Comparative Study of Antibacterial Properties of Lysozyme upon Its Adsorption and Covalent Binding to Nanodiamonds

Comparative studies of the antibacterial properties of lysozyme upon its immobilization on nanodiamonds using adsorption and covalent binding are conducted in this work. It is shown that the short incubation period of lysozyme with nanodiamonds in a neutral aqueous medium with a component weight ratio of 1 : 2 is accompanied by the complete adsorption of enzyme on nanoparticles. It is established that 0.20-0.25 mg of lysozyme could be immobilized by covalent binding on 1 mg of nanodiamonds, the surface of which has been pre-activated with benzoquinone. It is elucidated in experiments with Gram-negative (Photobacterium phosphoreum) and Gram-positive (Bacillus subtilis) bacteria that lysozyme immobilized on nanodiamonds by physical adsorption or covalent binding exhibited functional activity and caused the lysis of bacterial cells. It is shown that the catalytic activity of the immobilized lysozyme in both cases decreased in comparison with the free enzyme.