Quantum dot conjugates for targeted silencing of bcr/abl gene by RNA interference in human myelogenous leukemia K562 cells.

Quantum dots (QDs) have been receiving a lot of attention recently for their unique fluorescence properties that can be used in drug discovery and bioimaging applications. We have in this article focused particularly on QDs and used it as a transfection vector as well as a fluorescence label for the RNA interference research. The siRNAs were designed to knock down the bcr/abl oncogene in leukaemia K562 cells. EDAC used as a cross-linker, COOH-functionalized QDs were conjugated with NH2-modified siRNAs to generate QD-siRNA conjugates. We also demonstrated their application to the K562 cells. Using such constructs, the delivery and transfection of siRNAs could be monitored by the presence of fluorescent QDs in the conjugates. QDs not only exhibited superior photostability for labeling cells but also worked as a good vector that remarkably increased the transfection efficiency of siRNAs into the cells. Cell proliferation was examined by the MU assay and cell apoptosis by FACS. Our data have shown that the QD-siRNA conjugates could efficiently inhibit the viability of K562 cells and induced their apoptosis. In summary, QDs can be considered strong tools for the functional analysis of RNAi.