Offering mild, non-invasive and deep cancer therapy modality, radio frequency (RF) radiation-induced hyperthermia lacks for efficient biodegradable RF sensitizers to selectively target cancer cells and thus avoid side effects. Here, we assess crystalline silicon (Si) based nanomaterials as sensitizers for the RF-induced therapy. Using nanoparticles produced by mechanical grinding of porous silicon and ultraclean laser-ablative synthesis, we report efficient RF-induced heating of aqueous suspensions of the nanoparticles to temperatures above 45-50°C under relatively low nanoparticle concentrations (<1 mg/mL) and RF radiation intensities (1–5 W/cm2). For both types of nanoparticles the heating rate was linearly dependent on nanoparticle concentration, while laser-ablated nanoparticles demonstrated a remarkably higher heating rate than porous silicon-based ones for the whole range of the used concentrations from 0.01 to 0.4 mg/mL. The observed effect is explained by the Joule heating due to the generation of electrical currents at the nanoparticle/water interface. Profiting from the nanoparticle-based hyperthermia, we demonstrate an efficient treatment of Lewis lung carcinoma in vivo. Combined with the possibility of involvement of parallel imaging and treatment channels based on unique optical properties of Si-based nanomaterials, the proposed method promises a new landmark in the development of new modalities for mild cancer therapy.

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The possibility of using mesoporous silicon nanoparticles as amplifiers (sensitizers) of therapeutic ultrasonic exposure were studied experimentally in vitro and in vivo. The combination of nanoparticles and ultrasound led to a significant inhibition of Hep-2 cancer cell proliferation and Lewis lung carcinoma growth in mice. These results indicated good prospects of using silicon nanoparticles as sensitizers for sonodynamic therapy of tumors.

Crystalline silicon (Si) nanoparticles (NPs) doped with iron (Fe) in the range from 0.02 to 2.5 at.% were prepared by plasma-ablative synthesis and were investigated by means of the transmission electron microscopy, X-ray diffraction (XRD), dynamic light scattering (DLS), infrared spectroscopy and nuclear magnetic resonance relaxometry. While the nanocrystal size in Si:Fe NPs did not depend significantly on Fe content, the hydrodynamic diameter of NPs in aqueous suspensions increases from 50 to 180[Formula: see text]nm. Both the transverse and longitudinal proton relaxation time were found to decrease in the prepared suspensions of Si:Fe NPs. Maximal shortening of the transverse relaxion was observed for Si:Fe NPs with 0.2 at.% of Fe and the relaxation rate was almost linearly proportional to the NP concentration. Both these findings and in vivo tests indicate that Si:Fe NPs are promising for biomedical applications in magnetic resonance imaging (MRI) and therapy of cancer.