Rapid and label-free visual detection of oxytetracycline via aptamer-mediated modulation of graphene oxide/Pt-Pd nanozyme activity

The aim of this study was to develop a colorimetric sensing method using aptamers for the detection of hygromycin, utilising graphene oxide/platinum-palladium composites. This method induces a conformational change in the aptamer, adjusts the adsorption force of the graphene lamellae on the aptamer, and modulates the catalytic performance of the composites, ultimately enabling the visual detection of oxytetracycline (OTC). The results indicated that under optimal detection conditions – specifically, a system pH of 4.4, a reaction time of 5 min and a TMB concentration of 0.5 mM – the concentration of OTC and absorbance exhibited a linear relationship within the range of 0.1 to 0.6 μM, with a limit of detection of 0.01 μM. The recoveries of OTC in real water samples ranged from 94.2% to 103.7% when employing the standard addition method. The experiment demonstrated that the colorimetric sensor possesses good specificity, reproducibility, and visualisation capabilities, providing significant reference value for the quantitative detection of OTC in aqueous environments.