The dual enzyme-like activities (phosphatase-like activity and laccase-like activity) of one nanozyme (Ce-MOF-808) were employed to develop a nanozyme cascade sensor for the facile and selective detection of profenofos. It was found that the nanozyme Ce-MOF-808 had phosphatase-like activity (V max = 0.31 μM/min and K m = 0.014 mM) and laccase-like activity (V max = 6.27 μM/min and K m = 0.033 mM). In the cascade sensor process, profenofos was first hydrolyzed by Ce-MOF-808. The P O bond was cleaved to produce 4-bromo-2-chlorophenol containing phenol through the phosphatase-like activity of nanozyme. The colorless product was efficiently oxidized because of the laccase-like activity of nanozyme, and then reacted with the color rendering agent 4-aminoantipyrine to produce the red quinone imine. The absorbance peak at 510 nm fitted a linear curve. The limit of detection (LOD) was determined to be 3.33 μg/mL in this method. The quantitative detection of profenofos was conducted on a variety of different real samples. Nanozymes could be stored at 4 ℃ for a long time and the detection method was simple and direct. The nanozyme cascade sensor was convenient and rapid for the detection of pesticides and had promising application prospects in the conventional rapid detection of pesticides in the field.
Dangqin Jin,Jiali Xiao,Hui Zhou,Qin Gao,Aiqin Gong,Qin Xu,Yun Shu
An ultra-sensitive photoelectrochemical sensing platform for profenofos detection based on the inhibition of catalase activity was prepared in this work. First, the novel functional nanocomposite material AgVO3/BiOI was prepared by a hot solvent method and successive ion layer adsorption reaction. Then, chitosan was employed as a dispersion medium to disperse and immobilize the catalase. Under visible light irradiation, the prepared CAT/CS/AgVO3/BiOI/ITO nanocomposite electrode generates a stable low photocurrent in hydrogen peroxide solution. When this electrode is immersed in a phosphate buffer solution containing profenofos, the activity of the catalase is inhibited, resulting in an increase in the photocurrent. Under the optimized experimental conditions, the profenofos concentration and increase in photocurrent are linearly related in the concentration range of 1 × 10−10 to 5.0 × 10−8 mol L−1, and the limit of detection is 1.0 × 10−11 mol L−1. This biosensor shows good selectivity for detecting profenofos in fruits and vegetables, and the determination results of profenofos are satisfactory.
As a moderately toxic organophosphorus pesticide, profenofos (PFF) is widely used in agricultural practice, resulting in the accumulation of a high amount of PFF in agricultural products and the environment. This will inevitably damage our health. Therefore, it is important to establish a convenient and sensitive method for the detection of PFF. This paper reports a photoresponsive surface-imprinted polymer based on poly(styrene-co-methyl acrylic acid) (PS-co-PMAA@PSMIPs) for the detection of PFF by using carboxyl-capped polystyrene microspheres (PS-co-PMAA), PFF, 4-((4-(methacryloyloxy)phenyl)diazenyl) benzoic acid, and triethanolamine trimethacrylate as the substrate, template, functional monomer, and cross-linker, respectively. PS-co-PMAA@PSMIP shows good photoresponsive properties in DMSO/H2O (3:1, v/v). Its photoisomerization rate constant exhibits a good linear relationship with PFF concentration in the range of 0~15 μmol/L. PS-co-PMAA@PSMIP was applied for the determination of PFF in spiked tomato and mangosteen with good recoveries ranging in 94.4–102.4%.
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