Development of a europium (III) ion functionalized silica nanoprobe for highly sensitive detection of tetracycline

Tetracycline (TC) is a broad-spectrum antibiotic that has been widely used for numerous infection treatment due to its strong inhibitory effect on pathogenic microorganisms, low toxicity and low-cost. However, the abuse of TC may cause its residues in foods, such as meat and milk. Intake of these TC-contaminated foods could promote bacterial resistance to antibiotics. In this work, we report a simple and low-cost nanoprobe method with high selectivity and sensitivity for TC detection. The nanoprobe was developed by chelating europium (III) ion (Eu³⁺) onto the surface of silica nanoparticles (SiNPs-Eu³⁺). The β-diketone configuration of TC can further coordinate with surface Eu³⁺ steadily, then absorb and transfer the excitation energy to Eu³⁺ via “antenna effect” upon UV light irradiation. The SiNPs-Eu³⁺ nanoprobe was weakly luminescent in buffer solution. In the presence of TC, a strong emission at 615 nm was observed upon the excitation at 390 nm. This SiNPs-Eu³⁺ nanoprobe was featured with a wide linear range (5 nM - 10 µM), high sensitivity (LoD = 1 nM), quick response (30 min), allowing it to be used for TC detection in real-world samples.