Visually Intracellular Detection of Telomerase Activity Based on DNA Strand Displacement Reaction and Gold Nanoparticle Labeling

Abstract

Comprehensive SummaryTelomerase, which is regarded as a common biomarker for early cancer diagnostics and a potential target for clinical therapies, has attracted considerable interests concerning its detection and monitoring. Herein, we propose a sensitive method by designing a gold nanoparticle (AuNP) probe for visually intracellular detection of telomerase activity. The AuNPs were functionalized with a telomerase substrate primer (SH‐prime). A 6‐carboxy‐fluorescein (FAM) modified strand (FAM‐probe) was attached to the surface of AuNP through its complementary stand (SH‐attach).In the absence of telomerase, the fluorescence resonance energy transfer (FRET) from FAM to AuNPs results in efficient fluorescence quenching. In the presence of telomerase, SH‐primers on AuNPs were extended with the repeat units (TTAGGG)n. The extension sequence triggered the strand displacement of FAM‐probe to restore the fluorescence signals. It is worth mentioning that the proposed strategy does not need to design complex hairpin structure and allows the measurement of telomerase in crude cell extracts down to 0.5 HeLa cells/μL in 2 h. In addition, the present sensing platform can be applied to the visually intracellular detection of telomerase activity in living cells.