# Time-Delayed Anticancer Effect of an Extremely Low Frequency Alternating Magnetic Field and Multimodal Protein–Tannin–Mitoxantrone Carriers with Brillouin Microspectroscopy Visualization In Vitro

## TL;DR

This study explores how an alternating magnetic field affects cancer cell carriers loaded with a drug, using a new visualization method to track their impact over time.

## Contribution

The first use of Brillouin light scattering to visualize magnetic nanocarriers in cells and assess their delayed anticancer effects.

## Key findings

- Exposure to a 95 Hz alternating magnetic field most effectively suppressed cancer cell proliferation on the third day.
- Brillouin light scattering detected an increase in magnetic phase with more internalized particles per cell.
- Magnetic carriers did not significantly release their contents or heat up during exposure.

## Abstract

The effect of an extremely low frequency alternating magnetic field (ELF AMF) at frequencies of 17, 48, and 95 Hz at 100 mT on free and internalized 4T1 breast cancer cell submicron magnetic mineral carriers with an anticancer drug, mitoxantrone, was shown. The alternating magnetic field (100 mT; 17, 48, 95 Hz; time of treatment—10.5 min with a 30 s delay) does not lead to the significant destruction of carrier shells and release of mitoxantrone or bovine serum albumin from them according to the data of spectrophotometry, or the heating of carriers in the process of exposure to magnetic fields. The most optimal set of factors that would lead to the suppression of proliferation and survival of cells with anticancer drug carriers on the third day (in comparison with the control and first day) is exposure to an alternating magnetic field of 100 mT in a pulsed mode with a frequency of 95 Hz. The presence of magnetic nanocarriers in cell lines was carried out by a direct label-free method, space-resolved Brillouin light scattering (BLS) spectrometry, which was realized for the first time. The analysis of the series of integrated BLS spectra showed an increase in the magnetic phase in cells with a growth in the number of particles per cell (from 10 to 100) after their internalization. The safety of magnetic carriers in the release of their constituent ions has been evaluated using atomic absorption spectrometry.