Simultaneous detection of tetracycline and kanamycin by electrochemical sensors based on dual-signal probes Au/Mn-based Prussian blue analogs and methylene blue-functionalized AuPt NFs

Dual-signal probes Au/Mn-based Prussian blue analogs (Mn-PBA) and methylene blue (MB)-functionalized AuPt nanoflowers (AuPt NFs) were prepared, and an electrochemical aptasensor capable of simultaneously detecting tetracycline (TET) and kanamycin (Kana) was constructed using exonuclease III (Exo III)-assisted cycling. The combination of Mn-PBA and Au NPs resulted in Au/Mn-PBA, which exhibits high redox properties and can provide electrochemical signals for target detection. MB-modified AuPt NFs were used as another signaling probe. Their flower-like structure loads a large number of signaling molecules to provide electrochemical signals to the sensor. Magnetic beads were used to connect different DNA sequences, enabling simultaneous Exo III cycling of the supernatant and precipitate in the presence of target analytes. Under the optimal conditions, the linear range of TET and Kana was 0.001–500 ng mL⁻¹ . The limit of detection (LOD) of TET was 0.126 pg mL⁻¹ , and that of Kana was 0.933 pg mL⁻¹ . The limits of quantification (LOQs) of TET and Kana were 0.912 pg mL⁻¹ and 3.31 pg mL⁻¹ , respectively. In addition, the sensor successfully achieved simultaneous detection of TET and Kana in real samples, showing promising practical prospects.