A dual-response ratiometric fluorescent sensor for oxytetracycline determination in milk and mutton samples

Owing to the adverse effects of oxytetracycline (OTC) residues on human health, it is of great importance to construct a rapid and effective strategy for OTC detection. Herein, we developed a dual-response fluorescence sensing platform based on molybdenum sulfide quantum dots (MoS₂ QDs) and europium ions (Eu³⁺) for ratiometric detection of OTC. The MoS₂ QDs, synthesized through an uncomplicated one-step hydrothermal approach, upon OTC integration into the MoS₂ QDs/Eu³⁺ sensing system, exhibit a significant quenching of blue fluorescence due to the inner filter effect (IFE), simultaneously enhancing the distinct red emission of Eu³⁺ at 624 nm, a phenomenon attributed to the antenna effect (AE). This sensor demonstrates exceptional selectivity and sensitivity towards OTC, characterized by a linear detection range of 0.2-10 μM and a notably low detection limit of 2.21 nM. Furthermore, we achieved a visual semi-quantitative assessment of OTC through the discernible fluorescence color transition from blue to red under a 365 nm ultraviolet lamp. The practical applicability of this sensor was validated through the successful detection of OTC in milk and mutton samples, underscoring its potential as a robust tool for OTC monitoring in foodstuffs to safeguard food safety.