Shrayana Ghosh, Amity University Kolkata
In biomedicine and biotechnology, the biosynthesis of magnetic nanoparticles using bacteria could soon play an important role. A process for the isolation and purification of these particles from bacterial cells has now been developed and optimized by researchers from the University of Bayreuth. Magnetosomes exhibited good biocompatibility in initial testing once incubated with human cell lines. Therefore, the findings published in the ‘Acta Biomaterialia’ journal are indeed a promising step towards the biomedical use of magnetosomes in diagnostic imaging techniques or as carriers in implementations for magnetic drug delivery.
The Magnetospirillum gryphiswaldense, a magnetotactic bacterium develops intracellular magnetic nanoparticles, also known as magnetosomes. These are arranged similar to a string of pearls in a chain-like fashion, thus creating a kind of magnetic compass needle that enables the bacteria to travel along the magnetic field of the Earth.
Magnetosomes show a remarkably uniform shape and size of around 40 nanometres, a flawless crystal structure, and promising magnetic properties, as compared to chemically formed nanoparticles. Also, they are surrounded by a biological membrane that, if necessary, can be provided with extra biochemical functionalities. For a variety of biomedical and biotechnological uses, particles are also extremely helpful.
The University of Bayreuth’s interdisciplinary team of scientists has established the quality requirements for purified magnetosomes that are needed for future applications. These include, in particular, the uniformity or the homogeneity of magnetosomes, a high degree of purity, the reliability of the membrane that surrounds and provides stability to each magnetosome. At the same time, a process by which magnetosomes can be gently removed from the bacteria was set up and optimized by the Bayreuth researchers.
The process of magnetosome purification developed in Bayreuth is based on the magnetic nanoparticles’ physical properties. First, by magnetic columns, the magnetosomes are isolated from other non-magnetic cell components. Second, an additional ultracentrifugation step allows the removal of residual impurities due to the high density of the nanoparticles. Physicochemical techniques evaluate the consistency of the distilled magnetosome suspensions.
Even at high particle concentrations, the above analyses revealed elevated vitality values of magnetosome-treated human cell lines, thus indicating good biocompatibility under relevant DIN standards, which is a prerequisite for the use of magnetosomes in magnetic imaging techniques or the magnetically controlled delivery of drugs to target cancer cells.
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Source: Rosenfeldt, S., et al. (2021) Towards standardized purification of bacterial magnetic nanoparticles for future in vivo applications. Acta Biomaterialia. doi.org/10.1016/j.actbio.2020.07.042.
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