Precise Assembly of Genetically Functionalized Magnetosomes and Tobacco Mosaic Virus Particles Generates a Magnetic Biocomposite

Abstract

Magnetosomes represent magnetic nanoparticles with unprecedented characteristics. Both their crystal morphology and the composition of the enveloping membrane can be manipulated by genetic means, allowing the display of functional moieties on the particle surface. In this study, we explore the generation of a new biomaterial assembly by coupling magnetosomes with tobacco mosaic virus (TMV) particles, both functionalized with complementary recognition sites. TMV consists of single-stranded RNA encapsidated by more than 2100 coat proteins, which enable chemical modification via functional groups. Incubation of EmGFP-or biotin-decorated TMV particles with magnetosomes genetically functionalized with GFP-binding nanobodies or streptavidin, respectively, results in the formation of magnetic, mesoscopic, strand-like biocomposites. TMV facilitates the agglomeration of magnetosomes by providing a scaffold. The size of the TMV−magnetosome mesostrands can be adjusted by varying the TMV−magnetosome particle ratios. The versatility of this novel material combination is furthermore demonstrated by coupling magnetosomes and terminal, 5′-functionalized TMV particles with high molecular precision, which results in "drumstick"-like TMV−magnetosome complexes. In summary, our approaches provide promising strategies for the generation of new biomaterial assemblies that could be used as scaffold for the introduction of further functionalities, and we foresee a broad application potential in the biomedical and biotechnological field.

Microbe‐Mediated Extracellular and Intracellular Mineralization: Environmental, Industrial, and Biotechnological Applications

“…For example, magnetosomes have been incubated of emerald green‐fluorescent protein (EmGFP)‐ or biotin‐decorated TMV particles to generate magnetic nanostrands that express these proteins. [ 333 ] Overexpression of magnetosome membrane proteins may be achieved via sequential chromosomal insertion by transposition to control the size and number of magnetosomes. [ 334 ] This method provides possibility for diverse proteins to be expressed on the magnetosome membrane according to practical requirements.…”

A Versatile Toolkit for Controllable and Highly Selective Multifunctionalization of Bacterial Magnetic Nanoparticles

“…Mickoleit et al, for instance, expressed streptavidin or green fluorescent binding protein (GBP) nanobodies on the particle surface. [ 51 ] The resulting magnetosomes were capable of binding biotin‐ or GFP‐tagged particles of the tobacco mosaic virus, thereby generating a new kind of biocomposite that could serve as magnetic scaffold for adding further functionalities. Moreover, magnetosome expression/coupling of cell signaling ligands might facilitate and stabilize their oligomerization as it was shown for CD40 ligands, [ 52 ] thereby triggering signaling cascades by specific interactions with the corresponding receptors and enabling the in vitro production of therapeutic, polyclonal antibody formulations.…”

Induction of Axonal Outgrowth in Mouse Hippocampal Neurons via Bacterial Magnetosomes

“…In addition, the enveloping membrane is accessible for chemical coupling [20][21][22] or in vivo functionalization by genetic engineering [23]. Previous approaches utilized highly abundant magnetosome membrane proteins as anchor molecules for the display of fluorophores, enzymes, or coupling groups such as antibodies or molecular connectors [24][25][26][27][28][29]. Based on these properties, isolated magnetosomes were already successfully tested in magnetic hyperthermia, as contrast agents for magnetic imaging techniques, as carriers for controlled drug delivery or in cell separation assays [30][31][32][33][34].…”