Various types of combinations of amine-containing antibacterial agents (heterocyclic and macrocyclic antibiotics, protein and peptide antibiotics, D-amino acids) and silver nanoparticles stabilized by dicarboxylic (maleic) acid copolymers (AgNPs) are obtained. The study demonstrated the specific action of the conjugates on the planktonic form of gram-positive and gram-negative microorganisms, and fungi. The antimicrobial properties of the conjugates depend on the structures of the AgNPs stabilizing shell, antibacterial agent, and the cell membrane of the pathogen. The polymer shell of the metal nanoparticles allowed to solubilize hydrophobic antibiotics due to the formation of covalent and non-covalent complexes. A pronounced synergistic antimicrobial effect was observed, when AgNPs were combined with hydrophobic amine-containing antibiotics: rifampin—against Staphylococcus aureus and amphotericin B—against Candida albicans. In these cases, the values of Fractional Inhibitory Concentration Indices were lower than 0.5. A pronounced positive bactericidal effect was observed, when using conjugates of AgNPs and a peptide antibiotic (vancomycin) against Enterococcus faecalis, as well as a protein (lysozyme) and D-amino acids against the variety of microorganisms.
Graphic abstract