Quantum-confinement effect in silicon nanocrystals during their dissolution in model biological fluids

In present work, we studied the mechanisms of dissolution of porous silicon nanoparticles (PSi NPs) during their incubation in model liquids, i.e. water and phosphate buffered saline (PBS) at 37$^\circ$ С. The methods of transmission electron microscopy (TEM), photoluminescence (PL) spectroscopy, and Raman spectroscopy were used. According to TEM images, PSi NPs consist of silicon nanocrystals (nc-Si) 2–10 nm in size and pores. It is shown that incubation of PSi NPs in water leads to enhancement of their PL, accompanied by a slight decrease in the size of nc-Si, which is associated with the passivation of defects and stabilization of the oxide shell of nanocrystals. During incubation in PBS, a significant quenching of PL and disappearance Raman signal of the PSi NPs took place. That indicates rapid dissolution of PSi NPs. We presented phenomenological model describing how quantum-confinement effect affects properties of nc-Si during their dissolution.