Construction of fluorescent aptasensor based on graphene oxide for the detection of metronidazole in food

Aiming at the detection of metronidazole (MNZ) residues in food, a high sensitivity fluorescent aptasensor was designed, which carboxyfluorescein (FAM)-labeled nucleic acid aptamer (FAM-MNZ) as the core probe and graphene oxide (GO) as an efficient fluorescence quencher. Under optimized conditions, milk samples can be accurately detect with a detection limit of 0.033 μM. In addition, molecular docking, lumo electron orbital simulations, and experimental methods were used to explore the effect of different average radial sizes of single-layer GO on sensing performance. It is shown that GO with a larger average size makes it easy for aptamers to be regularly arranged on its surface, which also provides a basis for electron transfer, resulting in higher fluorescence quenching ability through the energy resonance transfer (FERT) mechanism. Therefore, the constructed fluorescent aptamer sensor has a significant application value in food detection. In conclusion, a sensor based on Go fluorescent aptamer was constructed on the principle that graphene oxide can quench the fluorescence of the modified aptamer through the energy resonance transfer (FERT) mechanism. The sensor constructed using GO with an average radial size of 8–10 μm has high sensitivity and specificity, and its detection limit can reach 0.033 μM. It is found that the large-sized GO is easy for aptamers to be regularly arranged on its surface, which adsorbs more aptamers and provides a basis for the electron transfer on its surface. Notably, the size of the nanomaterial plays a crucial role in the construction of the sensor. Finally, the sensor not only shows excellent performance in anti-interference ability and detection of real samples in complex substrates, but also shows great application potential and broad prospect in the field of drug residue detection with its simple operation process and fast detection speed. Its high efficiency and accuracy provide strong technical support for food safety, environmental monitoring and other fields. [Display omitted] •Graphene oxide fluorescent sensor constructed to detect MNZ.•Different sizes of GO on the fluorescence quenching mechanism was investigated.•Computer simulation were used to explore the fluorescence quenching mechanism. Aiming at the detection of metronidazole (MNZ) residues in food, a high sensitivity fluorescent aptasensor was designed, which carboxyfluorescein (FAM)-labeled nucleic acid aptamer (FAM-MNZ) as the core probe and graphene oxi