Adsorption complexes of vancomycin with nanodiamonds: formation kinetics, composition, and antimicrobial properties

Adsorption complexes of vancomycin with detonation nanodiamonds having positive and negative surface charges are obtained. The kinetics of vancomycin adsorption on nanodiamonds is described by a pseudo-second-order equation with close parameters for both types of nanodiamonds. The kinetics of vancomycin-nanodiamond complex formation is described by a pseudo-first order equation. Methods of radioactive indicators and IR spectroscopy are used to find that a part of vancomycin is firmly bound to the surface of nanodiamonds and is not removed by washing. The amount of firmly bound matter is found to be three times greater for the complexes with negative nanodiamonds. However, the retention strength of vancomycin on positive nanodiamonds was higher and its content practically did not change during desorption for 10 days. Both types of complexes have the same antimicrobial properties against Staphylococcus aureus. The totality of the obtained data confirms the assumption that the formation of hydrogen bonds with water molecules plays a key role in the adsorption and retention of vancomycin on the surface of nanodiamonds.