Engineering conductive covalent-organic frameworks enable highly sensitive and anti-interference molecularly imprinted electrochemical biosensor.

Covalent organic frameworks (COFs) have drawn great interest in electrochemical sensing. However, most are integrated as enrichment units or reaction carriers and are co-modified with metal nanomaterials. Few studies use the single pristine COFs as an electrochemical signal amplifier. Aza-fuzed π-conjugated COFs exhibit exceptional signal enhancement and are an effective electron transport layer for electrochemical sensing applications. In this work, different conductive aza-fuzed π-conjugated COFs were optimized by synthetic engineering. Among them, 2D crystalline COF4 with the highest conductivity (240 % via the bare electrodes) was used to modify the screen printing carbon electrode to construct a portable molecularly imprinted electrochemical biosensor for point-of-care glutathione detection. Compared with the conventional strategy of co-modifing with gold nanoparticles, the single conductive COF4 electrochemical sensor exhibited excellent detection performance and better selectivity for thiol interferents. Conductive COFs combining molecularly imprinted polymer provide a promising strategy for constructing low-cost, easy fabrication and operation, highly sensitive and selective electrochemical biosensors.