Search

The modification of capsule shells with synthesized magnetic iron oxide nanoparticles aims not only to control the localization of capsules, but also to tune their permeability. The application of a super low frequency non-heating magnetic field (100 Hz) for these purposes offers prospects for high penetration ability into tissues, high locality, and safety, which makes this method preferable for use with in vivo rather than magnetic hyperthermia. In this work, we develop a proof of concept for the remotely controlled release of an encapsulated drug from polyelectrolyte microcapsules under exposure to an alternating super low frequency magnetic field. The characteristics of the tailor-made nanoparticles for the polyelectrolyte shell modification were analyzed to confirm their perspectives as magneto-mechanical actuators due to their abilities with the Brownian relaxation. Polyelectrolyte microcapsules were obtained using the well-known method of sequential deposition of polyelectrolytes on the surface of vaterite particles. We studied the time dependence of the amount of released fluorescently labeled high-molecular weight substance on the frequency of the applied magnetic field (100 mT, 20–100 Hz) and demonstrated that the application of a magnetic field with a frequency of 50 Hz leads to the most pronounced selective increase in the permeability of the shells. Our findings provide a promising application of composite magnetic microcapsules with permeability triggered by a super low frequency magnetic field for the controlled release of drugs without dangerous heating or overheating of the biological tissues. This work was supported by the grant of the President of the Russian Federation (MK-1109.2021.1.3).

Nanosystems for targeted delivery and remote-controlled release of therapeutic agents has become a top priority in pharmaceutical science and drug development in recent decades. Application of a low frequency magnetic field (LFMF) as an external stimulus opens up opportunities to trigger release of the encapsulated bioactive substances with high locality and penetration ability without heating of biological tissue in vivo. Therefore, the development of novel microencapsulated drug formulations sensitive to LFMF is of paramount importance. Here, we report the result of LFMF-triggered release of the fluorescently labeled dextran from polyelectrolyte microcapsules modified with magnetic iron oxide nanoparticles. Polyelectrolyte microcapsules were obtained by a method of sequential deposition of oppositely charged poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) on the surface of colloidal vaterite particles. The synthesized single domain maghemite nanoparticles integrated into the polymer multilayers serve as magneto-mechanical actuators. We report the first systematic study of the effect of magnetic field with different frequencies on the permeability of the microcapsules. The in situ measurements of the optical density curves upon the 100 mT LFMF treatment were carried out for a range of frequencies from 30 to 150 Hz. Such fields do not cause any considerable heating of the magnetic nanoparticles but promote their rotating-oscillating mechanical motion that produces mechanical forces and deformations of the adjacent materials. We observed the changes in release of the encapsulated TRITC-dextran molecules from the PAH/PSS microcapsules upon application of the 50 Hz alternating magnetic field. The obtained results open new horizons for the design of polymer systems for triggered drug release without dangerous heating and overheating of tissues.

Fe3O4 nanoparticles were prepared through solvo-thermal method for further heat transfer applications. TEM, XRD, TGA, and VSM were applied to characterize the obtained nanoparticles. XRD pattern confirmed that nanoparticles were composed of 6-nm crystallites; however, TEM images showed the formation of ca. 75-nm highly dispersed magnetite clusters, made up of about 6-nm nanoparticles. Since, VSM analysis confirmed the superparamagnetic characteristics of Fe3O4 nanoclusters, heat transfer properties of the resulting nanofluids were studied to investigate the influence of the magnetic field on the behavior of the magnetite-based nanofluids. The findings indicated that the convective heat transfer coefficient increased up to 48% and 15%, respectively, for nanofluids containing 0.005 wt% magnetite particles dispersed in water and EG, when the frequency of the alternating magnetic field was changed from 50 Hz to 1 MHz. According to the results, compared to the water-based nanofluids, at higher field amplitudes, the h enhancements of EG-based ones were more pronounced, for instance, at H0 = 36,000 A/m, the h measurements are augmented by about 74% and 109%, respectively, compared to the water and EG as the base fluids. These findings could be explained by the use of specific lost powers of the nanofluids in the exposure of an external alternating magnetic field. [ABSTRACT FROM AUTHOR]

Nanosystems for targeted delivery and remote-controlled release of therapeutic agents has become a top priority in pharmaceutical science and drug development in recent decades. Application of a low frequency magnetic field (LFMF) as an external stimulus opens up opportunities to trigger release of the encapsulated bioactive substances with high locality and penetration ability without heating of biological tissue in vivo. Therefore, the development of novel microencapsulated drug formulations sensitive to LFMF is of paramount importance. Here, we report the result of LFMF-triggered release of the fluorescently labeled dextran from polyelectrolyte microcapsules modified with magnetic iron oxide nanoparticles. Polyelectrolyte microcapsules were obtained by a method of sequential deposition of oppositely charged poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) on the surface of colloidal vaterite particles. The synthesized single domain maghemite nanoparticles integrated into the polymer multilayers serve as magneto-mechanical actuators. We report the first systematic study of the effect of magnetic field with different frequencies on the permeability of the microcapsules. The in situ measurements of the optical density curves upon the 100 mT LFMF treatment were carried out for a range of frequencies from 30 to 150 Hz. Such fields do not cause any considerable heating of the magnetic nanoparticles but promote their rotating-oscillating mechanical motion that produces mechanical forces and deformations of the adjacent materials. We observed the changes in release of the encapsulated TRITC-dextran molecules from the PAH/PSS microcapsules upon application of the 50 Hz alternating magnetic field. The obtained results open new horizons for the design of polymer systems for triggered drug release without dangerous heating and overheating of tissues. [ABSTRACT FROM AUTHOR]

Nanosystems for targeted delivery and remote-controlled release of therapeutic agents has become a top priority in pharmaceutical science and drug development in recent decades. Application of a low frequency magnetic field (LFMF) as an external stimulus opens up opportunities to trigger release of the encapsulated bioactive substances with high locality and penetration ability without heating of biological tissue in vivo. Therefore, the development of novel microencapsulated drug formulations sensitive to LFMF is of paramount importance. Here, we report the result of LFMF-triggered release of the fluorescently labeled dextran from polyelectrolyte microcapsules modified with magnetic iron oxide nanoparticles. Polyelectrolyte microcapsules were obtained by a method of sequential deposition of oppositely charged poly(allylamine hydrochloride) (PAH) and poly(sodium 4-styrenesulfonate) (PSS) on the surface of colloidal vaterite particles. The synthesized single domain maghemite nanoparticles integrated into the polymer multilayers serve as magneto-mechanical actuators. We report the first systematic study of the effect of magnetic field with different frequencies on the permeability of the microcapsules. The in situ measurements of the optical density curves upon the 100 mT LFMF treatment were carried out for a range of frequencies from 30 to 150 Hz. Such fields do not cause any considerable heating of the magnetic nanoparticles but promote their rotating-oscillating mechanical motion that produces mechanical forces and deformations of the adjacent materials. We observed the changes in release of the encapsulated TRITC-dextran molecules from the PAH/PSS microcapsules upon application of the 50 Hz alternating magnetic field. The obtained results open new horizons for the design of polymer systems for triggered drug release without dangerous heating and overheating of tissues.