Among the numerous attempts to integrate tissue engineering concepts into strategies to repair nearly all parts of the body, neuronal repair stands out. This is partially due to the complexity of the nervous anatomical system, its functioning and the inefficiency of conventional repair approaches, which are based on single components of either biomaterials or cells alone. Electrical stimulation has been shown to enhance the nerve regeneration process and this consequently makes the use of electrically conductive polymers very attractive for the construction of scaffolds for nerve tissue engineering. In this review, by taking into consideration the electrical properties of nerve cells and the effect of electrical stimulation on nerve cells, we discuss the most commonly utilized conductive polymers, polypyrrole (PPy) and polyaniline (PANI), along with their design and modifications, thus making them suitable scaffolds for nerve tissue engineering. Other electrospun, composite, conductive scaffolds, such as PANI/gelatin and PPy/poly(e-caprolactone), with or without electrical stimulation, are also discussed. Different procedures of electrical stimulation which have been used in tissue engineering, with examples on their specific applications in tissue engineering, are also discussed.

https://onlinelibrary.wiley.com/doi/pdf/10.1002/term.383

Application of conductive polymers, scaffolds and electrical stimulation for nerve tissue engineering.

Polyaniline is one of the most important conducting and responsive polymers. A molecular mechanism for the oxidation of aniline is proposed. This mechanism explains the specific features of aniline oligomerization and polymerization in various acidity ranges. The formation of polyaniline precipitates, colloids and thin films is reviewed and discussed on the basis of the chemistry of aniline oxidation. The generation of nanostructures, i.e. granules, nanotubes, nanowires and microspheres, is also considered. Oligomers containing phenazine constitutional units play an important role in self-assembly to form templates. Polyaniline chains then grow from these templates and produce the various individual morphologies. Copyright © 2008 Society of Chemical Industry

The mechanism of the oxidative polymerization of aniline and the formation of supramolecular polyaniline structures

Polyaniline nanofibres can be prepared by a number of methods based on chemical oxidative polymerization and in situ adsorption polymerization. However, the lack of alignment in these nanostructures makes them unsuitable for many applications. Here, we report a simple approach to chemical oxidative polymerization that can control the growth and simultaneous alignment of polyaniline nanofibres grown on a range of conducting and non-conducting substrates in a wide variety of sizes. The diameters of the tips of the nanofibres can be controlled within the range 10-40 nm, and the average length can be controlled within the range 70-360 nm. Moreover, the coatings display a range of properties including superhydrophilicity and superhydrophobicity. Such nanostructured coatings may be useful for applications such as anti-fog coatings, self-cleaning surfaces, DNA manipulation, transparent electrodes for low-voltage electronics, and chemical and biological sensors.

Growth and alignment of polyaniline nanofibres with superhydrophobic, superhydrophilic and other properties.

K. Tzou

Papers

Kinetic study of the chemical polymerization of aniline in aqueous solutions

A method to prepare soluble polyaniline salt solutions — in situ doping of PANI base with organic dopants in polar solvents

Improved solution stability and spinnability of concentrated polyaniline solutions using N,N′-dimethyl propylene urea as the spin bath solvent

Influence of the doping conditions on the surface energies of conducting polymers

Mechanically strong, flexible highly conducting polyaniline structures formed from polyaniline gels