Carbamate Insecticide Sensing Based on Acetylcholinesterase/Prussian Blue-Multi-Walled Carbon Nanotubes/Screen-Printed Electrodes

Abstract

Prussian blue (PB)-multi-walled carbon nanotubes (MWCNTs) modified screen-printed electrodes (SPEs) were used to immobilize enzyme acetylcholinesterase (AChE) for carbamate insecticide sensing. The synthesized hybrid PB-MWCNTs had high stability at pH values in the range of 5–10 and presented a porous and homogeneous microenvironment to entrap enzyme molecules. The generated hybrids not only acted as carriers of acetyl cholinesterase, but also promoted electron-transfer reactions because of the synergistic effects between MWCNTs and PB. Under the optimal conditions, the response of the sensor was proportional to acetylthiocholine (ATCh) concentrations ranging from 0.1 mM to 0.6 mM, with a sensitivity of 21.97 µA · mM−1 · cm−2. The sensors were further used to detect pesticides, and the inhibition rate of pirimicarb was proportional to the logarithm of its concentration ranging from 1.0 × 10−6 to 1.0 g · L−1, with a limit of detection (LOD) equal to 5.32 × 10−8 g · L−1. In order to evaluate the performance of the detection system, the sensors were applied to determine pirimicarb in water samples and exhibited high sensitivity and good stability. The detection system is fast, simple for analysis of pirimicarb in environmental samples, and could provide a semi-automated analytical system through further improvement in biosensor arrays.