Nanoscaled Porphyrinic Metal–Organic Frameworks for Electrochemical Detection of Telomerase Activity via Telomerase Triggered Conformation Switch

In this work, we designed a nanoscaled porphyrinic metal-organic framework (PorMOF) with iron porphyrin as linker and zirconium ion as node for electrochemical detection of telomerase activity. The as-prepared PorMOF was characterized with scanning electron microscopy, powder X-ray diffraction, and spectroscopic techniques and demonstrated excellent electrocatalytic activity toward O₂ reduction. Sequentially, the functionalization of PorMOF with streptavidin results in a water-stable electrochemical tracer for detection of telomerase. Upon the telomerase-triggered extension, the assistant DNA 1 (aDNA1)-assistant DNA 2 (aDNA2) duplex could switch into a hairpin structure, and thus, the aDNA2 was released and then hybridized with the capture DNA. Therefore, the PorMOF@SA tracer could be introduced on the electrode surface via biotin-streptavidin recognition, leading to the strong electrochemical signal for readout. The developed approach displayed desirable dynamic range and limitation of detection down to 30 HeLa cells mL^-1. The telomerase activity was 2.2 × 10^-11 IU in a single HeLa cell with good reproducibility and stability. The nanoscaled porphyrinic MOF provided a powerful platform for electrochemical signal transduction and had a promising application in the determination of various biomolecules.