Figure 3.

Drug release is triggered by an alternating magnetic field. (a) Schematic presentation of currently explored directions in nanomedicine and drug delivery that exploit magneto-mechanical actuation of functionalized MNPs in a low-frequency magnetic field. Abbreviations correspond to a low-frequency AMF (LF MF), therapeutic agent (TA), the magnetic moment of (μ), the torque applied to MNP (L), the macromolecule (e.g., enzyme) attached to MNP (MM), and the magneto-mechanical force causing macromolecule deformation (F_MM). A schematic of functionalized MNP is presented having a superparamagnetic core of a radius R_m, a solid shell (e.g., gold) of a radius R_Au, and water-soluble polymeric corona. The hydrodynamic radius of the functionalized MNP is R_HD. Reproduced with permission from [112]. Copyright 2015, Elsevier B.V. (b) Magnetothermally triggered drug delivery systems. Due to the remote and spatiotemporal controllability of AMF, drugs can be released and delivered at a target at the desired time. Various types of drug release systems are possible, based on (i) shrinkage of thermoresponsive polymers, (ii) thermal dissociation of self-assembled nanostructures, and (iii) thermal cleavage of temperature-sensitive linker molecules. Reproduced with permission from [111]. Copyright 2017, Elsevier Ltd.