The development of methods that can detect telomerase with high selectivity and sensitivity is critical for early diagnosis and treatment of telomerase-related cancers. In this regard, we describe in this work the establishment of a telomerase-initiated and nicking endonuclease-assisted cascade recycling signal amplification approach for non-label and highly sensitive fluorescent detection of telomerase from cancer cells. The target telomerase triggers the elongation of one strand in a partial dsDNA duplex with a pre-designed sequence to induce the release of a ssDNA, which can initiate three cascaded recycling cycles for the generation of many G-quadruplex sequences by cleaving two hairpin signal probes with the assistance of the Nt.AlwI endonuclease. The thioflavin dye further binds these G-quadruplex sequences to exhibit substantial fluorescence enhancement for sensitive detection of telomerase at 8.93 × 10-11 IU. Moreover, this developed method is capable of differentiating telomerase activity among different cancer cells and screening telomerase inhibitors for anticancer drugs.
Keywords: Cascade recycling cycles; Fluorescence; G-quadruplex; Nicking endonuclease; Telomerase.
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