A Novel Approach for Aerobic Construction of Iron Oxide Nanoparticles by Acinetobacter radioresistens and their Effects on Red Blood Cells

Magnetic iron oxide nanoparticles (MION) with unique surface properties have been widely used in various fields of sciences such as biomedicine. In addition to complicated chemical methods of iron oxide nanoparticles synthesis, there are great concerns regarding their application in vivo. The aims of this study were to investigate both the biologic synthesis of iron nanoparticles and toxic effects of MIONs on red blood cells from healthy and thalassemic blood donors. A Gram negative bacterium was isolated from iron enriched media and was identified as an Acinetobacter radioresistens strain by 16s RNA sequencing. The FTIR, SEM-EDX and XRD analysis results showed that the isolate could synthesize MIONs (≤ 104 nm) in filter sterilized iron enriched media (media with high iron ions) under strict aerobic condition. Further, our results indicated that although none of bacterial or artificial nanoparticles are toxic to Gram positive or negative bacteria but depending of their size and concentration could cause lysis in red blood cells (RBC) and as well as white blood cells (WBC). Toxicity of commercial and bacterial MIONs on peripheral blood cells was evaluated by monitoring hemagglutination, hemolysis and morphological changes. Our data also indicated while lysis occurs in low concentration of nanoparticles but severe hemagglutination is seen in samples treated with commercial nanoparticles (8 nm) beginning at 50μg/mL. The rate of hemolysis and morphological changes was intensified by increasing the concentrations of MIONs. In contrast, the bacterial MIONs did not induce any morphological changes on peripheral blood cells. To our knowledge, this is the first report about construction of nontoxic MIONs by Acinetobacter radioresistens.