Control of macrophage responses on hydrophobic and hydrophilic carbon nanostructures

This study monitored the expression of cytokines by macrophages and synaptic antigens on macrophages in contact with hydrophobic (water contact angle was 140°) and hydrophilic (water completely adsorbed within 5 s) carbon nanostructures. Results indicated that hydrophilic carbon nanofibers (CNFs) generated the smallest inflammatory response from macrophages compared to hydrophobic CNFs and titanium (which is a conventional prosthetic implant material). Specifically, hydrophilic CNFs triggered less pro-inflammatory cytokine (e.g., tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6)) secretion from macrophages than hydrophobic CNFs. Results further revealed that hydrophobic CNFs activated macrophage cytoskeleton changes in a time dependent manner, whereas hydrophilic CNFs did not. Lastly, although additional tests are needed, the net analysis of macrophage expression of co-stimulatory molecules (e.g., CD80 and CD86) demonstrated that hydrophobic CNFs may ultimately lead to increased T-cell activation than hydrophilic CNFs. In summary, this study suggests that the wettability of carbon nanostructured materials may be potentially linked to macrophage behavior to induce or minimize inflammation.