Specified simultaneous monitoring of miRNA and telomerase based on fluorescence sensor triggered by H₂O₂-GSH

Simultaneous detection of biomarker telomerase and microRNA (miRNA) would be beneficial for cancer diagnosis. However, developing a unique and universal strategy to further promote the selectivity and specificity of cancer detection remains challenging. Herein, a H₂O₂-glutathione (GSH)-triggered fluorescence sensor (MnO₂-P_sd-P_t-P₂₁, MDT21) based on MnO₂ nanosheets (NSs) for detecting telomerase and miRNA-21 (miR-21) in tumoral cells and tissues is established. Owing to the strong coordination by the DNA phosphate on MnO₂ NSs and the notable addition of NaCl solution, fluorophore/corresponding quencher-labeled telomerase/miR-21 DNA probes and the H₂O₂-GSH-indicated probe would be allowed for adsorption onto MnO₂ NSs, leading to fluorescence quenching. In the presence of the tumoral environment, specific signal molecule H₂O₂-GSH degrades MnO₂ NSs to Mn^{2 +} ions, leading to fluorescence recovery of the H₂O₂-GSH-indicated probe, in turn, further enhancing the selectivity and specificity of the sensor. Moreover, in the presence of the telomerase or miR-21, attributing to the hybridization between the extended telomere strand (TS) primers and telomerase probe as well as miR-21 and miR-21 probe, the corresponding fluorescence would be observed. The H₂O₂-GSH-triggered MDT21 fluorescence sensor enables high-sensitivity and high-selectivity simultaneous detection of telomerase and miR-21 in living cells, mouse tumoral tissues and clinical cancer patient tissue samples. This sensor offers an approach for more accurate detection of biomarkers associated with cancer and thereby represents great potential in clinical diagnosis.