Integrating Intelligent Logic Gate Dual-Nanozyme Cascade Fluorescence Capillary Imprinted Sensors for Ultrasensitive Simultaneous Detection of 2,4-Dichlorophenoxyacetic Acid and 2,4-Dichlorophenol

Herein, a dual-nanozyme cascade catalysis triemission fluorescence capillary imprinted sensor integrated with intelligent logic gates was constructed for simultaneous detection of 2,4-dichlorophenoxyacetic acid (2,4-DA) and 2,4-dichlorophenol (2,4-DCP). The novel nanozyme fluorescence organic framework (Bi, Co-MOF) was grafted on the surface of Fe3O4 modified with histidine to form a nanozyme composite (FBM) with dual-enzyme activity, which was imprinted with 2,4-DA to prepare a fluorescence molecularly imprinted polymer (FBM@MIP). Carbon dots (CDs) coupling with FBM@MIP (FBM@MIP/CDs) was inhaled into a capillary to construct a dual-nanozyme capillary imprinted sensor directly. The FBM@MIP/CDs capillary sensor realized to detect 2,4-DA and 2,4-DCP simultaneously within a linear concentration range of 1.0 × 10–12–1.2 × 10–9 M and 1.0 × 10–12–4.8 × 10–9 M with the detection limit of 0.75 and 0.68 pM, respectively. Interestingly, a smartphone-assisted portable capillary fluorescence intelligent sensing platform was developed that can detect 2,4-DA and 2,4-DCP visually without tedious operations such as soaking and drying. Combined with a smartphone, the linear relationships between RGB ratios and concentrations of 2,4-DA and 2,4-DCP were established with the detection limit of 0.93 and 0.81 pM, respectively. The integrated logic gates provided a promising way for intelligent sensing of multiple targets simultaneously, which provided a new strategy for ultrasensitive simultaneous detection of multiple pollutants with a microvolume (18 μL/time) in complex environments.