Magnetic Field Triggers Liposome Release

Using confocal laser scanning microscopy, researchers in Europe have determined the release mechanism of a small fluorescent molecule from a lipid vesicle in a low-frequency magnetic field (J. Phys. Chem. Lett., DOI: 10.1021/jz2000936). Because they are biocompatible and can carry a variety of compounds, lipid vesicles are promising drug delivery vehicles. By adding magnetic nanoparticles to the vesicles’ lipid bilayers, scientists can induce liposomes to discharge their small-molecule payloads with an applied alternating magnetic field. In the past, researchers have investigated drug release from lipid vesicles with high-frequency fields (10–500 kHz) that heat the magnetic particles and trigger drug delivery. Low-frequency fields (less than 10 kHz), however, would be safer for in vivo applications. Piero Baglioni of the University of Florence, in Italy, and coworkers report that a 0.2-kHz field leaves magnetic liposomes intact but still causes release of a fluorescent dye through bilayer pore formation, which is promoted by mechanical vibration of cobalt ferrite nanoparticles. The method developed to monitor this model system, the researchers write, can be used to study the release kinetics of drugs, as well as to characterize cell membrane perturbations.