Abstract：Accurate and rapid detection of pesticide residues in water is crucial to water safety. Based on the current rectification phenomenon of nanochannels, and combined with the characteristics of aptamers that specifically binding to the target, an electrochemical aptamer sensor was constructed to realize the detection of malathion(Mal). The Mal aptamer 1(Apt-1)was modified into the gold-coated nanopipette lumen through gold-sulfur bonds, and the specific binding of Mal to Apt-1 and apta-mer 2(Apt-2)was used to change the interior of the nanochannel. The characteristics of charge density enable the quantitative detection of Mal. Scanning electron microscopy(SEM)and circular dichroism(CD)were used to characterize the nanopipettes and the inside of the nanochannel. The experimental parameters such as the modification concentration of Apt-1, the concentration of Apt-2, and the pH of the incubation solution and the incubation time were optimized. Under the optimum experimental conditions, the logarithm of Mal concentration is linear with the response current signal of the sensor, and linear range of Mal detection range of the sensor is 1.0×10-8-1.0×10-6 mol/L, and the limit of detection(LOD)was 3.33×10-9 mol/L. The stability of the aptamer sensor and the selectivity of Mal detection were investigated. The sensor can be used for the analysis of Mal in water samples, and the results obtained are basically consistent with those obtained by gas chromatography(GC).
