Thermal-controlled active sensor module using enzyme-regulated UiO-66-NH2/MnO2 fluorescence probe for total organophosphorus pesticide determination.

An enzyme-regulated UiO-66-NH2/MnO2 fluorescence sensor, fully functionalized with spectrometric capacities, is developed for budget-friendly total organophosphorus pesticides (OPs) determination. The fluorescence probe, UiO-66-NH2/MnO2, is hydrothermally synthesized and morphologically examined. A specialized enzyme-catalyzed reaction, which can be gradually inhibited by OPs, is designed with participations of alkaline phosphatase (ALP) and sodium L-ascorbyl-2-phosphate (AAP). The reaction product of ascorbic acid (AA) decomposes MnO2 and restores UiO-66-NH2 fluorescence, establishing a relationship between OPs level and fluorescence intensity. Interactions among UiO-66-NH2, MnO2, OPs, and AA are clarified. Stepwise optimizations are performed to the UiO-66-NH2/MnO2 probe, ensuring considerable advantages as OPs affinity and fluorescence quenching behavior over rival nanomaterials. Analytical advances are magnified by fabricating an active sensor module, with self-acting thermal regulation for optimal enzyme activity. Under 4 and 20 °C environment, regulation period is less than 40 and 100 s. In total OPs determination for laboratorial and real-vegetable samples, this method exhibits uniform and log-linear responses to common species of OPs in a range as 1.0 × 10-7~10 mg L-1, and limit of detection is established as 8.9 × 10-8 mg L-1. Proposed readouts are validated with certified HPLC and recovery test. Relative errors and recovery rates are found as 2.7-6.4% and 95.8-102.6%, respectively.