A Bipolar Electrode with a Target-Actuated Closed-to-Open State Transition for Synergistic Dual-Inhibition Electrochemiluminescence Sensing.

A nanochannel-gated bipolar electrode (BPE) that undergoes a target-actuated, dynamic transition from a "closed" to an "open" state for ultrasensitive biosensing was successfully developed. This electrochemiluminescence (ECL) sensor leverages a target-induced conformational change in aptamers to control the state of an anodized aluminum oxide (AAO) nanochannel membrane, which separates the two chambers of the BPE system. In the initial "closed" state, the nanochannels are blocked, yielding a high ECL signal. The introduction of the target, deoxynivalenol (DON) toxin, triggers two synergistic inhibition events: it opens the nanochannel gate, transitioning the system to an "open" BPE state that allows a quencher (ascorbic acid) to access the luminophore, and it simultaneously increases the impedance at the BPE cathode, affecting electron transfer. This combination of system state-switching and internal impedance modulation results in a profound signal suppression, leading to a high detection sensitivity. The sensor achieved a detection limit of 0.24 pg·mL-1 for DON over a wide dynamic range. This work presents a new paradigm for biosensor design, moving from static configurations to dynamically reconfigurable electrochemical systems.