Development of an amperometric micro-biodetector for pesticide monitoring and detection

An enzyme-based electrochemical biodetection system and its corresponding hand-held prototype were developed to monitor pesticide concentrations. By combining biocatalyzation and electrochemistry, the reaction rate of bioredox was transformed into a current signal. The relationship between pesticide concentration and current inhibition rate could therefore be deduced, and pesticide concentration could be determined from output current signals. Different methods were tried to immobilize enzyme onto the surfaces of platinum electrode and screen-printed carbon electrode (SPE). The best performance was obtained by electropolymerization, which provided sensitivity two times higher than the enzyme under a suspended condition. In order to increase sensitivity, the electron mediator, i.e. Prussian Blue (PB) “KFeIIIFeII(CN)6−” was pre-coated onto the electrode surface and gold nanoparticles were intermingled during enzyme immobilization. The system, therefore, had a detection limit as low as 1 μg/L with a pesticide incubation time of 10 min. Experimental data indicate that pH value, temperature, heavy metal ions and organic solvents exerted influences on sensor performance. Even though the applicable temperature range could be expanded to be 10–40 °C via compensation equations, a proper pretreatment was necessary to eliminate the effect of heavy metal ions, especially for copper ions. This micro-biodetector was successfully applied to determine the pesticide residue in tomato juice, and was proven to be serviceable as a general commodity for household use.