An ultrasensitive electrochemical RNA biosensor for mycobacterium tuberculosis detection with hyperbranched primer exchange reaction cascade amplification and sDNA@Au@Pt@UiO-66-NH2 nanozymes

In this study, we introduce an ultrasensitive electrochemical RNA biosensor based on hyperbranched primer exchange reaction (HPER) cascade amplification and Au@Pt@UiO-66-NH₂ nanozymes. This strategy employs catalytic hairpin assembly (CHA) for precise target RNA recognition, which trigger the immobilization of HPER products onto the electrode surface, thereby providing binding sites for nanozymes. Then, the sDNA@Au@Pt@UiO-66-NH₂ signal probes (sDAPU probes) attach to the HPER scaffolds through base-pairing interactions, facilitating signal amplification. The nanozymes catalyze the decomposition of hydrogen peroxide into H₂O and O₂, producing a significantly amplified electrochemical signal. By combining CHA-HPER cascade amplification with the catalytic activity of sDAPU probes, the established biosensor achieves remarkable sensitivity, with a detection limit as low as 14.68 aM, and high specificity that enables the differentiation of non-target pathogen RNA. Furthermore, the biosensor also demonstrates excellent recovery rates in serum samples. Therefore, this electrochemical strategy shows great potential as a diagnostic tool for ultrasensitive Mycobacterium tuberculosis detection.