A Photoelectrochemical Aptasensor for Acetamiprid Determination Based on λ Exonuclease-Assisted Recycling Amplification and DNAzyme-Catalyzed Precipitation

Abstract

In the present work, we developed a selective and sensitive photoelectrochemical (PEC) aptasensor for acetamiprid determination. Due to specific recognition ability of the aptamer, acetamiprid could combine with its aptamer, leading to the release of the primer from the aptamer-primer hybrid duplex and the formation of 5′-phosphorylated double-stranded DNAs on the nanocomposite of graphitic carbon nitride and titanium dioxide nanotube array (TNA/g-C3N4), which could be catalytically recycling-digested by λ exonuclease, leading to the amplification of the signal, and the generated DNAzymes could catalyze the in situ production of benzo-4-chlorohexadienone (4-CD) precipitate in the presence of H2O2, causing the significant decrease of photocurrent response of TNA/g-C3N4. Under the optimal experimental conditions, the logarithm of decrease value of photocurrent was linear proportional to the logarithm of acetamiprid concentration from 0.1 pM to 1.0 nM. And the constructed PEC aptasensor exhibited a low limit of detection (0.025 pM) and good selectivity towards acetamiprid determination, which has been successfully applied for the analysis of real vegetable samples with good precision of RSD less than 4.3% and good accuracy of the recoveries ranged from 96.4% to 104.3%.