Decreased macrophage density on carbon nanotube patterns on polycarbonate urethane

Nanotechnology is creating materials that can regenerate numerous tissues (including those used for bone, vascular, cartilage, bladder, and neuronal systems) better than what is currently being implanted. Despite this promise, little is known about the functions of wound healing cells (such as macrophages) on nanomaterials. Carbon nanotubes are intriguing nanomaterials for implantation due to their unique biologically inspired surface, electrical, and mechanical properties. For the above reasons, the objective of the present study was to investigate macrophage function on one promising type of nano-implant material for orthopedic applications (carbon nanotubes microscopically aligned on polymers). To align carbon nanotubes on polymers, a novel imprinting method placing carbon nanotubes in grids of defined spacings (from 30 to 100 microm) on a polymer matrix was developed. In this study, the selective adhesion and proliferation of macrophages after 4 h, 24 h, and 4 days on aligned regions of a currently implanted polymer (specifically, polycarbonate urethane) compared to aligned carbon nanotube patterns were found. That is, decreased macrophage functions were observed in this study on aligned regions of carbon nanotubes compared to polycarbonate urethane. The present in vitro study, thus, provided evidence of the ability of carbon nanotubes to down-regulate macrophage adhesion and proliferation which is important to decrease a harmful persistence wound-healing reaction to orthopedic implants.