Comprehensive study of the electrochemical growth and physicochemical properties of polycatecholamines and polycatechol

Abstract

Catechol is a well-known versatile surface anchoring group that has inspired the development of functional materials, mimicking mussels natural adhesive properties. Polydopamine is the most studied biomimetic polymer, however, the role of other chemical functionalities combined with catechol, on the synthesis and materials properties is far less explored. In this work, we carried out a detailed investigation of the potentiodynamic polymerization of distinct bioinspired catecholamines (dopamine, norepinephrine and L-DOPA) and catechol, disclosing novel insights of their electropolymerization kinetics and final physicochemical properties of the films. The electrochemical data is supported by gravimetry, spectroscopy (FTIR, UV-vis, XPS), atomic force microscopy (AFM), ellipsometry and wettability assays. Highly reproducible and quantitatively deposited electroactive films can be achieved using all the monomers, preserving the original pendant groups. Polydopamine has the fastest initial growth, originating a compact and passivating film, with a more heterogenous structure, whereas polyDOPA has the slowest growth originating a very thin and porous film. Polycatechol and polynorepinephrine displayed the most regular growths, superior electroactivities, and highest adhesion forces towards an amine-modified AFM probe, highlighting the pivotal role of catechol units. This work demonstrates that a controlled electrochemical synthesis of polycatechol, polynorepinephrine and polyDOPA leads to very promising biomimetic materials, alternative to polydopamine, for bioconjugation and electrochemical biosensing applications.