Cytotoxicity control of silicon nanoparticles by biopolymer coating and ultrasound irradiation for cancer theranostic applications.

Silicon nanoparticles (SiNPs) prepared by mechanical grinding of luminescent porous silicon were coated with a biopolymer (dextran) and investigated as a potential theranostic agent for bioimaging and sonodynamic therapy. Transmission electron microscopy, photoluminescence and Raman scattering measurements of dextran-coated SiNPs gave evidence of their enhanced stability in water. In vitro experiments confirmed the. lower cytotoxicity of the dextran-coated NPs. in comparison with uncoated ones, especially for. high concentrations of about 2 mg ml(-1). Efficient uptake of the NPs. by cancer cells was found using bioimaging in the optical transmittance and photoluminescence modes. Treatment. of the cells with uptaken SiNPs by therapeutic ultrasound for 5-20 min resulted in a strong decrease in. the number of. living cells, while the total number of cells remained nearly unchanged. The obtained data indicate a ` mild' effect of the combined action of ultrasonic irradiation. and SiNPs on cancer cells. The observed results reveal new opportunities for. controlling the photoluminescent and sonosensitizing properties of silicon-based NPs. for applications in the diagnostics and mild therapy of cancer.