(559f) Towards a Biocompatible Conductive Nanotube Film: An In-Depth Investigation Into Cellular Biocompatibility

Single-walled carbon nanotubes (SWNTs) have shown promise for use in organic electronic applications including thin film transistors, conducting electrodes, and biosensors. There is a current need to rapidly process SWNTs from solution phase to substrates in order to produce device structures. In terms of SWNT film deposition, previous studies were able to adsorb SWNTs by drop casting, airbrush spray coating, spin coating, vacuum filtration, electrophoretic deposition, and Langmuir-Blodgett deposition. Furthermore, researchers have found that surfaces covalently functionalized with primary amines have been shown to selectively adsorb semiconducting SWNT. However, this and similar techniques are dependent upon environmentally sensitive surface modification techniques. Hence, we explored the potential of substrates modified with physisorbed polymers, poly(L-lysine) (PLL), as a possible alternative methodology. In this work, we detail a number of methods for depositing SWNTs onto various substrate materials using amine-rich PLL and other methods of covalently functionalizing the surface with primary amines. Furthermore, devices were constructed using these methods to observe if cell movement on the surface would elicit changes in the device performance. SWNT adsorption and alignment were characterized by atomic force microscopy (AFM). SWNT surface density was strongly dependent upon the adsorbed concentration of PLL on the surface, spin coating speed, and SWNT solution concentration. Another benefit for using PLL as an adhesion layer was for its biocompatibility with cells. Results from examining mitochondrial hydrogenase activity and  Live/Dead fluorescence assay suggest that the PLL SWNTs spin-coat devices exhibited higher biocompatibility with NIH-3T3 fibroblast cells than the drop cast SWNTs devices possibly due to differences of substrate surface roughness. To further elucidate the effect of SWNT roughness on biocompatibility, cell morphology was observed on substrate surfaces of varying SWNT network density using a spray coating method. Additional cells lines with relevant characteristics were also tested for their biocompatibility which included C2C12 myotubes and cardiomyocytes. Furthermore, to observe if cell contractile forces on the device surfaces would elicit a change in electrical performance, 2-terminal resistance measurements were taken at different stages of cell adhesion onto the surface. We envision these conducting biocompatible SWNT networks could potentially be used as biosensors to investigate cell adhesion mechanics or provide a method for cancer diagnostics.