Preparation and characterization of ferromagnetic nickel oxide nanoparticles from three different precursors: application in drug delivery

Three varieties of nickel oxide nanoparticles [NiO(I), NiO(Br) and NiO( Cl)] have been prepared from three simple mononuclear nickel(II) Schiff-base complexes using a pyrolytic technique. The synthesized nanoparticles are characterized by FT-IR, UV-Vis, XRPD, DLS, SEM, TEM and EDX methods. All the techniques suggest the production of highly pure nickel oxides. The magnetic measurements reveal a small hysteresis loop at room temperature, confirming the super-paramagnetic (weak ferromagnetic) nature of the synthesized NiO nanoparticles. We have applied these nanoparticles for drug delivery. For this purpose, erythromycin, the well known broad spectrum antibiotic is conjugated with the NiO nanoparticles to develop NiO(I)-Ery, NiO(Br)-Ery and NiO(Cl)-Ery. These conjugated nanoparticles successfully deliver erythromycin towards both Gram positive and Gram negative bacteria and show effective antimicrobial activity against erythromycin resistant Staphylococcus aureus and Escherichia coli as model microbial species, evidenced from the Minimum Inhibitory Concentration (MIC) and Minimum Bactericidal Concentration (MBC) values. The order of efficiency toward drug delivery is NiO(I)-Ery > NiO(Br)-Ery > NiO(Cl)-Ery. Thus these conjugates can be applied to overcome the drug resistant properties of bacteria which will be a beneficial strategy in anti-bacterial therapy.