Bacterial magnetosomes – nature's powerful contribution to MPI tracer research

Kraupner, Alexander; Eberbeck, Dietmar; Heinke, David; Uebe, René; Schüler, Dirk; Briel, Andreas

doi:10.1039/c7nr01530e

Cited by 51 publications

(45 citation statements)

References 27 publications

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“…The highly squared AC hysteresis loops measured for the aligned bacteria (see Figure ) present a high harmonic distortion on odd harmonics (3rd, 5th, 7th, …), thus making these magnetotactic bacteria very promising candidates for MPI. The suitability of isolated bacterial magnetosomes as MPI tracer has already been reported in the literature …”

Section: Resultsmentioning

confidence: 68%

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Unlocking the Potential of Magnetotactic Bacteria as Magnetic Hyperthermia Agents

Gandia

Gandarias

Rodrigo

et al. 2019

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111

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Magnetotactic bacteria are aquatic microorganisms that internally biomineralize chains of magnetic nanoparticles (called magnetosomes) and use them as a compass. Here it is shown that magnetotactic bacteria of the strain Magnetospirillum gryphiswaldense present high potential as magnetic hyperthermia agents for cancer treatment. Their heating efficiency or specific absorption rate is determined using both calorimetric and AC magnetometry methods at different magnetic field amplitudes and frequencies. In addition, the effect of the alignment of the bacteria in the direction of the field during the hyperthermia experiments is also investigated. The experimental results demonstrate that the biological structure of the magnetosome chain of magnetotactic bacteria is perfect to enhance the hyperthermia efficiency. Furthermore, fluorescence and electron microscopy images show that these bacteria can be internalized by human lung carcinoma cells A549, and cytotoxicity studies reveal that they do not affect the viability or growth of the cancer cells. A preliminary in vitro hyperthermia study, working on clinical conditions, reveals that cancer cell proliferation is strongly affected by the hyperthermia treatment, making these bacteria promising candidates for biomedical applications.

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Section: Resultsmentioning

confidence: 68%

“…The suitability of isolated bacterial magnetosomes as MPI tracer has already been reported in the literature. [59]…”

Section: Magnetic Hyperthermiamentioning

confidence: 99%

Unlocking the Potential of Magnetotactic Bacteria as Magnetic Hyperthermia Agents

Gandia

Gandarias

Rodrigo

et al. 2019

Small

111

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“…Recently, Kraupner and colleagues [ 118 ] compared the use of magnetosomes as a magnetic tracer material in a new diagnostic imaging technology called magnetic particle imaging (MPI), to the use of the gold standard commercial tracer Resovist ® . Results showed a significant increase in particle detection and, consequently, improvement in the resolution of the technique when magnetosomes were applied [ 118 ].…”

Section: Resultsmentioning

confidence: 99%

Applications of Magnetotactic Bacteria, Magnetosomes and Magnetosome Crystals in Biotechnology and Nanotechnology: Mini-Review

et al. 2018

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Magnetotactic bacteria (MTB) biomineralize magnetosomes, which are defined as intracellular nanocrystals of the magnetic minerals magnetite (Fe3O4) or greigite (Fe3S4) enveloped by a phospholipid bilayer membrane. The synthesis of magnetosomes is controlled by a specific set of genes that encode proteins, some of which are exclusively found in the magnetosome membrane in the cell. Over the past several decades, interest in nanoscale technology (nanotechnology) and biotechnology has increased significantly due to the development and establishment of new commercial, medical and scientific processes and applications that utilize nanomaterials, some of which are biologically derived. One excellent example of a biological nanomaterial that is showing great promise for use in a large number of commercial and medical applications are bacterial magnetite magnetosomes. Unlike chemically-synthesized magnetite nanoparticles, magnetosome magnetite crystals are stable single-magnetic domains and are thus permanently magnetic at ambient temperature, are of high chemical purity, and display a narrow size range and consistent crystal morphology. These physical/chemical features are important in their use in biotechnological and other applications. Applications utilizing magnetite-producing MTB, magnetite magnetosomes and/or magnetosome magnetite crystals include and/or involve bioremediation, cell separation, DNA/antigen recovery or detection, drug delivery, enzyme immobilization, magnetic hyperthermia and contrast enhancement of magnetic resonance imaging. Metric analysis using Scopus and Web of Science databases from 2003 to 2018 showed that applied research involving magnetite from MTB in some form has been focused mainly in biomedical applications, particularly in magnetic hyperthermia and drug delivery.

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“…11 In a previous study, magnetosome contrast enhancement was determined to be slightly elevated compared to the former iron oxide-based "gold-standard", Resovist, with a hydrodynamic diameter between 45 and 60 nm and an iron oxide nanoparticle core between only 5 and 6 nm. 11,31 We measured an increased reduction of T2-weighted signal relaxation time of 17.3±2.6 ms for purified magnetosomes with an iron oxide core diameter of approximately 40 nm at an iron concentration of 0.2 mM. This effect on T2 relaxation time reduction exceeded that of commercial, well dispersed magnetite particles with a similar core diameter of 25 nm, for which a value of 31.9±2.6 ms was measured at the same iron concentration ( Fig.…”

Section: Purified Magnetosomes Are Suitable T2-relaxation Contrast Agmentioning

confidence: 99%

Genetic encoding of targeted MRI contrast agents for in vivo tumor imaging

Schuerle¹,

Furubayashi

Soleimany

et al. 2019

Preprint

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Tumor-selective contrast agents have the potential to aid in the diagnosis and treatment of cancer using noninvasive imaging modalities such as magnetic resonance imaging (MRI). Such contrast agents can consist of magnetic nanoparticles incorporating functionalities that respond to cues specific to tumor environments. Genetically engineering magnetotactic bacteria to display peptides has been investigated as a means to produce contrast agents that combine the robust image contrast effects of magnetosomes with transgenic targeting peptides displayed on their surface. This work reports the first use of magnetic nanoparticles that display genetically-encoded pH low insertion peptide (pHLIP), a long peptide intended to enhance MRI contrast by targeting the extracellular acidity associated with the tumors. To demonstrate the modularity of this versatile platform to incorporate diverse targeting ligands by genetic engineering, we also incorporated the cyclic αv integrin-binding peptide iRGD into separate magnetosomes. Specifically, we investigate their potential for enhanced binding and tumor imaging both in vitro and in vivo. Our experiments indicate that these tailored magnetosomes retain their magnetic properties, making them well-suited as T2 contrast agents, while exhibiting increased binding compared to wild-type magnetosomes.

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Bacterial magnetosomes – nature's powerful contribution to MPI tracer research

Cited by 51 publications

References 27 publications

Unlocking the Potential of Magnetotactic Bacteria as Magnetic Hyperthermia Agents

Unlocking the Potential of Magnetotactic Bacteria as Magnetic Hyperthermia Agents

Applications of Magnetotactic Bacteria, Magnetosomes and Magnetosome Crystals in Biotechnology and Nanotechnology: Mini-Review

Genetic encoding of targeted MRI contrast agents for in vivo tumor imaging

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