Organophosphorus pesticides (OPs) can inhibit the activity of acetylcholinesterase (AChE) to induce neurological diseases. It is significant to exploit a rapid and sensitive strategy to monitor OPs. Here, a metal–organic framework (MOF) acted as a carrier to encapsulate AuNCs, which can limit the molecular motion of AuNCs, trigger the aggregation-induced emission (AIE) effect, and exhibit a strong fluorescence with a fluorescence lifetime and quantum yield of 6.83 μs and 4.63%, respectively. Then, the marriage of fluorescence and colorimetric signals was realized on the basis of the dual function of the enzymolysis product from AChE and choline oxidase (CHO) on AuNCs@ZIF-8. First, it can decompose ZIF-8 to weaken the restraint on AuNCs, and thus the fluorescence receded. Second, it can be used as a substrate for the peroxidase mimics of the released AuNCs to oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) and a visible blue appeared. Thus, on the basis of the inhibition of AChE activity by OPs, a fluorescence–colorimetric dual-signal biosensor was established. In addition, colorimetric paper strips were exploited to realize a visual semiquantitative detection, and a smartphone APP was developed to make the visualization results more precise and realize real-time supervision of pesticide contamination.

Immunosensor with photoelectrochemistry and fluorescence responsibility is widely used in biomedical detection, health monitoring, and food safety inspection. The cumbersome configuration and low integration of the current immunosensors, however, have brought challenges for their practical applications. To address these challenges, a portable and phone-APP controlled dual-modular immunosensor based on a bimetallic metal-organic framework (MOF) heterostructured photoelectrode, ZnO/NiZn-MOF/CdS, grafted with an enzyme-mimicking Au@CuO/Cu 2 O label is constructed to achieve simultaneous photoelectrochemistry and fluorescence signage. In the electrode design, the construction of a bimetallic NiZn metal-organic framework (NiZn-MOF) into the common ZnO/CdS photoresponsive structure achieves significant and stable photocurrent output under a very low-power LED light source for not only accelerating the transfer of photogenerated electrons from CdS to ZnO, but also stabilizing the holes of CdS to improve its photocorrosion resistance. After the graft of multifunctional enzyme-mimicking Au@CuO/Cu 2 O label clusters, a portable dual-modular immunosensor is built for the detection of rosiglitazone, a common antidiabetic drug and strictly restricted food residual, over a range from 10 −3 to 1 µg L −1 . This MOF-based immunosensor offers insights into highly sensitive dual-modular responsive material innovations and provides miniaturized biomedical detectors with promising commercialization potentials.

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