Sensitive and selective detection of tetracycline using fluorescence-enhanced Eu(III)-functionalized silver...

Utilizing metal luminescence enhancement to design fluorescent probes is a very sensible strategy. Herein, a fluorescent probe based on europium (III)-functionalized silver nanoparticles-conjugated homocysteine (AgNPs-Hcy-Eu³⁺) was proposed for the selective and sensitive detection of tetracycline (TC). In this probe, Eu(III) was employed as the detection signal unit for TC, while AgNPs-Hcy was used as the ligand of fluorescence enhancement. When TC exists, it can bind to Eu³⁺ immobilized in AgNPs-Hcy, leading to an enhanced fluorescence signal from Eu³⁺ through energy transfer. Under optimal conditions, the fluorescence intensity of AgNPs-Hcy-Eu³⁺ increased linearly with increasing TC concentration in the range of 0.1-30 μM (R² = 0.9964). The fluorescent probe own fluorescence enhancement, paving the way for sensitive detection with a low detection limit of 0.083 μM. It also has good selectivity for common antibiotics and anions. This work can be applied to the determination of TC in tap water and milk with recoveries of 94-98.5%. We expect AgNPs-Hcy-Eu³⁺ to have potential applications in environmental testing and food safety.