Conductive polycatecholamine (or polycatechol)/polypyrrole copolymers enriched in catechol moieties for amperometric sensing application

• Reproducible electrocopolymerisation of catecholamines (or catechol) and pyrrole • PDA/PPy and PNE/PPy copolymers exhibit redox signatures of both catechol and PPy • Copolymers with enhanced electroactivity regarding pristine PDA • Polycatechol(amine)/polypyrrole copolymers with conducting and adhesive character • PDA/PPy with very promising electrochemical transducing capability Polycatecholamines – mostly polydopamine (PDA) – have been employed as functional platforms for (bio)sensing applications due to their recognised adhesive properties. However, their poorly conductive character limits their efficiency as amperometric transducers and hinders their electrochemical growth. In this work, either dopamine (DA), norepinephrine (NE) or catechol (CA) were potentiodynamically copolymerised with pyrrole (Py), a monomer known for forming highly conductive polymers, to incorporate both adhesive and conducting properties into a single polymer. The redox behaviour, wettability, morphology, thickness, dielectric properties and adhesivity of PDA/PPy, PNE/PPy and PCA/PPy were assessed by cyclic voltammetry, electrochemical quartz crystal microbalance, contact angle goniometry, ellipsometry, UV-vis reflectance spectroscopy and atomic force microscopy. The polymers physicochemical properties were tuned by optimising monomer concentrations, proportions and potential sweep rate. Higher deposition rates and electroactivity were reached for all the copolymers, regarding pure PDA or PPy, highlighting the synergistic effect of combining catecholamines or catechol with pyrrole. Their conductive nature was demonstrated through the conversion of redox probes at a broad potential range and corroborated by their dielectric properties. Increasing the concentrations of DA and NE regarding Py, at a high potential scan rate, yields conducting copolymers with a well-defined electrochemical conversion of a PPy-like backbone and strong catechol redox activity. As measured by atomic force spectroscopy, all copolymers displayed stronger adhesion events than pure PPy. Notably, catecholamine copolymers, particularly PDA/PPy, were the most proficient for detecting gallic acid, a polyphenol commonly found in agro-industrial residues, highlighting their potential as electrochemical transduction interfaces.