Single-Electrode COF-Based Multiplex Photoelectrochemical Biosensor with Combinatorial DNA Logic Gate for Intelligent Discrimination of Inflammatory Biomarkers.

Simultaneous and accurate detection of interleukin-6 (IL-6) and tumor necrosis factor-alpha (TNF-α) is critical for the early diagnosis and monitoring of inflammatory diseases. However, conventional analytical methods are often cumbersome, time-consuming, and limited in the capacity for simultaneous multiplex analysis and rapid biomarker discrimination. Herein, an integrated multiplex PEC sensing platform is developed for the synchronous, highly sensitive detection and intelligent discrimination of IL-6 and TNF-α. The sensor is constructed by integrating a copper phthalocyanine-based covalent organic framework as the photoactive material with a catalytic hairpin assembly (CHA) cycling amplification strategy. Upon target recognition by specific aptamers, DNA signal strands are released and trigger a CHA reaction on the electrode surface, forming Y-shaped DNA structures and enabling detection in a "signal-off" mode. The sensing system functions as an OR logic gate capable of responding to the presence of either target and distinguishing between individual and coexisting target states through combinatorial logic operations. Different from conventional multiplex sensing strategies that rely on complex instrumentation or multichannel configurations, the approach uses a single electrode for signal readout, offering simple fabrication, rapid response, and low cost. This work provides an effective strategy for multiplex detection of inflammatory markers and highlights the potential of intelligent diagnostic platforms for point-of-care applications.