Cell culture, conducting polymers

Due to the inherent conductivity and electroactivity of conducting polymers, they act as suitable substrates for the in vitro stucfy of excitable cells, including skeletal muscle cells. Biocompatible conducting polymers, such as polypyrrole, polyaniline, and PEDOT, have been used as substrates for the culture of a range of cell types, including PC12 cells, endothelial cells, fibroblasts, and keratinoqftes. 

The direct incorporation of biological dopants into inherently conducting polymers is providing a number of new opportunities in areas such as biosensors, bioreactors, and novel surfaces for cell culturing (see Chapter 1). For example, oligonucleotides have been incorporated directly as dopants,63 as has salmon sperm DNA64 and even intact red blood cells.65... 

PPy is a conductive polymer with several biomedical applications owing to its good biocompatibility and the ability of cells to attach, differentiate and proliferate on its surface [148,149]. In one study, the attachment, proliferation and differentiation of rat MSCs on PPy surfaces was shown to be comparable to those of regular tissue culture plastic surfaces [150]. The synthesis of PPy involves either electrochemical or chemical polymerization, with the admicellar polymerization technique enabling the uniform deposition of thin PPy films from a few to 100 nm thick [151]. Moreover, the attachment of cells to the PPy surface can be improved, for example, via the adsorption of fibronectin or the incorporation of Arg-Gly-Asp (RGD)-containing peptides [152]. Immobilization of the glycosaminoglycans heparin and hyaluronic acid on PPy surfaces was also shown to maintain bone marrow-derived MSC cultures and to induce differentiation successfully into mature osteoblasts [153]. 

It is well known that proliferation or differentiation of nerve or muscle tissue can be enhanced by electrical stimulation, which is in part attributed to the propagation of action potentials upon stimulation. To exploit these physiological events, composites of biodegradable polymers with electroconduc-tive materials have been investigated for effective transmission of electrical signals to the cells cultured on them. PLCL and polyaniline, one of the widely used electrically conductive materials, were mixed to fabricate the nanofiber meshes, illustrating that myotube formation was accelerated when the myoblasts were cultured on polyaniline-containing nanofibers compared to that of PLCL-only nanofibers, even without electrical stimulation (Jun et ah, 2009). Another electroconductive polymer, polypyrrole, was also used as a composite with other synthetic polymers. For example, polypyrrole was incorporated as particles into polylactide scaffolds, and the fibroblasts cultured on them with various intensities of DC current showed controlled proliferation in a current-dependent manner (Shi et al., 2004). 

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