Nanozyme biosensors have the potential to provide high sensitivity, multiple functionality, and tunable activity. A facile colorimetric biosensor for the detection of organophosphates (OPs) using cysteamine capped gold nanoparticle probes (C-AuNPs) as enzyme mimics is proposed. Parathion ethyl (PE) a class of OPs is a potent insecticide that functions by inhibiting the acetylcholinesterase (AChE) in the nervous system of insects. The inhibition kinetics of AChE using PE enables the development of a PE sensor. C-AuNPs possess the ability to catalyze the oxidization of 3, 3’, 5, 5’-tetramethylbenzidine (TMB) to a blue-colored product without peroxidase. The detection of PE was monitored by the inability of AChE to generate choline. Choline causes the aggregation of C-AuNPs and the aggregated C-AuNPs has decreased ability to catalyze the oxidization of TMB. A calibration was developed in the 40-320 nM range for the quantitative detection of PE. The limit of detection observed was 20 nM and the method had excellent specificity. The proposed sensor provides an excellent platform for on-site monitoring of PE in environmental and food samples with high sensitivity and greater selectivity.
Colorimetric detection of organophosphates with cysteamine capped gold nanoparticle sensors
