Closed bipolar electrode-based immunosensing platform with cascade signal amplification for single potential-triggered simultaneous electrochemiluminescence–electrochromic dual-mode detection

Sensitive and accurate detection of tumor markers is crucial for disease diagnosis, yet numerous challenges still exist due to limitations of single-mode assays. This work constructed a universal dual-mode sensing platform combining closed bipolar electrode (cBPE) and split-type immunoassay, which realized simultaneous electrochemiluminescence (ECL) and electrochromic detection of proteins upon a single potential stimulus. Specifically, on the cBPE, L012 served as the ECL emitter at the anode, while Prussian blue (PB) film at the cathode acted as the electrochromic sensing unit. Applying a single potential stimulus could trigger simultaneous ECL emission and the color change from blue PB to white Prussian white. By virtue of MgO 2 @GOx-Ab 2 signal probes as bioprobe, a split-type immunoassay was developed for prostate-specific antigen (PSA) detection. The target-induced production of H 2 O 2 from cascade glucose oxidation and MgO 2 hydrolysis greatly enhanced the anodic ECL signal and facilitated the cathodic PB reduction. Consequently, the strategy achieved the highly sensitive and visual dual-mode assay for PSA, yielding the limits of detection of 2.7 × 10 −12  g/mL for ECL detection and 3.1 × 10 −9  g/mL for electrochromic sensing, respectively. The study opened up an avenue for developing simultaneous multi-mode sensing platforms toward more biomarkers.