Synthesis of α-Fe2−xAgxO3 nanocrystals and study of their optical, magnetic and antibacterial properties

Abstract

To be an implicit disinfectant, inorganic nanoparticles have to show chemical stability, minimum cytotoxicity and effective bactericidal activity. Among metal oxide nanoparticles, iron oxide demonstrates a very high structural stability in corrosive biological environments and also has a relatively non-toxic profile in comparison with other metal nanoparticles such as ZnO. Iron oxide nanoparticles also exhibit bacterial growth inhibition properties on a wide spectrum of bacterial species mainly by generating reactive oxygen species (ROS) from water and oxygen. However, the efficiency of their antibacterial activity remains low. Probably, the main reason behind this is the aggregation and occurrence of large flocculates of nanoparticles in aqueous media due to their hydrophobic nature and hence their interaction with bacteria is limited. To overcome all these problems, in this study we incorporate silver ions into α-Fe₂O₃ to produce magnetic hybrid nanostructures with better colloidal stability and enhanced antibacterial activity due to their synergistic effect. The antibacterial activity of the prepared nanospheres was tested at 3 different concentrations (450, 600, 750 μg) against four bacterial strains – Bacillus subtilis, Staphylococcus aureus, Pseudomonas fluorescens and Escherichia coli using a disc diffusion method. The nanospheres showed a concentration dependent activity profile and remarkably, they were very effective against B. subtilis and P. fluorescens. Their antibacterial effect was found to be comparable to the standard antibiotic streptomycin used in this study. Furthermore, in this work structural, optical and magnetic properties of the prepared samples have been studied using different characterization tools.