One-Click Egg Safety Check: A Syringe-Integrated Portable Platform for On-Site Fluoroquinolone Residue Detection

A portable integrated sensing device incorporating a Tb 3+ /DTE-Cu NC ratiometric fluorescent probe was developed for the rapid on-site detection of fluoroquinolone (FQ) residues in poultry eggs. The system features a dual-layer filtration unit, consisting of glass wool and a polyvinyl alcohol/sodium alginate hydrogel, which purifies egg samples in situ through combined physical interception and chemical adsorption. The Tb 3+ /DTE-Cu NC probe was immobilized within the hydrogel matrix, enabling full integration of the entire “sample introduction−filtration−detection” process. Under 365 nm UV light, fluorescence emission shifts from red to green as the FQ concentration increases. Quantitative analysis is accomplished by extracting the G /R ratio from smartphone-captured RGB values. The device achieves a detection limit of 1.6 nM, with recoveries for spiked egg samples ranging from 91% to 112%. This low-cost, rapid, and instrument-free platform presents a practical solution for the sensitive on-site monitoring of antibiotic residues in food safety applications.