eng Oriental Scientific Publishing Company Biosciences Biotechnology Research Asia 0973-1245 2017-06-28 14 2 631 633 10.13005/bbra/2488 24662 article Hamid Reza Ghorbani 1 Hossein Pazoki 1 Ali Shokuhi Rad 1 Department of Chemical Engineering, Qaemshahr Branch, Islamic Azad University, Qaemshahr, Iran. The development of synthesis routes for oxide nanoparticles is a matter of considerable topical attention. Green synthesis of nanoparticles with the help of microorganisms as reducing agents is an efficient, cost effective, fast and eco-friendly in nature. This paper presents a simple technique to synthesize magnetite (Fe3O4) nanoparticles. In this routine, an aqueous solution of ferrous and ferric salts was mixed with Magnetospirillum and heated for 10 minutes at 70℃. UV–vis absorption spectra, dynamic light scattering (DLS) and transmission electron microscopy (TEM) have been used to illustrate the form process and explain the structure of the magnetite nanoparticles. UV–Vis absorption spectrum showed surface plasmon resonance absorption bands about 240 nm that confirmed magnetite nanoparticles existence. We obtain magnetite nanoparticles of size 42±20 nm after separation and washing procedures by dynamic light scattering (DLS). https://www.biotech-asia.org/vol14no2/synthesis-of-magnetite-nanoparticles-by-biological-technique/  Characterization Magnetospirillum; Magnetite nanoparticles;