Porous silicon as a photosensitizer of generation of singlet oxygen
Porous silicon (P-Si), composed of silicon nanocrystals (nc-Si) with characteristic dimensions of 1-5 nm, has the property of photosensitization of singlet oxygen – an excited state of molecular oxygen, involved in many important biochemical processes. Photosensitivity of generation is observed both in the atmosphere of gaseous oxygen and in various liquid media saturated with molecular oxygen. The mechanism of photosensitivity is a direct electron exchange between the photoexcited nc-Si and the oxygen molecules adsorbed on the surface of nc-Si. The quantitative characteristics and features of this process are studied using spectroscopy, photoluminescence and electron paramagnetic resonance. The results obtained and also the results of experiments in vitro indicate the possibility of using P-Si in the photodynamic therapy of cancer.