Drug-loaded magnetoliposomes with controlled release by low-frequency alternating magnetic field

Controlled release for magnetoliposomes (MLs) can be achieved by using magnetic hyperthermia. However, such approach is not appropriate in the case of the brain tissues and highly perfused organs (kidney, liver, lung).... [ view full abstract ]

Controlled release for magnetoliposomes (MLs) can be achieved by using magnetic hyperthermia. However, such approach is not appropriate in the case of the brain tissues and highly perfused organs (kidney, liver, lung). Moreover, application of high-frequency magnetic field with high intensity during a long time makes the method inconvenient. Our research deals with the non-heating low-frequency alternating magnetic field (LF-AMF). MNPs incorporated into liposomes can respond to an external magnetic field by mechanical rotation (Brown relaxation) and thus destabilize liposomes and induce the release of encapsulated drugs or biomolecules. The aim of this study was to formulate doxorubicin loaded magnetoliposomes (MLs-DOX) for theranostic application and to show the efficiency of LF-AMF application in controlled drug release.

Liposomes were prepared as follows: the film was produced from MNPs, egg lecithine, DSPE-PEG(2000) and cholesterol and then dispersed in phosphate buffe with Dox. Finally, the mixture was sonicated and free MNPs were separated by passing the emulsion through extruder with pore size filter of 400 and 200 nm. Drug excess was removed by centrifugation through NAP-25 desalting column. Animal stage IV human breast cancer 4t1 cells were used for confocal microscopy.

Results and discussion. Under LF-AMF exposure of 15 min the MNPs in MLs firstly aggregated into clusters, then these clusters rotated and destroyed the MLs membranes (data from TEM). As was shown by IR-spectroscopy, the MF application caused “melting” of the MLs membrane, while the “melting” range depended on MF exposure time and MF intensity. In vitro DOX release from MLs under AMF exposures was in 1.5-2 times more effective, than in control experiment (total release for 6 hr under AMF and without was 45% and 25%, respectively).  Cellular internalization was enhenced with MLs-DOX under LF-AMF. It was shown, under 15 min AMF exposure free Dox was around the cell nucleus and lipids were located in cytoplasm as aggregates, in the case of non-treated MLs-DOX there was not free DOX in the cells. The effect depended on AMF parameters. Thus, we showed the possibility of new approach for remote controlled drug release from liposomes.

Grants support: RSF 14-13-00731 and RFBR 16-33-01023.