Referenced-Closed Bipolar Electrode to Enable the Photoelectrochemical-Electrochromic Synchronous Biosensing

The environment of electrolyte solution (e.g., saline, pH, and ascorbic acid) can affect the stability of electrochromic materials in photoelectrochemical (PEC)-electrochromic biosensors. Herein, we develop a referenced-closed bipolar electrode (ref-CBPE)-enabled PEC-electrochromic biosensing platform for synchronous dual-modal detection. The CBPE serves as an engine driving redox reactions in PEC and electrochromic detection cells, effectively avoiding the interference of the electrolyte solution environment with the polyaniline electrochromic material. Furthermore, we discuss how to choose the most appropriate CBPE-enabled PEC-electrochromic type to maximize the biosensor response. The ref-CBPE-enabled PEC-electrochromic biosensor, incorporating a reference electrode to provide stable potential reference, exhibits a higher signal response and 40-fold photocurrent amplification compared to a conventional CBPE configuration. For biosensor design, type II CdSe QDs/ZnO heterojunctions act as the driving anode to provide electrons for polyaniline as the driving cathode, enabling the synchronous acquisition of PEC and electrochromic signals. Taking the Cry1Ab protein as the model target, a miniaturized and portable dual-modal biosensing device is constructed using 3D printing technology, which reveals high portability, selectivity, and accuracy. The work provides a new avenue for developing a portable PEC-electrochromic biosensing device of dual-signal synchronous acquisition.