Intermolecular interaction in two-component compounds of nanodiamonds and doxorubicin

Background and Objectives: Detonation nanodiamond (ND) is one of the most promising materials for targeted drug delivery - one of rapidly developing areas of modern chemistry, pharmacology and medicine. Wide possibilities of surface modification and advantageous dimensions make nanodiamonds very attractive objects for using in the drug delivery process. A number of studies have shown that therapeutic efficacy of drugs is enhanced and their toxicities may be attenuated with immobilization on the enriched ND. There are a lot of drug immobilization methods on ND surfacy. Creating a molecular complex due to the hydrogen bond formation caused by supramolecular interaction is one of the simplest. In this work the possibility of drug delivery and retention in cells due to the hydrogen bonds formation between enriched nanodiamonds and highly toxic drugs on an example of doxorubicin is studied by numerical simulation. Materials and Methods: Using the molecular modeling by the density functional theory B3LYP method with 6-31G(d) basic set, we analyze the hydrogen bonds formation and their influence on the IR-spectra and structure of a molecular complex which is formed due to the interaction between doxorubicin and nanodiamonds enriched by carboxylic groups. Numerical modeling of carboxylated nanodiamonds and doxorubicin interaction is based on nanodiamond representation by a diamond-like nanoparticle with a simpler structure. Enriched adamantane (1,3,5,7 -adamantanetetracarboxylic acid) is used as an example of a carboxylated diamond-like nanoparticle. Results: As a result of calculations the combined IR spectrum is obtained as imposing of the IR spectra for doxorubicin and 1,3,5,7-adamantanetetracarboxylic acid various interaction positions. The combined IR spectrum demonstrates a good agreement with experimental data. Conclusions: The obtained results demonstrate that there can be a strong supramolecular interaction between doxorubicin and carboxylated detonation nanodiamonds. The formed hydrogen bonds can be considered as one of the main mechanisms for targeted drug delivery and for drug retention in cells and, thus, for enhancement of doxorubicin therapeutic efficacy.