Electrochemical DNA-Based Sensor for Organophosphorus Pesticides Detection

In this work, we propose an electrochemical DNA-based sensor for sensitive detection of organophosphorus pesticides. To improve the sensitivity of the DNA-based sensor, polyaniline film and gold nanoparticles were progressively electrodeposited on the graphite screen-printed electrode surface by cyclic voltammetry. Gold nanoparticles were then employed as platform for the immobilization of thiol-tethered DNA oligonucleotide sequence complementary to the selected biotinylated DNA aptamer for profenofos detection. Streptavidin-alkaline phosphatase enzyme conjugate was then added to trace the affinity reaction through the hydrolysis of 1-naphthyl phosphate to 1-naphthol, which was then detected by differential pulse voltammetry. A decrease of the signal was obtained when the pesticide concentration was increased, making the sensor work as signal off sensor.