Assessing Cytotoxicity, Endotoxicity, and Blood Compatibility of Nanoscale Iron Oxide Magnetosomes for Biomedical Applications

Magnetosomes are biogenic magnetic nanoparticles with unique material properties, such as high crystallinity and strong magnetization as well as uniform and tunable shapes and sizes. In particular, the ability to genetically modify their enveloping membrane could render isolated magnetosomes as versatile tools for a variety of potential applications in the biomedical field. However, the biocompatibility of the bacterially produced particles has so far not been fully been assessed. In this study, different biocompatibility and toxicity factors of magnetosomes isolated from the model organism Magnetospirillum gryphiswaldense were investigated and tested with THP-1, Jurkat cells, and primary human-derived material such as peripheral blood mononuclear cells (PBMCs). The obtained data demonstrate generally good biocompatibility for all tested magnetosome concentrations as well as high blood compatibility. Only slight but not significant complement activation was observed, with no indications for plasma coagulation or hemolysis. However, the presence of lipopolysaccharides originating from the Gram-negative cell wall of M. gryphiswaldense caused activation of PBMCs expressed as significant cytokine release. Thus, this endotoxicity represents an issue for possible in vivo applications, which needs to be addressed in future studies. Nevertheless, the results show that, overall, magnetosomes have high potential for different (bio)medical applications and are already well-suited for the fields of in vitro diagnostics.