<title>Silicon nanocrystals as efficient photosensitizer of singlet oxygen for biomedical applications</title>

Abstract

Luminescent silicon nanocrystals (nc-Si) are shown to be efficient photosensitizers of singlet oxygen (SO) generation. Photoluminescence (PL) spectroscopy method is used to study the mechanism and efficiency of the SO photosensitization in gaseous and aqueous ambiences. In vitro experiments demonstrated that the SO, photosensitized by nc-Si dispersed in nutrient solutions, could kill cancer cells. This finding opens a broad opportunity for biomedical applications of nc-Si, e.g. for the photodynamic therapy of cancer or antibacterial treatments.

Spin-Dependent Phenomena in Semiconductor Micro-and Nanoparticles—From Fundamentals to Applications

“…Note, the biocompatibility and biodegradability of nc-Si and por-Si NPs [92,93] together with the photosensitization ability are well satisfied to the modern requirements for PDT application [94]. Besides nc-Si prepared from por-Si [87][88][89][90] the photosensitizing property was also reported for nc-Si prepared by laser ablation of bulk Si in water [86]. This finding indicates a possible way to obtain nc-Si, which can at as stable and efficient photosensitizers for the cancer theranostics [3].…”

“…While por-Si looks rather efficient photosensitizer of the (1) O 2 generation in gaseous atmosphere, the photosensitization by por-Si in liquids and, especially, in aqueous solutions is required for biomedical applications [86][87][88][89][90]. Unfortunately, the fast nonradiative relaxation of (1) O 2 in water complicates detection of the (1) O 2 luminescence.…”

“…This fact is concerned with the (1) O2 generation process under the illumination in the active solution with dispersed nc-Si, because (1) O2 being strong oxidizing substance results in both killing of cells and the inhibitions of cell proliferation [87]. An analysis of the DNA content of the cells incubated with photoexcited por-Si MPs indicates smaller DNA content is typical for the cell death due to the apoptosis mechanism [88]. Mesoporous Si NPs with mean sizes of the order of 100 nm and pore size of 12 nm were used to enhance the photosensitized generation of (1) O 2 with quantum yield~10% in ethanol and 17% in aqueous medium [89].…”