The bioactivity features of shungite nanocarbon (ShC) as a new ultrafine carbon form are of particular interest from the point of view of both biomedical applications of the nanomaterial and environmental issues. Thermodynamic effects of human serum albumin (SA) interaction with ShC in water nanodispersion have been studied regarding the molecular structure and protein fraction content using differential scanning calorimetry.
Deconvolution of the albumin denaturation curve on the basis of Gaussian functions was used to analyze the characteristics (temperature, enthalpy) of individual endothermic transitions of the protein. The increase of the temperature difference of individual transitions was found to be the major SA-ShC interaction effect. No overall thermal destabilization of the protein was observed, although some partial destabilization did occur. This result cannot ensue from changes in intramolecular interdomain interactions in protein molecules at intermolecular interactions with ShC since only a small part of the total protein in nanodispersion has access to nanoparticle surface. The effects observed are shown to be related to the ShC influence on the ratio of the protein fractions with different fatty acids (FA) content by affecting some part of FA at their protein binding sites and their transition to nanoparticles. Protein and nanocarbon probably compete for FA in the process, and their concentration ratio in the dispersion is of decisive importance. The significance of this sort of competition consists in the possibility to influence the transport function of serum albumin with respect to FA.