ИСТИНА

The advantages of porous silicon nanoparticles (PSi NPs) are associated with their low cytotoxicity and good biodegradability in physiological fluids and in living tissues. In this study such informative optical methods as Raman micro-spectroscopy and photoluminescence spectroscopy as well as confocal microscopy were employed for diagnostics of biodegradation of PSi NPs in simulated suspensions and living cells. We used 100 nm nanoparticles with pore diameters of 15±5 nm and specific surface area of 230 m2/g. PSi NPs have been found to have stable structural and optical properties for at least 6 months when stored in water at high concentrations. However, when incubated with cells or when introduced into model biological solutions, the nanoparticles began to dissolve. The PSi NP dissolution processes were studied by changes in their Raman spectra, where a low-frequency shift of the signal maximum, its broadening and a decrease in intensity are observed. Also during the process of dissolving of PSi NPs, their photoluminescence first flared up and then dramatically dropped, which was also noticeable when visualizing nanoparticles in living cells. The reason for this is the decrease in the size of silicon nanocrystals, in which phonon and quantum confinement effects occur.