Silicon nanocrystals as photo- and sono-sensitizers for biomedical applications

Silicon nanocrystals (nc-Si) with sizes of about 2÷5 nm prepared from porous Si act as photosensitizers of the singlet oxygen generation revealed by direct detection of the luminescence at 0.98 eV (1270 nm). In vitro experiments show a suppression of the cancer cell proliferation because of the effect of photo-excited nc-Si. Aqueous suspensions of nc-Si formed by mechanical grinding (milling) of crystalline and porous Si exhibit properties of efficient sonosensitizers. A destruction of cancer cells under ultrasound irradiation in the presence of nc-Si is observed in vitro. Possible applications of nc-Si as photo- and sono-sensitizers for cancer therapy are discussed.