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

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.