As an important
biomarker for early
cancer diagnostics and a valuable therapeutic target,
telomerase has attracted extensive attention concerning its detection and monitoring. Herein, a homogeneous electrochemical strategy based on
T7 exonuclease-aided target recycling amplification is proposed for a simple, rapid, and highly sensitive assay of human
telomerase activity from crude
cancer cell extracts. In this strategy, a 5'
methylene blue (MB)-labeled hairpin (HP) probe is designed, which can hybridize with the
telomerase reaction products to initiate the subsequent digestion by
T7 exonuclease, and a large amount of MB-labeled mononucleotides are released to result in the significantly amplified electrochemical signal. By taking advantage of the high amplification efficiency of T7-aided target recycling, the present assay enables the detection of
telomerase activity at the single-cell level, which is superior or comparable to that of the reported literature. Furthermore, the assay was carried out in a homogeneous
solution without complex modification or immobilization procedures, which has the merits of simplicity, rapid response, and improved recognition efficiency compared with heterogeneous biosensors. With the ability of fast detection, outstanding sensitivity, and excellent selectivity, this strategy offers a convenient and specific method for
telomerase activity detection, which exhibits great potential in the practical application in
telomerase-based early stage
cancer diagnosis.