title: Polyacrylic acid-coated cerium oxide nanoparticles: An oxidase mimic applied for colorimetric assay to organophosphorus pesticides.
abstract: It is important and urgent to develop reliable and highly sensitive methods that can provide on-site and rapid detection of extensively used organophosphorus pesticides (OPs) for their neurotoxicity. In this study, we developed a novel colorimetric assay for the detection of OPs based on polyacrylic acid-coated cerium oxide nanoparticles (PAA-CeO2) as an oxidase mimic and OPs as inhibitors to suppress the activity of acetylcholinesterase (AChE). Firstly, highly dispersed PAA-CeO2 was prepared in aqueous solution, which could catalyze the oxidation of TMB to produce a color reaction from colorless to blue. And the enzyme of AChE was used to catalyze the substrate of acetylthiocholine (ATCh) to produce thiocholine (TCh). As a thiol-containing compound with reducibility, TCh can decrease the oxidation of TMB catalyzed by PAA-CeO2. Upon incubated with OPs, the enzymatic activity of AChE was inhibited to produce less TCh, resulting in more TMB catalytically oxidized by PAA-CeO2 to show an increasing blue color. The two representative OPs, dichlorvos and methyl-paraoxon, were tested using our proposed assay. The novel assay showed notable color change in a concentration-dependent manner, and as low as 8.62 ppb dichlorvos and 26.73 ppb methyl-paraoxon can be readily detected. Therefore, taking advantage of such oxidase-like activity of PAA-CeO2, our proposed colorimetric assay can potentially be a screening tool for the precise and rapid evaluation of the neurotoxicity of a wealth of OPs.
authors.affiliation: School of Ecological and Environmental Sciences, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.
authors.forename: Shi-Xiang
authors.initials: SX
authors.lastname: Zhang
authors.affiliation: School of Ecological and Environmental Sciences, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.
authors.forename: Shi-Fan
authors.initials: SF
authors.lastname: Xue
authors.affiliation: School of Ecological and Environmental Sciences, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.
authors.forename: Jingjing
authors.initials: J
authors.lastname: Deng
authors.affiliation: School of Ecological and Environmental Sciences, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China. Electronic address: mzhang@chem.ecnu.edu.cn.
authors.forename: Min
authors.initials: M
authors.lastname: Zhang
authors.affiliation: School of Ecological and Environmental Sciences, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China.
authors.forename: Guoyue
authors.initials: G
authors.lastname: Shi
authors.affiliation: School of Ecological and Environmental Sciences, School of Chemistry and Molecular Engineering, East China Normal University, 500 Dongchuan Road, Shanghai 200241, China. Electronic address: tszhou@des.ecnu.edu.cn.
authors.forename: Tianshu
authors.initials: T
authors.lastname: Zhou
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism; D000180:Acrylic Resins / Q000737:chemistry*; D001560:Benzidines / Q000737:chemistry; D015374:Biosensing Techniques / Q000379:methods; D002563:Cerium / Q000737:chemistry*; D002800:Cholinesterase Inhibitors / Q000032:analysis*; D003124:Colorimetry / Q000379:methods*; D004006:Dichlorvos / Q000032:analysis; D053758:Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D009943:Organophosphorus Compounds / Q000032:analysis*; D010088:Oxidoreductases / Q000737:chemistry; D010261:Paraoxon / Q000031:analogs & derivatives / Q000032:analysis; D010575:Pesticides / Q000032:analysis*
chemical_list: D000180:Acrylic Resins; D001560:Benzidines; D002800:Cholinesterase Inhibitors; D009943:Organophosphorus Compounds; D010575:Pesticides; D002563:Cerium; C021758:3,3',5,5'-tetramethylbenzidine; C006903:carbopol 940; C030583:ceric oxide; D004006:Dichlorvos; D010088:Oxidoreductases; D000110:Acetylcholinesterase; D010261:Paraoxon; C008480:methylparaoxon
keywords: Acetylcholinesterase; Colorimetric assay; Organophosphorus pesticides; Oxidase mimic; PAA-CeO(2)