Ultrathin Conductive Bithiazole‐Based Covalent Organic Framework Nanosheets for Highly Efficient Electrochemical Biosensing

Abstract Covalent organic frameworks (COFs) with unique structural merits show substantial potential in the construction of biosensors. However, high‐performance COF‐based biosensors have rarely been reported due to special requirements for electrochemical biosensing. Here, the ultrathin nitrogen and sulfur‐rich bithiazole‐based COF nanosheets (COF‐Bta‐NSs) with the thickness of ≈1.95 nm are developed by using an interfacial perturbation growth strategy, and are further integrated with acetylcholinesterase (AChE) through strong supramolecular interactions to construct a high‐performance biosensor for organophosphorus pesticides (OPs) detection. By virtue of the excellent electrical conductivity and abundant edge unsaturated sites of COF‐Bta‐NSs, such unique biosensors can be used for the detection of various OPs, showing a wide detection range, ultralow detection limit, and high stability. Significantly, the portable biosensing device is further set up based on commercialized screen‐printed electrode (SPE), which is sensitive and reliable with the actual samples collected from river water and leafy vegetables, confirming the practical applicability. This research provides a novel insight into the development of advanced COF‐based biosensors with excellent performance for biological and environmental analysis.