Effect of ligand-free magnetite nanoparticles prepared by electron beam physical vapour deposition in conjugation with antibiotic

The antibacterial activity of magnetite-based nanocomposites synthesized by electron beam physical vapour deposition (EB PVD) was investigated. The phase, elemental and size composition of the synthesized nanoparticles were confirmed by scanning, transmission, X-ray and dynamic laser spectroscopy methods. The resulting EB PVD magnetite ligand-free nanoparticles (10.7 nm) were stabilized with polyvinylpyrrolidone and conjugated with the β-lactam antibiotic ampicillin, which increased the total particle size to 190 nm. It was found that 2% of the loaded antibiotic was completely released within 3 h according to pseudo-second-order kinetics. Tests on Staphylococcus aureus ATCC 25923 and Escherichia coli ATCC 25922 strains showed high efficiency (minimum inhibitory concentrations 1.24 and 4.93 μg ml−1, respectively), which allows achieving a bacteriostatic effect at a significantly lower concentration of the drug compared with its pure form.