ИСТИНА

Nanodiamonds are known for their multifunctional easily modifiable surface that is the origin of both their strong sides as well as their biggest downside within the framework of biomedical applications. Due to the surface, nanodiamonds can be used as a base of bioconjugates and drug carriers, or undergo aggregation into big, hard to pull apart clusters. While the exact mechanism of detonation nanodiamonds’ fluorescence is not known, many authors argue that the fluorescence as well originates from their surface. The popular way to aid nanodiamonds disaggregation is the addition of surfactants to the suspensions. On the other hand, in the biomedical applications the interaction of nanodiamonds with the amphiphilic compounds – close relatives of surfactants – and their micellar structures is unavoidable. The accounting of the influence of such interactions on the fluorescence of nanodiamonds is essential to the proper usage of these nanoparticles in the role of biomarkers. In this study, the influence of the variety of surfactants with different length of hydrocarbon chains on the fluorescence of detonation nanodiamonds with hydrophobic and hydrophilic surfaces was studied using spectroscopic methods. It was found that in general surfactants enhance the fluorescence of carbon nanoparticles, differently with the respect to micellar properties and the lengths of hydrocarbon chains. The hypothesis about the mechanisms of the observed fluorescent changes caused by the interactions of the surfaces of nanodiamonds with the surrounding surfactants is proposed. This study has been performed at the expense of the Russian Foundation for Basic Research (grant №18-32-00779) (A.V. – conducting the experiments, spectra processing), Russian Science Foundation (grant number 17-12-01481) (I.V. – spectra processing, data analysis; T.D. – data analysis). The authors are sincerely grateful to O.Shenderova for providing nanodiamonds.