An integrated electrochemical POCT platform for ultrasensitive circRNA detection towards hepatocellular carcinoma diagnosis.

Hepatocellular carcinoma (HCC) is the fourth leading cause of cancer-related death. Circ-CDYL, one of the circular RNAs (circRNAs), is recognized as an independent marker for HCC early diagnosis. Point-of-care testing (POCT) of circRNA is essential and in great demand for clinical applications. Herein, we report a fully integrated electrochemical POCT platform for circRNA detection based on Au nanoflowers (AuNFs)/peptide nucleic acid (PNA) modified carbon-fiber microelectrode (CFME). PNA is applied as the recognition element, highly specified for a back-splice junction of circRNA. AuNFs increased active site for PNA probes, improving target-capturing efficiency at an ultralow level. The platform provides a linear range of 10 fM to 1 μM, with a detection limit as low as 3.29 fM. This biosensor demonstrates high specificity towards one-base mismatch and is stable for up to 24 days. The analytical performance has also been verified in human serum samples, demonstrating the potential utility in clinical POCT applications for HCC.