Magnetic Particle Imaging of Magnetotactic Bacteria as Living Contrast Agents Is Improved by Altering Magnetosome Arrangement

Abstract

Superparamagnetic iron oxide nanoparticles (SPIONs) can be used as imaging agents to differentiate between normal and diseased tissue or track cell movement. Magnetic particle imaging (MPI) detects the magnetic properties of SPIONs, providing quantitative and sensitive image data. MPI performance depends on the size, structure, and composition of nanoparticles. Magnetotactic bacteria produce magnetosomes with properties similar to those of synthetic nanoparticles, and these can be modified by mutating biosynthetic genes. The use of Magnetospirillum gryphiswaldense, MSR-1 with a mamJ deletion, containing clustered magnetosomes instead of typical linear chains, resulted in improved MPI signal and resolution. Bioluminescent MSR-1 with the mamJ deletion were administered into tumor-bearing and healthy mice. In vivo bioluminescence imaging revealed the viability of MSR-1, and MPI detected signals in livers and tumors. The development of living contrast agents offers opportunities for imaging and therapy with multimodality imaging guiding development of these agents by tracking the location, viability, and resulting biological effects.

Precisely Navigated Biobot Swarms of Bacteria Magnetospirillum magneticum for Water Decontamination

“…They move along earth’s magnetic field by producing magnetosome magnetite crystals. , Their innate magnetism allows them to swim farther than their body length per second and spontaneously form clusters, allowing for collective behaviors. , In addition, the high motility of MTB can be actuated by combining with an external magnetic field . MTB have been used in various fields such as medicine, , chemistry, physics, and biotechnology, either as whole cells or as extracted magnetosomes due to their magnetic properties. − However, implementing MTB for the removal of environmental pollutants has not been sufficiently reported . Organophosphorus pesticides ( e.g.…”

Intracellular biotransformation and disposal mechanisms of magnetosomes in macrophages and cancer cells

“…The composition, morphology, and size of magnetosomes vary among bacterial species but are consistent within each of them, reflecting that magnetosome synthesis is under fine genetic control [6], The size of magnetosome cores ranges from 35 to 120 nm [9], a size window in which the particles are single magnetic domains stable at room temperature [6, 8, 10], When isolated from the bacteria, the proteolipidic membrane that envelops the magnetic crystal confers the magnetosomes colloidal stability, prevents their aggregation, and facilitates their functionalization. Given these properties, the good performance of magnetosomes in biomedical applications has been proved as heating agents in magnetic hyperthermia and photothermia to treat cancer [11-13], as drug delivery carriers [14-16], or as contrast agents for magnetic resonance imaging (MRI) [17-20] and for magnetic particle imaging (MPI) [21, 22], Considering the potential of magnetosomes for clinical applications, their fate after they are internalized by the body is an issue that needs to be addressed.…”

“…When isolated from the bacteria, the proteolipidic membrane that envelops the magnetic crystal confers the magnetosomes colloidal stability, prevents their aggregation, and facilitates their functionalization. Given these properties, the good performance of magnetosomes in biomedical applications has been proved as heating agents in magnetic hyperthermia and photothermia to treat cancer [1113], as drug delivery carriers [1416], or as contrast agents for magnetic resonance imaging (MRI) [1720] and for magnetic particle imaging (MPI) [21,22]. Considering the potential of magnetosomes for clinical applications, their fate after they are internalized by the body is an issue that needs to be addressed.…”

An open-source automated magnetic optical density meter for analysis of suspensions of magnetic cells and particles

“…3 Ever since their discovery, 4,5 they have intrigued researchers in the field of magnetism, not in the least because one can easily control them in a microscope. [6][7][8] Magnetotactic bacteria are used as model systems for many applications of magnetic particles, such as magnetic domain imaging, 9,10 hyperthermia, 11,12 magnetic particle imaging, 13 microrobotic manipulation, 14 targeted drug delivery, [15][16][17][18] and studies of spin-wave propagation. 19 Rosenblatt 20 discovered that the transmission of light through suspensions of magnetotactic bacteria is influenced by the direction of an externally applied field.…”