Liu Yaqing,Lin Xiaodong,Ji Xiangyi,Hao Zhe,Tao Zhanhui
A novel fluorescence strategy based on the outstanding catalytic capability of CuS nanoparticles (CuS NPs ) has been developed for highly sensitive and specific determination of o,o-dimethyl-o-2,2-dichlorovinyl phosphate (DDVP) under enzyme-free and hydrogen peroxide (H 2 O 2 )-free conditions. In the presence of DDVP, CuS NPs can catalyze non-fluorescence substratum of Amplex red (AR) into resorufin, which exhibits fluorescence emission at 584 nm under excitation at 540 nm. The sensing system exhibits outstanding specificity and only responds to DDVP and no other organophosphorus pesticides (OPs). A wide linear range is obtained from 0.0001 to 0.1 μg/mL, and the limit of detection (LOD) is 0.1 ng/mL. Furthermore, paper-based test strips have been constructed for visual detection of DDVP under ultraviolet light irradiation. By integrating a smartphone installed with Color Picker APP, point-of-care detection with quantitative determination is realized, demonstrating substantial potential applications of the as-developed assay for in situ detection.
Graphical abstract
Alkaline phosphatase (ALP), as an essential disease biomarker, widely distributes in various tissues, and plays a significant role in diagnosis and treatment of some diseases (e.g. cancers and liver dysfunction). Dichlorvos (DDVP), as one of typical organophosphate pesticide , could be hydrolyzed by ALP. In this work, we constructed a simple but robust 4-cyano-4′-pentylbiphenyl (5CB) droplet sensing platform for sensitive and convenient detection of DDVP based on its hydrolysis by ALP. The optical responses of liquid crystals (LCs) originated from controlling orientations of 5CB by using an ALP cleavable surfactant, sodium monododecyl phosphate (SMP). A dark crossed optical image of 5CB was observed due to formation of the SMP monolayer at the aqueous/LC droplet interface. Subsequently, 5CB turned to bright fan-shaped optical appearance upon addition of ALP and SMP mixture. Interestingly, LCs remained dark crossed optical images in contact with the pre-incubated mixture of DDVP and ALP. The detection limit of DDVP reached ~0.1 ng/mL. Isothermal titration calorimetry (ITC) and humam ALP ELISA kit provided strong evidence for the detection mechanism. This strategy was also used to evaluate whether the maximum pesticide residue limits of tomatoes conform to the relevant national standard requirement or not. Our study holds promise for real-time and label-free detection of pesticides with high sensitivity by employing portable LC-based sensing platform.
危险品化学品经营许可证（带存储）