Radiofrequency‐Triggered Drug Release from Nanoliposomes with Millimeter‐Scale Resolution Using a Superimposed Static Gating Field

Abstract

Drug delivery to a specific site in the body typically relies on the use of targeting agents that recognize a unique biomarker. Unfortunately, it is often difficult to identify unique molecular signatures that exist only at the site of interest. An alternative strategy is to deliver energy (e.g. light) to locally trigger release from a drug carrier; however, the use of this approach is limited because energy delivery to deep tissues is often impractical or invasive. In this work, radiofrequency-responsive superparamagnetic iron oxide nanoparticles (SPIONs) are used to trigger drug release from nanoscale vesicles. Because the body is inherently non-magnetic, this approach allows for deep tissue targeting. To overcome the unfavorable meter-scale diffraction limit of SPION-compatible radiofrequency (RF) fields, a strong static gating field containing a sharp zero point is superimposed on the RF field. Only drug carriers that are at or near the zero point are susceptible to RF-triggered drug release, thereby localizing drug delivery with millimeter-scale resolution. This approach induces > 40% drug release from thermally-responsive doxorubicin-loaded liposomes within a 3.2 mm radius of the zero point with < 10% release in the surrounding area, leading to a > 2.5 therapeutic index in Huh 7 hepatocellular carcinoma cells.

PMMA-Fe3O4 for internal mechanical support and magnetic thermal ablation of bone tumors

“…Tay ZW, et al shaped magnetic fields to "gate" the heating only to selected regions under MRI guidance 45. Jessica F. Liu, et al developed a magnetic device containing a sharp zero point, allowing for magnetically driven spatially targeted drug release from thermally sensitive liposomal drug carriers 46. Therefore, it is highly necessary to take actions such as performing experiments to evaluate heating and ablation areas.…”

Living, Self‐Replicating Ferrofluids for Fluidic Transport

“…The combined field ensures that effective actuation takes place only at points where the magnetostatic field approaches zero. [50][51][52] Outside the zero point in the selection field, the magnetostatic field locks the magnetic moments of the MTB, ensuring no substantial magnetic torque ( Figure 5D). Using the computational model, the principle was demonstrated by considering the effect of two permanent magnets located at top and bottom of a domain with MTB in three hypothetical parallel channels positioned differently with respect to the magnets.…”

Use of magnetic fields and nanoparticles to trigger drug release and improve tumor targeting

“…Copyright 2018 American Chemical Society) (c) By adding a third magnet, it is possible to independently control the size and location of the field‐free targeting region. (Reprinted with permission from J. F. Liu et al (). Copyright 2018 John Wiley and Sons)…”

“…Recently, we have expanded the use of static gating fields for spatial targeting of AMFs to trigger drug release from thermally sensitive liposomes using a three‐magnet system (J. F. Liu et al, ). The presence of a third magnet “tethers” the field lines to allow for independent control of the size and location of the field‐free region (Figure c).…”