A multi-recycling amplification-based sensor for label-free and highly sensitive detection of telomerase from cancer cells

Abstract 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.