Synthesis and cell-imaging applications of glutathione-capped CdTe quantum dots

The aqueous synthesis of glutathione-capped CdTe (GSH-CdTe) quantum dots (QD) with tunable fluorescence in the range of 500-600 nm was analyzed. The synthesis involved adding sulphuric acid dropwise to Al₂Te ₃ to generate H₂Te gas, which was directly bubbled into the CdCl₂ precursor solution under vigorous stirring, followed by heating at 95°C. High-resolution transmission electron microscopy illustrated the crystallinity and high quality of the CdTe nanocrystals. The size of the QD-biotags was critical for labeling fine subcellular features, such as the nucleoli. Upon conjugation with certain small bioprobes, the overall size of GSH-CdTe biolabels could still be as small as 5 nm, which would allow the labeling of fine subcellular organelles. Results show that these QDs can be tuned in fluorescence from green to red and are stable in physiological conditions.