Abstract:
Quantum dots (QDs) present a special type of nanocrystals (NCs)
due to their unique optical and chemical properties. While cadmium-
based QDs (Cd-QDs) have the most favorable physicochemical
properties, their toxicity, instability in the aqueous phase, and loss of
brightness at high temperature are some of the obstacles that prevent the
wide use of Cd-QDs. Carbon-based QDs as graphene quantum dots
(GQDs) represent a very promising biocompatible replacement. In the
present work, we mainly focus on comparing the efficiency and uptake of
GQDs and Cd-QDs for fluorescent imaging purposes and studying the. effect of growing silica shell on the emission and the uptake of QDs
inside living human and bacterial cells. Graphene and CdSe/ZnS QDs
were prepared and encapsulated in silica to increase their emission and
uptake by living cells. Moreover, we studied their photostability and
cytotoxicity. The Prepared G-Si QDs showed good emission inside the
cytoplasmic portion of the liver hepatocellular carcinoma cell line
(HepG2) and Bacillus subtilis (B. subtilis), but they revealed lower
photoluminescence (PL) intensity compared to Si-CdSe/ZnS NCs
although G-Si QDs are advantageous in other aspects, i.e. possess lower
toxicity and higher stability with temperature variations.
