replaced by an exotic amino acid bearing a 3,4-ethylenedioxythiophene ring in the side chain. The incorporation of the peptide at the end of preformed PEDOT chains has been corroborated by both FTIR and X-ray photoelectron spectroscopies. Although the morphology and topology are not influenced by the incorporation of the peptide to the end of PEDOT chains, this process largely affects other surface properties. Thus, the wettability of the conjugates is considerably higher than that of PEDOT, independently of the synthetic strategy, whereas the surface roughness only increases when the conjugate is obtained using a competing strategy (i.e. growth of the polymer chains against termination by end capping). The electrochemical activity of the conjugates has been found to be higher than that of PEDOT, evidencing the success of the polymer-peptide links designed by chemical similarity. Density Functional Theory calculations have been used not only to ascertain the conformational preferences of the peptide but also to interpret the electronic transitions detected by UV-vis spectroscopy. Electroactive surfaces prepared using the conjugates displayed the higher bioactivies in terms of cell adhesion, with the relative viabilities being dependent on the roughness, wettability and electrochemical activity of the conjugate. In addition to the influence of the peptide fragment in the initial cell attachment and subsequent cell spreading and survival, results indicate that PEDOT promotes the exchange of ions at the conjugatecell interface.

The properties, microscopic organization and behavior as the cellular matrix of an all-conjugated polythiophene backbone (PTh) and well-defined poly(ethylene glycol) (PEG) grafted chains have been investigated using different experimental techniques and molecular dynamic simulations. UV-vis spectroscopy has been used to determine the optical band gap, which has been found to vary between 2.25 and 2.9 eV depending on the length of the PEG chains and the chemical nature of the dopant anion, and to detect polaron / bipolaron transitions between band gap states. The two graft copolymers have been found to be excellent cellular matrices, their behavior being remarkably better than that found for other biocompatible polythiophene derivatives [e.g. poly (3,4-ethylenedioxythiophene)]. This is fully consistent with the hydrophilicity of the copolymers, which increases with the molecular weight of the PEG chains, and the molecular organization predicted by atomistic molecular dynamics simulations. Graft copolymers tethered to the surface tend to form biphasic structures in solvated environments (i.e. extended PTh and PEG fragments are perpendicular and parallel to the surface, respectively) while they collapse onto the surface in desolvated environments. Furthermore, the electrochemical activity and the maximum of current density are remarkably higher for samples coated with cells than for uncoated samples, suggesting multiple biotechnological applications in which the transmission with cells is carried out at the electrochemical level.

Graft copolymers formed by anchoring poly(ethylene glycol) (PEG) chains to conjugated polythiophene have been prepared by copolymerizing two compounds: . The electroactivity and electrochemical stability of PTh 3 * -g-PEG is not only higher than that of PTh 5 -g-PEG but also higher than that of PTh 3 , the latter presenting a very compact structure that makes difficult the access and escape of dopant ions into the polymeric matrix during the redox processes. Furthermore, the optical - * lowest transition energy of PTh 3 * -g-PEG is lower than that of both PTh 5 -g-PEG andPTh 3 . These properties, combined with suitable wettability and roughness, result in an excellent behavior as bioactive platform of PTh 3 * -g-PEG copolymers, which are more biocompatible, in terms of cellular adhesion and proliferation, and electro-compatible than PTh 5 -g-PEG.