Sensitive detection of telomerase activity in cells using a DNA-based fluorescence resonance energy transfer nanoprobe.

Telomerase activity is inhibited in normal somatic cells but abnormally high in the majority of cancer cells. Maintenance of active telomerase in cancer cells promotes proliferation and immortalization. With the difference in telomerase activity between cancer and normal cells in mind, we designed a nanoprobe based on quantum dot (QD) and fluorescence resonance energy transfer (FRET). The nanoprobe consisted of a specific sequence of DNA with the two ends labeled with QD as a fluorescent donor and Alexa488 as a fluorescent acceptor, respectively. FRET signal tracking was performed by adjusting the distance between donors and acceptors, and changes in the FRET signal shown to be related to telomerase activity. Incubation of cells with the nanoprobe facilitated sensing of intracellular telomerase activity, and consequent discrimination between normal and cancer cells. Our novel DNA nanoprobe based on QD-FRET achieved sensitive detection of telomerase in cells up to a detection limit of one cell, and quantitative detection of telomerase activity in different numbers of cells. The nanoprobe generated in this study is expected to allow dynamically monitoring of the changes in telomerase activity in cells under treatment with drugs, providing a potential basis for early diagnosis and management of cancer.