Development of acetylcholinesterase (AChE) biosensor for determination of carbaryl pesticide in Brassica oleracea Var.capitata L. (Cabbage) and Brassica oleracea Var. italica L. (Broccoli)

• Main Author: Samsidar Anwar
• Format: Thesis
• Language: English; English
• Published: 2018
• Subjects: QP501-801 Animal biochemistry
• Online Access: https://eprints.ums.edu.my/id/eprint/38540/1/24%20PAGES.pdf; https://eprints.ums.edu.my/id/eprint/38540/2/FULLTEXT.pdf; https://eprints.ums.edu.my/id/eprint/38540/

Carbary! pesticide widely applied as insecticide to protect crops against pests in agriculture. Overuses of carbaryl are hazardous as it interrupts human central nervous system by causing signal transmission to be impaired. Because of the hazardous effects resulted by the prolonged exposure to the pesticide, rapid detection of pesticide is highly concerned. Various detection techniques have been developed including chromatographic based method, capillary electrophoresis and spectroscopy. Such techniques are provided excellent sensitivity and accuracy but require expensive instrument, competent handler besides takes longer time of process. In this study, a new electrochemical method was developed based on immobilization of acetylcholinesterase (AChE) enzyme via glutaraldehyde (GA) as a cross linking agent onto glassy carbon electrode (GCE) modified by the homogenously dispersed of multi-walled carbon nanotubes (MWCNTs) and gold nanoparticles (AuNPs) in chitosan (CS) for detection of carbaryl pesticide. The combination of all these nanomaterials are provided great platform for the AChE activity due to their excellent electrochemical properties. The morphological characteristics of hybrid nanomaterials were observed by using SEM, EDX and TE M. The electrochemical behaviours showed the current signals increasing in order: bare GCE < CS/GCE < CS/MWCNTs/GCE < CS/MWCNTs/ AuNPs/GCE. The optimal conditions of the developed biosensor were found of pH 7 for Tris-HCI buffer (0.1 M), 20 s for reaction time, 0.1 V/s for scan rate and 6 min for inhibition time. Based on the inhibition of carbaryl on AChE activity, the DPV was detected in the ranges from 0.1 to 8 mg/L. Low detection limit was found of 4. 95 x 10-3 mg/L with good repeatability, reproducibility and storage stability on the carbaryl detection. The determination of carbaryl in real vegetable samples of Brassica oleracea var. L. capitata (Cabbage) and Brassica oleracea var. L. italica (Broccoli) showed good recovery rates between 73. 7 to 102.8% with relative standard deviation less than 7%. Thus, the developed AChE biosensor is showed a rapid and high sensitive tool for determination of carbaryl in vegetable samples.