Effect of the chain of magnetosomes embedded in magnetotactic bacteria and their motility on Magnetic Resonance imaging

This paper investigates the influence of the magnetosome´s chain, the motility, and the bacterial cell of MC-1 magnetotactic bacteria (MTB) on the Magnetic Resonance imaging (MRI) contrast. Because of its embedded magnetic nanoparticles, that allow magnetic guidance and imaging contrast generation under MRI, magnetotactic bacteria are being considered for therapeutic drug delivery to tumors. In order to separately investigate the different potential sources of contrast in MRI, we used three samples of MC-1 MTB. The first sample was constituted of magnetic bacteria that successfully synthesize magnetic nanoparticles. MC-1 bacteria that do not synthesize magnetosomes form the second sample while the third sample is constituted from dead MC-1 magnetic bacteria containing magnetic nanoparticle. T₂-weighted magnetic resonance images were obtained for multiple echo times. T₂ was then estimated by fitting the signal intensity data for different echo time values to a monoexponential decay curve. It is found that nanoparticles synthesized by MC-1 MTB are the predominant source of contrast in MRI over motion and the cell body.