Liu_2026_Mikrochim.Acta_193_

A complementary dual-mode biosensor was constructed for determination of chlorpyrifos (CP) using a multifunctional composite consisting of MnO(2)@thionine/ZIF-8 (MnO(2)@Thi/ZIF-8). This composite synergistically combines the good oxidase-mimetic activity of MnO(2) dispersed on the surface of ZIF-8 with the stable electroactivity of thionine (Thi) encapsulated within detachable ZIF-8 framework, enabling dual-mode detection of CP. In the presence of acetylcholinesterase (AChE) and its substrate acetylthiocholine (ATCh), enzymatic hydrolysis quantitatively produces acetic acid (HAc) and thiocholine (TCh). TCh acts as a reducing agent to convert MnO(2) to Mn(2+), leading to diminished oxidase-mimetic activity of MnO and a subsequent decrease in the oxidation of 3,3',5,5'-tetramethylbenzidine (TMB) to oxidized TMB (oxTMB). Concurrently, HAc induces the hydrolysis of ZIF-8, resulting in the release of encapsulated Thi, generating electrochemical current. Upon CP addition, AChE activity is selectively inhibited, reducing the production of both TCh and HAc. The complementary dual-mode sensor exhibits good analytical results (electrochemical mode: 0.1-60 ng/mL; colorimetric mode: 0.5-60 ng/mL) and satisfactory performance in real-sample analysis. This study not only provides an effective strategy for sensitive and accurate monitoring of OPs through the synergistic integration of inorganic oxides with metal-organic frameworks (MOFs) but also offers new insights into the design of multifunctional nanozymes for multimodal sensing platforms.