Characterization of electroconductive blends of poly(HEMA-co-PEGMA-co-HMMA- co-SPMA) and poly(Py-co-PyBA)

Electroconductive hydrogels (ECH) prepared as blends of UV-cross-linked poly(hydroxyethylmethacrylate) [p(HEMA)]-based hydrogels and electropolymerized polypyrrole (PPy) were synthesized as coatings on microlithographically fabricated interdigitated microsensor electrodes (IMEs) and microdisc electrode arrays (MDEAs). Hydrogels were synthesized from tetraethyleneglycol diacrylate (TEGDA), hydroxyethylmethacrylate (HEMA), polyethyleneglycol monomethacrylate (PEGMA), N-[tris(hydroxymethyl)methyl]-acrylamide (HMMA), and 3-sulfopropyl methacrylate potassium salt (SPMA) to produce p(HEMA-co-PEGMA-co-HMMA-co-SPMA) hydrogels. The conductive polymer was synthesized from pyrrole and 4-(3′-pyrrolyl)butyric acid by electropolymerization within the electrode-supported hydrogel. ECH films produced with different electropolymerization charge densities were investigated using cyclic voltammetry, electrical impedance spectroscopy, differential scanning calorimetry (DSC), and thermal gravimetric analysis (TGA). Polymer morphology was studied by SEM. The ECH demonstrated the desired characteristics of high electrical conductivity (low impedance), as well as high thermal stability compared to pure hydrogel. Signal enhancement was achieved by modifying the surface of an MDEA biotransducer with the ECH, with a 10-fold increase in the voltammetric current response associated with the ferrocene monocarboxylic acid (FcCO₂H) redox reaction.