Electrochemical Biosensor Based on Optimized Biocomposite for Organophosphorus and Carbamates Pesticides Detection

Abstract

This paper presents the characterization and optimization of biosensors based on graphite-epoxy which incorporates the enzyme acetylcholinesterase (AChE). By means of advanced electrochemical techniques, such as electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV), the characterization and optimization of graphite-epoxy-AChE biosensors have been performed. In order to obtain sensitive electrodes, the optimal composition of the transducer material (graphite-epoxy-enzyme ratio) was studied. The optimization of the conductive particles distribution inside the biomaterial has allowed an improvement of the electrochemical properties. Optimal composition guarantees improving electrochemical properties required, such as high electron-transfer rate, high signal-to-noise ratio, and suitable sensitivity. The optimal biocomposite composition range was obtained between 16% and 17% of graphite and 0.12% of AChE. The biosensors were applied to the analysis of different pesticides, organophosphorus and carbamates, using indirect measurements based on enzymatic inhibition process. These optimized biosensors present detection limit one order of magnitude lower compared to the standard composition (nonoptimized) and allow achieving concentrations lower than the established ones by the pesticides regulation. Finally, spiked tap water samples with pesticides were analyzed with the optimized biosensors.

Facile and Low-Cost SPE Modification Towards Ultra-Sensitive Organophosphorus and Carbamate Pesticide Detection in Olive Oil

“…Amongst them, electrochemical enzyme-based biosensors are especially suited for field applications since they are easy to manufacture, require low sample volumes (typically in the order of µL), have a short analysis time and have the ability to be integrated into compact and portable analysis devices [ 10 ]. Recently they have been used for the detection of pesticides in several real samples and complex matrices, such as tap water [ 11 ], vegetables [ 12 ], fruits, milk [ 13 ] and olive oil [ 14 ]. Their principle of operation relies on the inhibitory effects different pesticides have on enzymes.…”

A Critical Review for Real-Time Continuous Soil Monitoring: Advantages, Challenges, and Perspectives

“…70 However, the analyte needs certain incubation period (e.g., minutes to hours) to inhibit the activity of the immobilized enzyme, resulting in steadily declining signals over time (e.g., hours). 71 Although the detection of carbamate pesticides demonstrated a good stability by the enzymatic reactions of acetylcholinesterase (AChE), 72 the weak signals (SNR (signal-to-noise) < 3) inhibited the capability of such biosensors to determine low analyte concentrations (<0.05 mg/L) in soil. Thereby, additional effort should be made to develop highly sensitive devices with high SNR ratios (>5) to enhance the accuracy of agrochemical detections.…”

What are the Main Sensor Methods for Quantifying Pesticides in Agricultural Activities? A Review

“…As for the amperometric biosensors, Montes et al described the characterization and optimization of graphite-epoxy-AChE biosensors, which improve the required electrochemical properties, such as a high electron transfer rate, a high signal-to-noise ratio, and adequate sensitivity. The analyzed water samples exhibited an LOD of 0.00025 mg/L for the CBF [46].…”