Application of Magnetic Particles in Medicine and Biology

Abstract

Magnetic particles (MPs) have proved to be valuable tools for manipulation of cells or biomolecules, for transportation of chemical substances or transfer of energy to defined target sites in biological systems, and for clinical diagnostics and therapeutics—both in vitro as well as in vivo . MPs receive their magnetic properties and responsiveness to magnetic fields most often from the proven biocompatible iron oxides magnetite (Fe 3 O 4 ) and maghemite (γ‐Fe 2 O 3 ). The small size of MPs allows them to pass through capillary vessels during blood circulation. In nanoparticulate form or under the influence of strong magnetic fields, some MPs can even extravasate through capillary walls into surrounding tissue and reach many of the cells in the human body. Magnetically assisted delivery of chemo‐ or radiotherapeutics to as well as the generation of heat (hyperthermia) at defined target sites in the body can thus be achieved for treatment purposes, such as tumor therapy. Furthermore, MPs can serve as site‐ and function‐specific contrast agents and thus enhance the diagnostic potential of magnetic resonance imaging (MRI). On the biotechnological side, magnetic labeling of cells and biomolecules with MPs followed by magnetic separation has been utilized for the isolation and analysis of nucleic acids and specific cells, for protein purification, for the detection of pathogenic bacteria and viruses, and for gene transfection.

A microfluidic spiral for size-dependent fractionation of magnetic microspheres

“…They are essential for magnetic drug targeting [1] and typically consist of a polymeric matrix material, e.g., albumin, chitosan, and biodegradable polymers poly(lactic acid) (PLA) or poly(lactide-co-glycolide) (PLGA), which enclose a magnetic core, e.g., magnetite or maghemite. The MMS can also enclose a pharmaceutical agent, e.g., chemotherapeutic drugs or blood clot dissolving agents [2,3] and are often coated with (receptor) targeting agents, e.g., antibodies, peptides, and/or with agents improving their stability and blood circulation time, e.g., polyethylene glycols.…”

Magnetic and in vitro heating properties of implants formed in situ from injectable formulations and containing superparamagnetic iron oxide nanoparticles (SPIONs) embedded in silica microparticles for magnetically induced local hyperthermia

“…Heating induction can be further mediated by the magnetic relaxations of so-called magnetic seeds [24]. Even at locations deep within the body, tissue areas enclosing magnetic seeds can be heated [25]. Two heating processes are possible.…”

“…Two heating processes are possible. Large ferro-or ferri-magnetic particles dissipate heat through hysteresis effects in the form of domain wall motion, also called hysteresis losses [25][26][27]. Superparamagnetic nanoparticles allow heating through Brownian or Né el magnetic relaxation [28][29][30][31][32].…”

Biomedical Applications of Multiferroic Nanoparticles

“…Membrane depolarization changes the transition rates, according to (1), and affects the stationary probability distribution among all Markov states. The transitions are thermally activated and are stochastic in nature.…”

“…Magnetic nanoparticles with functionalized surfaces have recently found numerous applications in biology, medicine and biotechnology [1,2]. Some application concern in vitro applications such as magnetic tweezers and magnetic separation of proteins and DNA molecules.…”