An in situ quenching photoelectrochemical biosensor sensitized with dual-amplification DNA circuit for telomerase activity detection in HeLa cells

Abstract

Abnormal expression of telomerase activity is intimately associated with unrestricted multiplication of tumor cells. As a promising biomarker, precise quantification of telomerase activity provides valuable information for early cancer diagnosis. Here, a novel in situ quenching photoelectrochemical (PEC) biosensor was constructed for the assessment of telomerase activity extracted from HeLa cells. To improve the analytical performance of sensing system, zinc-based metal-organic frameworks (Zn-MOFs) were used as photoelectric active substances and MnO₂ nanoflowers (NFs) served as corresponding quenchers which could catalyze ascorbic acid (AA) to form AA⁺. In situ consumption of electron donor led to the decrease of PEC response. Furthermore, through telomerase activity-dependent intermediate DNA strands triggered entropy-driven catalysis (EDC), the free single-strand DNA fragment was generated on the electrode surface which triggered the subsequent hybridization chain reaction (HCR) and produced the long linear DNA duplexes for loading MnO₂ NFs. Notably, this dual-amplification DNA circuit generated tremendously amplified signals. Thus, the method realized telomerase activity assay with a low detection limit of 18 cells/mL HeLa cells and a dynamic range of 50–1×10⁶ cells/mL. Moreover, the biosensor also demonstrated good selectivity and practical utility for detecting telomerase activity in various cell lines. Thus, the strategy held a promising application in telomerase-related field.