An amphiphilic, heterografted polythiophene copolymer containing biocompatible/biodegradable side chains for use as an (electro)active surface in biomedical applications

Given that copolymers of complex topology and composition are at the forefront of multifunctional materials research, this work reports an amphiphilic random, heterografted copolymer of (A-g-B)(m)-ran-(A-g-C)(n) type, which was designed to work as an efficient and biocompatible electronic interface. The copolymer (henceforth denoted as PTh-g-(PEG-r-PCL) for simplification) was synthesized in a hierarchical fashion, having pi-conjugated polythiophene (PTh) as the main chain and polar units, polyethylene glycol (PEG) and oligo-epsilon-caprolactone as side chains. The properties of the new copolymer, in solution and in solid state, were evaluated. The applied investigations showed that, due to its amphiphilic character and incompatibility of the side chains, PTh-g-(PEG-r-PCL) experiences microphase separation in solution and film states. By electronic microscopy techniques, two types of supramolecular structures were evidenced: (a) porous spherical particles and (b) rod-like structures. When deposited on carbon electrodes, the copolymer presented a good electroactivity and electrostability. Copolymer's biocompatibility studies, performed by using Cos-1 and Vero cell lines, demonstrated an excellent adhesion when compared with a bare steel electrode while a slight decrease of proliferation was registered, more pronounced for Vero cells, in spite of cell normal growth and morphology. Thanks to its excellent capability for electrochemically interfacing with aqueous electrolytes, the voltammetric oxidation of the NADH coenzyme at the PTh-g-(PEG-r-PCL) film-modified carbon electrode revealed that it can be used as a selective biosensor of this biomolecule, as well.