Abstract
A rapid, sensitive and enzyme-based optical biosensor was applied for the determination of seven organophosphorus pesticides (OPPs), including the oxo forms (malaoxon, paraoxon, dibrom, and dichlorvos), the thio forms (malathion and parathion) and the mixed form (demeton) in Panax ginseng. The principal of the proposed method is that the fluorescence quenching effect of quantum dots (QDs) can be observed by enzyme-generated H2O2. The active centers of acetylcholinesterase (AChE) could be inhibited in the presence of pesticides, which caused decrease of the generated H2O2. Then, the inhibition efficiency of pesticide to AChE activity could be evaluated by measuring the fluorescence changes. Different from biosensors based on immobilized enzyme or self-assembling technique, the proposed biosensor demonstrated a good selectivity for the detection of oxo forms of OPPs. In the present study, the important experimental conditions of the proposed biosensor were investigated. Under the optimized conditions (incubation temperature, 35 °C; incubation time, 20 min; pH value, 8.0; detection time, 30 min; AChE concentration, 40.9 U/L; and choline oxidase (ChOx) concentration, 637.5 U/L), the limit of detection for the investigated oxo-form OPPs was no more than 0.05 μM, which suggested that the proposed method could be used for sensitive and selective determination of trace amounts of OPPs residues in real samples with complex matrices.
Highlights
The past decades have witnessed a significant rise in global agricultural production owing to the boom in human population
A rapid, sensitive and enzyme-based quantum dots (QDs) biosensor has been developed for the detection of organophosphorus pesticides
Since the oxo-form organophosphorus pesticides (OPPs) showed stronger inhibitory effect on AChE activity than the corresponding thio-form OPPs in this study, the proposed method seemed more suitable for the determination of the OPPs with a P=O structure
Summary
The past decades have witnessed a significant rise in global agricultural production owing to the boom in human population. A myriad of pesticides, including organophosphates, organochlorine, carbamates and triazines, have been extensively used to kill or to control unwanted pests, insects or fungi in the process of food and herbal production [1,2]. Much research in recent years has been conducted on the organophosphorus pesticides (OPPs), which are the most commonly used insecticides due to their low cost, high efficiency for insect elimination and faster degradation in the environment [3]. As a representative of the acetylcholinesterase (AChE) activity inhibitors, OPPs could. Many OPPs are the inhibitors of AChE, the OPPs with a P=O structure show the higher toxicity on human or animals than those with P=S structure according to the investigation on the metabolism of pesticides [4,9]
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