It is generally well known that the use of magnetic fields has an undoubtedly long-range potential when aided with high substance permeability, although their essential forces must be of low energies. That’s why numerous techniques have been developed to investigate magnetic nanoparticles for biomedical engineering applications to drug-delivery systems (DDSs). On the other hand, judging from the best of our knowledge, there are almost no reported studies of the application of radical pair mechanisms (RPMs) to drug-release controlling under exposure to magnetic fields.
The triplet yield ΦTT affected by magnetic field effects (MFEs), which is equivalent to escape-radical yields with the effects, can be calculated based on RPM as follows: ØT = kT|CT|2/kT|CT|2 + kS(1–|CT|2) where kTT is the release-rate constant of free radicals derived from a triplet radical pair, kSS is the formation-rate constant of a cage product derived from a singlet radical pair, and |CTT|2 is the existence probability of the triplet radical pair. Moreover, in the definite case of kTT=kSS=k, the yield ΦTT as a function of the field strength can be approximated as follows: ØT = k∫0∞|CT|2e–ktdt The preparation of flutamide (FM)-containing liposomes and the field-effect measurements with FM release were carried out in the same way as in our previous reports.
When the magnetic field strength was set up in the range of 0.1–0.2 T, competition between MFEs and the FM-related escape-radical release was observed depending on the field strength. In contrast, MFEs with a field of 40 mT were not extensive under our experimental conditions. Concerning three kinds of liposomes prepared in this study, the field effects obtained using a homogenous field of 0.2 T were more extensive on the order of 67%–75%, than those obtained at a geomagnetic field.
In this study, we considered applying the RPM to DDS methodologies for the best possible balance between clinical performance and low invasivity. Our liposomal drug-release technology with magnetic controls must be one of the most adaptable DDS.
Clinical trial identification
Legal entity responsible for the study
Japan Society for the Promotion of Science (JSPS)
All authors have declared no conflicts of interest.