MXene@BiOBr‐Mediated Liposome Amplification for Accumulation‐Mode Organic Photoelectrochemical Transistor Immunoassay With In Situ Signal Amplification

ABSTRACT Organic photoelectrochemical transistor (OPECT) biosensing technology represents an innovative platform with significant amplification capabilities at the intersection of optoelectronics and biological systems. However, research in this field has predominantly focused on depletion‐mode operation. Small‐molecule amines can effectively dope poly(ethylenedioxythiophene): poly(styrene sulfonate) (PEDOT: PSS), which will enable the transition of transistor operation from depletion mode to enhancement mode without compromising device performance, thereby opening new avenues for innovative biomedical applications. In this study, a liposome‐amplified combined with MXene@BiOBr (MXBiOBr)‐gated accumulation‐mode OPECT biosensor was developed for highly sensitive detection of okadaic acid (OA). Leveraging the strong photocurrent response of MXBiOBr to dopamine (DA), competitive immunoassays were conducted using OA‐BSA‐dopamine‐loaded liposome (OA‐BSA‐DLL) conjugates in the presence of OA. Following lysis treatment, the released dopamine was introduced into an electrode electrochemical cell, which enhanced the photocurrent of MXene@BiOBr and amplified the device response. As a result, high‐performance detection of OA was achieved with a detection limit as low as 0.12 p M . A notable highlight of this study lies in the liposome‐amplified MXBiOBr‐gated OPECT architecture, which not only establishes a novel universal platform for accumulation‐mode OPECT but also provides a groundbreaking structural and theoretical foundation for bioelectronic detection.