A solid-phase capture probe based on upconvertion nanoparticles and inner filter effect for the determination of ampicillin in food

Ampicillin (AMP) is commonly used to treat diseases caused by bacterial infections as a veterinary drug. However, the abuse of AMP can lead to residues in food and ultimately cause harm to humans. Thus, it is significant to construct a reliable system for AMP detection. Here, we developed an inner filter effect system based on a solid-phase capture probe and the catalysis of platinum nanoparticles (PtNPs) for AMP determination in food. In the presence of AMP, PDMS captured AMP then combined with aptamer-functionalized PtNPs, which catalyzed the oxidation of 3,3′,5,5′-tetramethylbenzidine, resulting in upconversion fluorescence quenching. The results showed the fluorescence intensity of upconversion nanoparticles was related to AMP concentration (0.5–100 ng·mL−1) with an LOD of 0.32 ng·mL−1, which made quantification of AMP possible. The method also achieved a satisfactory recovery rate (96.89–112.92%) and can be used for AMP detection in food samples with selectivity and sensitivity.