Synthesis and functionalization of carbohydrate capped silicon nanoparticles for targeting cancer cells

Silicon nanoparticles (SiNPs) hold prominent interest in various aspects of biomedical applications. For this purpose, surface functionalization of the NPs is essential to stabilize them. A facile method is reported here to synthesize highly stable and brightly luminescent amine-terminated SiNPs. The diameter of the crystal cores is 4.6 nm. The NPs emit strong blue-green photoluminescence (PL) at peak position 460 nm with quantum yield (QY) 22%. The NPs exhibited an exceptional stability over a wide pH range (4−14) and are resistant to aging over several weeks. For SiNPs to target specific disease area, and allow them to selectively bind to the cells or the bio-molecules present on the surface of the cells, carbohydrate capped SiNPs were synthesized. However, no such functionalization has been explored with SiNPs. In this study, we report the first synthesis of SiNPs functionalized with carbohydrates (Galactose, Mannose, Glucose and Lactose). The NPs show blue-green luminescence in water and orange luminescence in the dry state with emission of 600nm with the highest QY and exhibit an exceptional stability over weeks. Further study explores the possibility of using carbohydrate capped SiNPs to detect and outline various cell types on the basis of the more physiologically related carbohydrate-receptor interactions. The NPs prove to be very stable in biological media. The toxicity, which was tested both in vitro and in vivo, proved that the NPs were non-toxic. The cellular uptake efficiency was quantified by flow cytometry and indicated that the NPs internalize in the cell within 24 hours. The fluorescence uptake was quantified by both cancer and non-cancerous cell lines and the cancerous cells were shown to uptake more NPs than normal cell lines. The cellular uptake of these NPs, which was visualized by fluorescence and confocal microscopy, showed quick accumulation inside cancer cells within cytoplasm