This review focuses on one of the most exciting applications area of conjugated conducting polymers, which is tissue engineering. Strategies used for the biocompatibility improvement of this class of polymers (including biomolecules' entrapment or covalent grafting) and also the integrated novel technologies for smart scaffolds generation such as micropatterning, electrospinning, self-assembling are emphasized. These processing alternatives afford the electroconducting polymers nanostructures, the most appropriate forms of the materials that closely mimic the critical features of the natural extracellular matrix. Due to their capability to electronically control a range of physical and chemical properties, conducting polymers such as polyaniline, polypyrrole, and polythiophene and/or their derivatives and composites provide compatible substrates which promote cell growth, adhesion, and proliferation at the polymer-tissue interface through electrical stimulation. The activities of different types of cells on these materials are also presented in detail. Specific cell responses depend on polymers surface characteristics like roughness, surface free energy, topography, chemistry, charge, and other properties as electrical conductivity or mechanical actuation, which depend on the employed synthesis conditions. The biological functions of cells can be dramatically enhanced by biomaterials with controlled organizations at the nanometer scale and in the case of conducting polymers, by the electrical stimulation. The advantages of using biocompatible nanostructures of conducting polymers (nanofibers, nanotubes, nanoparticles, and nanofilaments) in tissue engineering are also highlighted.

Amphiphilic copolymers consisting of an all conjugated polythiophene backbone and sparsely attached oligo-ε-caprolactone side chains have been prepared.

A maleimide monomer with benzoxazine and nitrile functionalities, 1-[3-(4-cyano-phenyl)-3,4-dihydro-2H-benzo[e] [1,3]oxazine-6-yl]-maleimide (MI-Bz-4CN), was prepared using N-(4-hydroxyphenylmaleimide) (HPMI), formaldehyde, and 4aminobenzonitrile. Photoinduced radical polymerization was employed to prepare the alternating copolymers of MI-Bz-4CN with styrene (St) at room temperature using x,x-dimethoxy-x-phenylacetophenone (DMPA) as photoinitiator. These polymers were characterized by FT-IR and 1 H NMR. Monomer reactivity ratios for the studied monomer pair were calculated by using extended Kelen-Tü dos (Ex. K-T) method. Structural parameters of the copolymers were obtained calculating the diad monomer sequence fractions. Copolymers' compositions and the monomer reactivity ratios suggest the alternating nature of the copolymerization. Thermal behavior of the alternating copolymers P(MI-Bz-4CN-alt-St) was also investigated by thermogravimetrical analysis (TGA) and differential scanning calorimetry (DSC). The ring-opening polymerization of the pendant benzoxazine groups of the copolymers was monitored by DSC and FT-IR studies.

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.

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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.