Self-validating DPV/EIS Dual-Mode Aptasensor Based on Ferrocene-Embedded Zeolitic Imidazolate Framework-67@Pt Nanoparticles for Reliable Chloramphenicol Monitoring

Abstract Sensitive and reliable analysis of chloramphenicol (CAP) residues is essential for ensuring food safety. By combining differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS), this work presents a single-device dual-mode aptasensor based on ferrocene-embedded zeolitic imidazolate framework-67 supported Pt nanoparticles (Fc@ZIF-67@PtNPs) for reliable detection of CAP. The Fc@ZIF-67@PtNP composite was fabricated through a mild self-assembly route and serves as a bifunctional substrate, in which the encapsulated Fc acts as an electroactive species to generate stable redox responses, while Pt NPs boost electrical conductivity and allow aptamer immobilization through Pt–N bonds for specific CAP recognition. Upon binding with CAP, the generation of an aptamer–CAP complex on the electrode surface creates significant steric hindrance, which weakens the Fc oxidation current (IFc) and raises the electron transfer resistance (Ret). Such a dual-mode sensing strategy with a single device enables mutual cross-verification of DPV and EIS results, thus effectively improving detection efficiency, accuracy, and anti-interference reliability. The fabricated aptasensor displays a wide linear response from 0.1 to 1000 ng mL–1 in both DPV and EIS modes, with LODs of 10.2 and 60.7 pg mL–1, as well as favorable selectivity, reproducibility, and stability. It also performs well in milk, egg, and water samples, showing promising application potential in practical CAP residue analysis.