Aptamer Conjugated Quantum Dots for Imaging Cellular Uptake in Cancer Cells

The fluorescence labeling of aptamers is a useful technology for aptamer tracking and imaging on the cells. The aptamer SL₂-B, against the heparin binding domain (HBD) of VEGF₁₆₅ protein, was linked to QDs, producing the QD-SL₂-B aptamer conjugate. The QDs and the QD-aptamer conjugate were characterized and photobleaching effect was studied prior to the cellular incubation. Fluorescence imaging showed that the QD-SL₂-B aptamer conjugate could specifically recognize Hep G2 liver cancer cells and is taken up by the cells without addition of any external transfecting or cell permeabilizing agent. In addition, the results also indicate that incubation time is important for the aptamer cellular uptake and to exhibit its antiproliferative activity on Hep G2 liver cancer cells. This QDs labeling technique provides a new strategy for labeling aptamer molecules for aptamer detection, imaging and understanding their cellular uptake.