Water dispersible cross-linked magnetic chitosan beads for increasing the antimicrobial efficiency of aminoglycoside antibiotics.

The aim of this study was to obtain a nano-active system to improve antibiotic activity of certain drugs by controlling their release. Magnetic composite nanomaterials based on magnetite core and cross-linked chitosan shell were synthesized via the co-precipitation method and characterized by Fourier transform infrared spectroscopy (FT-IR), infrared microscopy (IRM), scanning electron microscopy (SEM), dynamic light scattering (DLS), thermogravimetric analysis (TGA) and X-ray diffraction (XRD). The prepared magnetic composite nanomaterials exhibit a significant potentiating effect on the activity of two cationic (kanamycin and neomycin) drugs, reducing the amount of antibiotics necessary for the antimicrobial effect. The increase in the antimicrobial activity was explained by the fact that the obtained nanosystems provide higher surface area to volume ratio, resulting into higher surface charge density thus increasing affinity to microbial cell and also by controlling their release. In addition to the nano-effect, the positive zeta potential of the synthesized magnetite/cross-linked chitosan core/shell magnetic nanoparticles allows for a more favorable interaction with the usually negatively charged cell wall of bacteria. The novelty of the present contribution is just the revealing of this synergistic effect exhibited by the synthesized water dispersible magnetic nanocomposites on the activity of different antibiotics against Gram-positive and Gram-negative bacterial strains. The results obtained in this study recommend these magnetic water dispersible nanocomposite materials for applications in the prevention and treatment of infectious diseases.