Abstract
Matrix-derived electroactive interference remains a major analytical challenge for electrochemical aptasensors in complex food samples. We develop a sequential dual-mode aptasensor based on interface regulation for reliable colorimetric screening and electrochemical quantification of acetamiprid. The aptasensor is constructed on a g‑C₃N₄/AuNP-modified electrode by immobilizing complementary DNA (cDNA), which hybridizes with AuPt@FeₓOγ nanozyme-labeled aptamer probes. Upon acetamiprid introduction, target-induced competitive binding drives partial dissociation of the nanozyme probes from the electrode surface. A subsequent PBS rinsing step enables controlled regulation of the sensing interface by removing dissociated probes and coexisting interferents. The released probes are collected for colorimetric screening based on nanozyme-catalyzed TMB oxidation over a concentration range from 10.0 pg mL⁻¹ to 1.0 µg mL⁻¹, followed by electrochemical quantification using the washed electrode over a range from 10.0 fg mL⁻¹ to 1.0 ng mL⁻¹. The limits of detection are 0.073 pg mL⁻¹ for the colorimetric mode and 0.495 fg mL⁻¹ for the electrochemical mode. In this sequential workflow, colorimetric screening offers rapid visual feedback while electrochemical quantification provides sensitive trace-level analysis; the two modes enable mutual signal validation, reducing false-positive and false-negative responses and improving analytical reliability. Satisfactory accuracy and reproducibility are achieved in real food samples, demonstrating that interface-mediated matrix decoupling is an effective strategy for robust aptasensing in complex matrices.