Studies on the thermal sensitivity of lung cancer cells exposed to an alternating magnetic field and magnesium-doped maghemite nanoparticles

Magnetic fluid hyperthermia (MFH) represents a promising therapeutic strategy in cancer utilizing the heating capabilities of magnetic nanoparticles when exposed to an alternating magnetic field (AMF). Because the efficacy and safety of MFH treatments depends on numerous intrinsic and extrinsic factors, therefore, the proper MFH setups should focus on thermal energy dosed into the cancer cells.

In this study, we performed MFH experiments using human lung cancer A549 cells (in vitro) and NUDE Balb/c mice bearing human lung (A549) cancer (in vivo). In these two experimental models, the heat was induced by magnesium-doped iron(III) oxide nanoparticles coated with mPEG-silane (Mg_0.1-γ-Fe₂O₃(mPEG-silane)_0.5) when exposed to an AMF.

We observed that the lung cancer cells treated with Mg_0.1-γ-Fe₂O₃(mPEG-silane)_0.5 (0.25 mg·mL⁻¹) and magnetized for 30 min at 14.4 kA·m⁻¹ yielded a satisfactory outcome in reducing the cell viability up to ca. 21% (in vitro). The activation energy calculated for this field strength was estimated for 349 kJ·mol⁻¹. Both volumetric measurements and tumor mass assessments confirmed by magnetic resonance imaging (MRI) showed a superior thermal effect in mice bearing human lung cancer injected intratumorally with Mg_0.1-γ-Fe₂O₃(mPEG-silane)_0.5 nanoparticles (3 mg·mL⁻¹) and subjected to an AMF (18.3 kA·m⁻¹) for 30 min four times at weekly intervals. Research demonstrated that mice undergoing MFH exhibited a marked suppression of tumor growth (V = 169 ± 94 mm³; p < 0.05) in comparison to the control group of untreated mice. The CEM43 (cumulative number of equivalent minutes at 43 °C) value for these treatments were estimated for ca. 9.6 min with the specific absorption rate (SAR) level ranging from 100 to 150 W·g⁻¹.

The as-obtained results, both cytotoxic and those related to energy calculations and SAR, may contribute to the advancement of thermal therapies, concurrently indicating that the proposed magnetic fluid hyperthermia holds a great potential for further testing in the context of medical applications.