Quantum dots from chemical aerosol flow synthesis: Preparation, characterization, and cellular imaging

CdTeSe and CdTeS ternary quantum dots (QDs) that fluoresce in the red to near-IR regions have been prepared using chemical aerosol flow synthesis (CAFS). Changing the composition ratio of Te to Se permits bandgap, tuning of CdTeSe QDs, and replacing selenium with sulfur in the precursor solution increased the quantum efficiency of CdTe QDs up to similar to 37%, because of better surface passivation of the CdS outer shell that grows on top of the CdTe core. ICP-MS and XPS analyses showed the internal structure of these ternary QDs had a gradient in the Se/Te concentration ratio with a CdTe-rich core. A simple phase transfer reaction rendered CdTeSe QDs water-soluble, and the water-soluble CdTeSe QDs were evaluated as a fluorescence labeling agent for intracellular imaging applications. A blue shift in the photoluminescence of CdTeSe QDs was observed over time both in living cells and in solutions under air exposed to light, which is attributed to photo-oxidation of the outer shell.