Electroanalytical platform for nereistoxin-related insecticides detection based on DNA conformational switching and exonuclease III assisted target recycling
In this work, an electroanalytical platform for nereistoxin (NRT)-related insecticides detection is proposed on the basis of NRT induced DNA conformational switching and exonuclease III (Exo III) assisted target recycling. NRT-related insecticides were first hydrolyzed and converted into NRT with two thiol groups (-SH). And then, cytosine-Ag+-cytosine (C-Ag+-C) mismatch was adopted to induce a blunt-ended hairpin configuration of HP DNA. In the presence of converted NRT, it could uptake Ag+ from HP to change its conformation from a hairpin to single-stranded structure (HP ssDNA). Thereafter, the obtained HP ssDNA was further hybridized with H1 hairpin probe on the electrode surface to trigger the Exo III cleavage process, releasing HP ssDNA for recycling and left the G-quadruplex fragment of H1, which was used for hemin/G-quadruplex complex formation. The reversible redox of Fe(III)/Fe(II) of hemin gave a remarkable electrochemical response for quantitative determination of the NRT-related insecticides. As an analytical model, a low detection limit of 3.9 ng/L and wide linear range of 0.01-1500 μg/L with excellent selectivity was achieved for cartap detection. The proposed method also displayed great applicability for cartap detection in agricultural products.