The functionalization of C60 with such complexes as amino acids has the potential to provide greater interaction between the fullerene and the biological environment yielding potential new medical and pharmacological applications. Although scientific research in the past decade has revealed much about the chemical and physical properties of C60, the biological activities of this compound and its derivatives are still relatively unclear. In an attempt to understand the biological activity of functionalized C60, human epidermal keratinocytes (HEK) were exposed to fullerene-based amino acid (Baa) solutions ranging in concentrations of 0.4-0.00004 mg/mL in a humidified 5% CO2 atmosphere at 37 °C. MTT cell viability after 48 h significantly decreased (p < 0.05) for concentrations of 0.4 and 0.04 mg/mL. In an additional study, human cytokines IL-6, IL-8, TNF-α, IL-1β, and IL-10 were assessed for concentrations ranging from 0.4-0.004 mg/mL. Media was harvested at 1, 4, 8, 12, 24 and 48 h for cytokine analysis. IL-8 concentrations for the 0.04 mg/mL treatment were significantly greater (p < 0.05) than all other concentrations at 8, 12, 24, and 48 h. IL-6 and IL-1β activities were greater at the 24 h and 48 h for 0.4 and 0.04 mg/mL. No significant TNF-α or IL-10 activity existed at any time points for any of the concentrations. These results indicate that concentrations lower than 0.04 mg/mL initiate less cytokine activity and maintain cell viability. In HEK, Baa concentrations of 0.4 and 0.04 mg/mL decrease cell viability and initiate a pro-inflammatory response. © 2006 Elsevier Ltd. All rights reserved.