Adsorption Complexes of Vancomycin with Nanodiamonds: Complexation Kinetics, Composition, and Antimicrobial Properties

Adsorption complexes of vancomycin with detonation nanodiamonds having positive and negative surface charges were obtained. The kinetics of vancomycin adsorption on nanodiamonds is described by a pseudo-second-order equation with similar parameters for both types of nanodiamonds. The kinetics of vancomycin–nanodiamond complexation is described by a pseudo-first-order equation. Using radioactive tracers and IR spectroscopy, it was found that some part of vancomycin is tightly bound to the nanodiamond surface and is not removed during washing. The amount of the tightly bound substance was three times greater for complexes with negative nanodiamonds. However, the retention strength of vancomycin on positive nanodiamonds was higher, and its content changed little during desorption over 10 days. Both types of complexes exhibit identical antimicrobial properties against Staphylococcus aureus. The data obtained support the hypothesis that hydrogen bonding with water molecules plays a key role in the adsorption and retention of vancomycin on the surface of nanodiamonds.