Effect of Fullerenol C₆₀(OH)₂₄ on Viability and Phagocytic Activity of Human Neutrophils

Water-soluble fullerene derivatives such as fullerenol C₆₀(OH)₂₄ are promising candidates for nanomedicine applications, yet their effects on innate immune cells remain poorly characterized. We investigated the interaction of fullerenol with human neutrophils isolated from healthy donors, exposed to concentrations of 0.25-200 μg/mL over 24-72 h. Using multi-parameter flow cytometry, we assessed viability, apoptosis, phagocytic activity, and intracellular reactive oxygen species (ROS) production, complemented by cell-free DPPH radical scavenging assays. Fullerenol was taken up by neutrophils in a concentration- and time-dependent manner. No significant cytotoxicity was observed up to 100 μg/mL, while viability declined at 200 μg/mL. Phagocytosis of opsonized E. coli was preserved at lower concentrations, though a statistically significant negative correlation with fullerenol concentration was detected at higher doses. In cell-free assays, fullerenol scavenged DPPH radicals with an EC₅₀ of 48.90 ± 10.02 μg/mL, exhibiting slower kinetics than Trolox or ascorbic acid. Critically, fullerenol suppressed intracellular ROS production by >33% at 50 μg/mL following PMA stimulation of neutrophils. These findings demonstrate that fullerenol C₆₀(OH)₂₄ combines potent intracellular antioxidant activity with a favorable neutrophil safety profile, supporting its potential application in oxidative stress-related conditions.