<p>Fullerenols, which possess antioxidants, anti-inflammatory, and neuroprotective properties, can affect mitochondria. The effect of fullerenol C₆₀(OH)₃₆ on the structural-dynamic and functional parameters of mitochondria, both isolated in vitro and in vivo in Wistar rats, was studied. It was found that fullerenol at a dose of 10&#xa0;mg/kg reduced bioenergetic parameters of both glutamate-dependent and succinate-dependent intracellular respiration in vivo. In the in vitro model system, fullerenol at a dose of 0.2&#xa0;mg/ml significantly decreased the oxygen consumption rates in all metabolic states, leading to a reduction in the Lardy and Chance respiratory control ratios and the P/O ratio. Conversely, at a dose of 0.1&#xa0;µg/ml, fullerenols significantly increased these respiratory parameters. Fullerenols, both in vivo and in vitro, increased the viscosity of annular and total mitochondrial membrane lipids. They did not affect the polarity of total lipids but decreased the polarity of annular lipids. Fullerenols at high doses induced significant conformational changes in membrane proteins, increasing their immersion into the lipid matrix. Our results demonstrate that fullerenols modulate mitochondrial bioenergetics and membrane structural dynamics in a dose-dependent manner, which may have implications for understanding both the cytoprotective and potentially cytotoxic effects of these nanoparticles.</p> Graphical abstract <p></p>