ИСТИНА

One of the distinctive features of nanodiamonds (NDs) is their chemically complex surface thanks to which NDs have many prospective applications. By surface functionalization, one can make NDs more stable, biocompatible or ensure their hydrophobic/hydrophilic properties. Nanodiamonds are highly promising for their application in biomedicine as drug carriers, fluorescent markers, and adsorbents. The success of these applications depends directly on the interactions of NDs with cells, the membrane of which consists of a bilayer made of surfactants. Besides this, addition of surfactants is a well-known method to increase the stability of nanodiamonds suspensions. Therefore, a study of interactions of nanodiamonds with the surrounding molecules including surfactants is highly relevant. We present the results of Raman and fluorescence spectroscopic study of the interactions of detonation nanodiamonds with the ionic surfactants in aqueous suspensions. Aqueous suspensions of sodium octanoate with DNDs having two types of surface functionalization – hydrophobic (DND-H) and hydrophilic (DND-COOH) – were investigated. The research revealed mutual influence of nanoparticles and the surrounding molecules on the properties of each other. The following effects were discovered: 1) DNDs with hydrophobic surface weaken the hydrogen bonds in suspensions more strongly than those with hydrophilic surface, 2) DNDs influence the micelle formation of sodium octanoate, and 3) water molecules and surfactants influence the fluorescence of DNDs. The mechanisms of the observed interactions between hydrophobic/hydrophilic DNDs and the surrounding molecules are proposed.