Enhanced quenching efficiency of UiO-66-NH2 over UiO-66 to engineer high-performance fluorescence aptasensor for oxytetracycline monitoring.

Oxytetracycline (OTC), a broad class of antibacterial medication, has been widely utilized in poultry husbandry and fish farming. However, the presence of OTC residues in the food has become a matter of great concern. These residues have the potential to induce the emergence and spread of bacterial resistance, which can have far-reaching consequences for public health. In this work, we focused on the comparison of the quenching efficiency of UiO-66 and its amino group-modified counterpart UiO-66-NH2, towards the fluorescence of nitrogen-doped graphene quantum dots (NGQDs) labeled aptamer (NGQDs-apt). It was found that UiO-66-NH2 demonstrated a more potent fluorescence quenching ability towards NGQDs-apt, as high as 98.8 %, compared to 69.7 % for UiO-66 without amino functionalization. This enhanced performance is attributed to the improved interaction between the amino groups on UiO-66-NH2 and the NGQDs-apt, facilitating more effective electron transfer. Consequently, UiO-66-NH2 was selected as the optimal quencher for the development of a highly sensitive aptasensor. This aptasensor demonstrates a quantitative detection range for OTC spanning from 0.001 to 200 μM with an exceptionally low detection limit of 0.25 nM, showing simplicity, accuracy, stability and great potential for antibiotic residue detection in food samples. This work addresses the urgent need to develop reliable methods for detecting OTC residues in food due to the potential of OTC to trigger bacterial resistance, which is crucial for food safety and public health.