Dual-mode microfluidic biosensor based on catalytic hairpin assembly synergized with bismuth-based MOF-loaded...

Helicobacter pylori infection poses a significant global health threat. The development of portable, accurate and sensitive H. pylori detection equipment is of great importance. In this study, a dual-mode (electrochemical/visual) microfluidic chip integrated with negative control, positive control, and experimental groups was proposed for electrochemical/colorimetric dual-mode detection of H. pylori DNA in saliva. Herein, Fe₃O₄@SiO₂-functionalized H1 as a capture probe for specific recognition of H. pylori nucleic acids, while Bi-MOF@Pt-H2 serves as a signal probe to amplify the response of 3,3',5,5'-tetramethylbenzidine (TMB) oxidation in the presence of H₂O₂ to enable the electrochemical and visual quantification. In the presence of target DNA, hybridization with the capture probe triggers a CHA reaction, and the signaling probe will come out the target DNA and carry out multiple cyclic loops, thus achieving the amplification of the output signal. Under optimal experimental conditions, the multifunctional microfluidic sensor possessed a low detection limit (0.32 fM), robust reproducibility, stability and anti-interference, and achieved an overall accuracy of 90 % in saliva samples. This work establishes a versatile analytical paradigm for point-of-care detection of broad-spectrum pathogenic bacteria through modular aptamer replacement.