Biodegradable metal organic framework-mediated DNAzyme/light-up RNA aptamer transcription amplifications for label-free and highly sensitive sensing of telomerase in live cells

Sensitive and specific sensing of intracellular telomerase is of significance for early cancer diagnosis and treatment. And, efficient signal amplification technology is a powerful tool to achieve low level biomarker detection. However, the delivery and release of amplification reagents in live cells is currently a major challenge to achieve sensitive intracellular detection of biomarkers. Here, we describe the development of a powerful in-cell amplification approach for label-free and highly sensitive detection of telomerase in live cells via zeolitic imidazolate framework-8 (ZIF-8)-mediated DNAzyme/light-up RNA aptamer transcription amplification cascades. The amplification reagents can be readily transported into and released in the target cells by ZIF-8 under intracellular acidic environment. Telomerase then activates DNAzyme to trigger the DNAzyme-aided cleavage reaction and T7 RNA polymerase-initiated light-up RNA aptamer transcription cycles for the yield of many light-up RNA aptamers, which associate with the non-fluorescent dye to recover significant fluorescence for achieving intracellular telomerase imaging with high sensitivity in a label-free approach. Moreover, the proposed strategy can discriminate telomerase level variations in different cells and shows promising potentials for anticancer drug screening, which makes such method a robust bioassay for early tumor-related diagnosis and therapeutic monitoring.