Platelet‐Resistant Bioelectrode Applications

Abstract Poly(3,4‐ethylenedioxythiophene) (PEDOT) and its derivatives have demonstrated potential in the development of bioelectrodes because of their superior conductivity. However, developing reliable implanted bioelectrodes requires improvements in biocompatibility and the prevention of nonspecific adhesion. In this study, a six ethylene glycol (EG)‐functionalized EDOTs with three different EG lengths (tri‐EG, tetra‐EG, and hexa‐EG) and two types of end groups, hydroxyl ( − OH) and methoxy ( − OCH 3 ) is synthesized and systematically investigated. By coating them on gold electrodes using electropolymerization, the surface and electrochemical properties of these functionalized PEDOT‐coated electrodes are investigated. Although PEDOT with − OH groups on the surface is more hydrophilic, those with − OCH 3 groups on the surface exhibit higher electrochemical activity and lower impedance. The increase in EG units and − OCH 3 groups on the surface effectively reduces the adhesion between the PEDOT and atomic force microscopy tips. PEDOT with longer EG lengths and − OCH 3 groups exhibits relatively few adhered platelets, and the results of the analysis of hydrated states through differential scanning calorimetry are consistent with those of the platelet adhesion test. This study suggests that a tetra(EG)‐functionalized PEDOT with − OCH 3 groups on the surface is a promising coating for implanted bioelectrode applications.