Biocompatibility, Pharmaceutical and Biomedical Applications L. Harivardhan Reddy,†,‡ Jose ́ L. Arias, Julien Nicolas,† and Patrick Couvreur*,† †Laboratoire de Physico-Chimie, Pharmacotechnie et Biopharmacie, Universite ́ Paris-Sud XI, UMR CNRS 8612, Faculte ́ de Pharmacie, IFR 141, 5 rue Jean-Baptiste Cleḿent, F-92296 Chat̂enay-Malabry, France Departamento de Farmacia y Tecnología Farmaceútica, Facultad de Farmacia, Campus Universitario de Cartuja s/n, Universidad de Granada, 18071 Granada, Spain ‡Pharmaceutical Sciences Department, Sanofi, 13 Quai Jules Guesdes, F-94403 Vitry-sur-Seine, France

Magnetic nanoparticles: design and characterization, toxicity and biocompatibility, pharmaceutical and biomedical applications.

Magnetotactic Bacteria and Magnetosomes

National Cell Bank, Pasteur Institute of Iran, Tehran 1316943551, Iran, Cardiovascular Research Center, Mount Sinai School of Medicine, New York, New York 10029, United States, Department of General, Organic, and Biomedical Chemistry, NMR and Molecular Imaging Laboratory, University of Mons, Avenue Maistriau, 19, B-7000 Mons, Belgium, Institute for Nanoscience and Nanotechnology, Sharif University of Technology, Tehran 14588, Iran, Department of Biomedical Engineering, National Yang Ming University, No 155, Sec. 2, LiNong Street, Taipei 112, Taiwan, Nanotechnology Toxicology Consulting & Training, Inc., Nova Scotia, Canada, Faculty of Medicine, Dalhousie Medical School, Dalhousie University, Halifax, Nova Scotia, Canada, and Institute for Nanoscale Science and Technology (INSAT), University of Newcastle upon Tyne, Newcastle upon Tyne, NE1 7ER, U.K., Nanotechnology Research Centre, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran

Magnetic resonance imaging tracking of stem cells in vivo using iron oxide nanoparticles as a tool for the advancement of clinical regenerative medicine.

Magnetotactic bacteria derive their magnetic orientation from magnetosomes, which are unique organelles that contain nanometre-sized crystals of magnetic iron minerals. Although these organelles have evident potential for exciting biotechnological applications, a lack of genetically tractable magnetotactic bacteria had hampered the development of such tools; however, in the past decade, genetic studies using two model Magnetospirillum species have revealed much about the mechanisms of magnetosome biogenesis. In this Review, we highlight these new insights and place the molecular mechanisms of magnetosome biogenesis in the context of the complex cell biology of Magnetospirillum spp. Furthermore, we discuss the diverse properties of magnetosome biogenesis in other species of magnetotactic bacteria and consider the value of genetically 'magnetizing' non-magnetotactic bacteria. Finally, we discuss future prospects for this highly interdisciplinary and rapidly advancing field.

Magnetosome biogenesis in magnetotactic bacteria

Magnetic particles offer high technological potential since they can be conveniently collected with an external magnetic field. Magnetotactic bacteria synthesize bacterial magnetic particles (BacMPs) with well-controlled size and morphology. BacMPs are individually covered with thin organic membrane, which confers high and even dispersion in aqueous solutions compared with artificial magnetites, making them ideal biotechnological materials. Recent molecular studies including genome sequence, mutagenesis, gene expression and proteome analyses indicated a number of genes and proteins which play important roles for BacMP biomineralization. Some of the genes and proteins identified from these studies have allowed us to express functional proteins efficiently onto BacMPs, through genetic engineering, permitting the preservation of the protein activity, leading to a simple preparation of functional protein–magnetic particle complexes. They were applicable to high-sensitivity immunoassay, drug screening and cell separation. Furthermore, fully automated single nucleotide polymorphism discrimination and DNA recovery systems have been developed to use these functionalized BacMPs. The nano-sized fine magnetic particles offer vast potential in new nano-techniques.

https://royalsocietypublishing.org/doi/pdf/10.1098/rsif.2008.0170

Formation of magnetite by bacteria and its application.

Magneto immuno-PCR: a novel immunoassay based on biogenic magnetosome nanoparticles.

Magnetotactic bacteria navigate along magnetic field lines usingwell-ordered chains of membrane-enclosed magnetic crystals, referred toas magnetosomes, which have emerged as model to investigate organellebiogenesis in prokaryotic systems. To become divided and segregatedfaithfully during cytokinesis, the magnetosome chain has to be properlypositioned, cleaved and separated against intrachain magnetostaticforces. Here we demonstrate that magnetotactic bacteria use dedicatedmechanisms to control the position and division of the magnetosomechain, thus maintaining magnetic orientation throughout divisionalcycle. Using electron and time-lapse microscopy of synchronized cells ofMagnetospirillum gryphiswaldense, we confirm that magnetosome chainsundergo a dynamic pole-to-midcell translocation during cytokinesis.Nascent chains were recruited to division sites also indivision-inhibited cells, but not in a mamK mutant, indicating an activemechanism depending upon the actin-like cytoskeletal magnetosomefilament. Cryo-electron tomography revealed that both the magnetosomechain and the magnetosome filament are spilt into halves by asymmetricseptation and unidirectional indentation, which we interpret in terms ofa specific adaptation required to overcome the magnetostaticinteractions between separating daughter chains. Our study demonstratesthat magnetosome division and segregation is co-ordinated withcytokinesis and resembles partitioning mechanisms of other organellesand macromolecular complexes in bacteria.

Dirk Schueler

Papers

Magneto immuno-PCR: a novel immunoassay based on biogenic magnetosome nanoparticles.

Magnetosome chains are recruited to cellular division sites and split by asymmetric septation.

Synthetic and biogenic magnetite nanoparticles for tracking of stem cells and dendritic cells

Local Optical Temperature Measurements around Magnetosomes within Single Bacteria to Study Size and Geometry Effects on Heating