Biocompatibility of biodegradable semiconducting melanin films for nerve tissue engineering

Abstract

The advancement of tissue engineering is contingent upon the development and implementation of advanced biomaterials. Conductive polymers have demonstrated potential for use as a medium for electrical stimulation, which has shown to be beneficial in many regenerative medicine strategies including neural and cardiac tissue engineering. Melanins are naturally occurring pigments that have previously been shown to exhibit unique electrical properties. This study evaluates the potential use of melanin films as a semiconducting material for tissue engineering applications. Melanin thin films were produced by solution processing and the physical properties were characterized. Films were molecularly smooth with a roughness (Rms) of 0.341 nm and a conductivity of 7.00 ± 1.10 × 10−5 S cm−1 in the hydrated state. In vitro biocompatibility was evaluated by Schwann cell attachment and growth as well as neurite extension in PC12 cells. In vivo histology was evaluated by examining the biomaterial–tissue response of melanin implants placed in close proximity to peripheral nerve tissue. Melanin thin films enhanced Schwann cell growth and neurite extension compared to collagen films in vitro. Melanin films induced an inflammation response that was comparable to silicone implants in vivo. Furthermore, melanin implants were significantly resorbed after 8 weeks. These results suggest that solution-processed melanin thin films have the potential for use as a biodegradable semiconducting biomaterial for use in tissue engineering applications.

Nanocomposite and Nanostructured Carbon-based Films as Growth Substrates for Bone Cells

“…It is known that electroactive surfaces stimulate the adhesion, growth and specific functions of cells even without their active stimulation with electrical current. For example, Schwann cells cultured on electrically conductive melanin films accelerated their proliferation, and rat pheochromocytoma PC12 cells enhanced extension of their neurites (Bettinger et al, 2009). Similarly, composite nanofibers made of electrically conductive polyaniline blended with poly(L-lactide-co-epsilon-caprolactone) enhanced the adhesion and proliferation of C2C12 murine skeletal muscle myoblasts, as well as their differentiation towards myotubes (Jeong et al, 2008;Jun et al, 2009).…”

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

“…The importance of conductive polymeric composites is based on the hypothesis that such composites can be used to host the growth of cells, so that electrical stimulation can be applied directly to the cells through the composite, proved to be beneficial in many regenerative medicine strategies, including neural and cardiac tissue engineering (Bettinger et al, 2009). Conductive polymers show great promise in biomedicine and are stimulus-responsive polymers that can be synthesized to form composites that could serve as 'smart' biomaterials (Skotheim and Reynolds, 2007).…”

Eumelanin thin films: solution-processing, growth, and charge transport properties

“…low lm hydration) 13,15,20,[22][23][24] or are limited to the determination of the lm conductivity at 100% relative humidity (RH). 21,25 Studies on (partly) hydrated eumelanin lms were commonly performed at high voltages ($10 V), 22,24,25 which might result in undesired currents due to water electrolysis, for example. Furthermore, Au or Ag were typically used as electrode materials in melanin thin lm devices.…”