Visible quantum-dot-based targeted siRNA delivery for HIF-1α gene silencing

In the present paper, we synthesized cadmium (Cd) telluride (Te) quantum dots (CdTe QDs) by a hydrothermal method using three different ligands as stabilizers: N-acetyl-L-cysteine (NAC), cysteamine hydrochloride (CA), or 2-(dimethylamino) ethanethiol hydrochloride (DMAE). The results demonstrated that CA-coated CdTe QDs had a higher zeta potential (positive) compared with the NAC- and DMAE-coated CdTe QDs. Furthermore, CA-coated CdTe QDs had greater ability to bind siRNA and greater uptake by human gastric cancer cells (SGC-7901). The release of siRNA from the surface of CdTe QDs was induced by high concentrations of reduced glutathione (GSH). mRNA and protein levels of HIF-1α in SGC-7901 cells were significantly reduced after being treated with the complex of CA-coated CdTe QDs and HIF-1α siRNA under strictly anerobic conditions. In addition, CA-coated CdTe QDs displayed excellent optical properties, good morphology, and low toxicity to normal cells.