Electrochemical biosensors based on conducting polymer composite and PAMAM dendrimer for the ultrasensitive detection of acetamiprid in vegetables

The cumulative harm caused by pesticide residues to environmental safety and human health is enormous, and the sensitive and selective detection pesticide in very trace amounts is currently a challenge. Herein, the bio-sensors for the ultrasensitive detection of acetamiprid (ACE) were proposed. The conducting polymer composite of phaseoloidin doped poly(3,4-ethyloxythiophene) (PL/PEDOT) was prepared with high surface area, excellent conductivity and stability, which was followed by the functionalization with poly(amidoamine) of the third generation (PAMAM). ACE aptamers were immobilized onto the platforms (PL/PEDOT and PAMAM/PL/PEDOT) for the development of ACE aptasensors. The concentration of ACE can be measured through both the increase of differential pulse voltammetry (DPV) signal change and the increase of the chronoamperometry (CA) signal change from the reduction of hydrogen peroxide catalyzed by PL/PEDOT. The ACE aptasensor based on PAMAM/PL/PEDOT exhibited linear ranges of 0.1 pg mL-1-10 ng mL-1 and 0.1 fg-1.0 pg mL-1, the detection limits as low as 0.0117 pg mL-1 and 0.0355 fg mL-1 (S/N = 3) through DPV and CA, respectively. Significantly, the response sensitivity of DNA/PAMAM/PL/PEDOT/GCE was 3.11 times higher than that of DNA/PL/PEDOT/ GCE (by CA mode), proving that the PAMAM dendrimer can greatly enhance the sensing performance.