A sensitive assay of telomerase activity based on the controllable aggregation of quantum dots.

Highlights • Cancer-associated telomerase activity can be detected with QDs-SA biosensor. • The detection limit of telomerase can be down to 13 Hela cells and 9 A549 cells. • The QDs-SA biosensor allows intracellular telomerase tracking and imaging. • Inhibitor screening can be realized in vitro and in vivo. Abstract In order to overcome the shortcomings of traditional methods for telomerase activity detection of time-consuming and susceptibility to interferences in cell extracts, here, we develop a semiconductor quantum dots-streptavidin conjugates (QDs-SA)-based biosensor for sensitive detection of telomerase activity. In the absence of telomerase, the aggregation and thus the fluorescence quenching of QDs-SA can be observed in buffer solution due to charge shielding effect. In the presence of telomerase and biotin-dATP, QDs-SA will bind to telomerase elongation products due to the high affinity between the biotin and streptavidin, protecting the QDs-SA from aggregation and retaining their strong fluorescence. This sensor exhibited good fluorescence responses toward telomerase activity from HeLa cells in the range of 40–1000 cells with a detection limit of 13 cells or A549 cells within the linear range of 20–500 cells with a detection limit of 9 cells. Furthermore, the sensor can be used to efficiently monitor the evolution of telomerase activity in living cells, demonstrating great potential in tumor diagnosis and inhibitor drug screening. [ABSTRACT FROM AUTHOR]