Investigating the Extracellular Synthesis of Magnetic Nanoparticles by an Endophytic Bacterium Bacillus sp. Strain BR06 under the Cell-free Extract Strategy

Abstract

Introduction: Magnetic nanoparticles have various biomedical applications such as cell therapy, tissue repair, drug delivery, and magnetic resonance imaging (MRI) due to their unique physical, chemical, thermal, and mechanical characteristics as well as their suitable surface properties. The present study aimed to synthesize magnetic Fe3O4 nanoparticles (NPs) using the interaction of cell-free extracts of endophytic bacterial isolates with Fe2O3 as the precursor of NPs.Materials and Methods: In this study, the extracellular synthesis of Fe3O4 NPs was accomplished by the cell-free extract (CFE) strategy. Characterization of Fe3O4 NPs was performed using different methods, including ultraviolet–visible spectroscopy (UV–Vis), field emission scanning electron microscope (FE-SEM), energy-dispersive X-ray spectroscopy (EDX), X-ray powder diffraction (XRD), and Fourier transform infrared spectroscopy (FTIR).Results: The obtained results of the study showed that the precursor Fe2O3 could be transformed into Fe3O4 NPs with the endophytic strain BR06. Phylogenetic analysis indicated that the isolated strainBR06 belonged to the genus Bacillus, and shared the highest sequence similarity with B. siamensis (MT052693). The Fe3O4 NPs with average diameters of 34 nm and cauliflower shape were synthesized by the endophytic strain BR06 in the biotransformation medium containing 5 mM Fe2O3 after 24 h incubation time. Electron microscopy and the associated spectroscopic analyses confirmed the formation of Fe3O4 NPs.Discussion and Conclusion: In the present study, for the first time, the biosynthesis of extracellular magnetite NPs was described using B. siamensis under the cell-free extract strategy.

Keywords

• biosynthesis
• endophytic bacterium
• nanomagnetite
• cell-free extract
• nanoparticle characterization