TE-RPA: One-tube telomerase extension recombinase polymerase amplification-based electrochemical biosensor for precise diagnosis of urothelial carcinoma.

Telomerase demonstrates potential as a non-invasive urinary biomarker for urothelial carcinoma (UC); however, current detection methods are either labor-intensive or exhibit suboptimal performance. There is a need for alternative approaches to enable rapid and early diagnosis of UC. In this study, we propose TE-RPA, which combines telomerase extension (TE) with recombinase polymerase amplification (RPA) for one-tube isothermal amplification. The GC content and length of the telomerase substrate were first considered during the screening process. TE-RPA exponential amplification was initiated by the addition of MgOAc along with a forward primer derived from the products of telomerase-mediated extension and a corresponding reverse primer. The amplification product from TE-RPA was subsequently detected using CRISPR-Cas12a system for trans-cleavage of signal probes on the surface of screen-printed electrode in an electrochemical biosensor, resulting in a current change that reflects the corresponding concentration of telomerase. The TE-RPA/CRISPR-Cas12a/electrochemical sensing platform achieves a limit of detection (LOD) for telomerase activity as low as a single-cell level. In addition, the platform attained an area under the curve (AUC) value of 0.9589 in a clinical evaluation involving urine samples from 43 suspected UC patients. Overall, our proposed platform not only offers an efficient method for telomerase isothermal amplification but also provides a portable and precise diagnostic tool for UC.