Fe(II)-substituted cobalt ferrite nanoparticles against multidrug resistant microorganisms

Highlights: • Fe(II)-substituted cobalt ferrite nanoparticles (Nps) against multidrug resistance bacteria. • Synthesis and characterization of L-lysine stabilized cobalt ferrite Nps. • The dependency of antimicrobial activity of ferrite NPs on the cobalt content. The present study is focused on the determination the influence of cobalt content in the magnetic cobalt ferrite nanoparticles (Nps) on their antibacterial efficiency against gram-negative Escherichia coli and gram-positive Staphylococcus aureus bacteria and several Candida species, in particular C. parapsilosis and C. albicans. For the synthesis of Fe(II) substituted cobalt ferrite Nps by co-precipitation way, the L-lysine was used as the capping biocompatible agent and the particle size was successfully controlled to be in the range of 5–6.4 nm. The antimicrobial efficiencies of the Co_xFe_1-xFe₂O₄@Lys Nps, where x varies from 0.2 to 1.0, were evaluated through the quantitative analysis by comparing with that of Fe₃O₄@Lys Nps and l-lysine. In this way, it was evidenced that increase in the Co²⁺ content in the similar sized cobalt ferrite Nps resulted in an increase in their antimicrobial potency into 93.1–86.3 % for eukaryotic and into 96.4–42.7 % for prokaryotic strains. For characterization the composition, structure, and morphology of the tested herein Nps inductively coupled plasma optical emission spectrometry, X-ray diffraction, high-resolution transmission electron microscopy, Mössbauer, and FTIR spectroscopy techniques were conferred.