A novel Eu(III)-based nano-aggregation for ratiometric fluorescence sensing of tetracycline

Tetracycline detection remains an important research topic in the bioenvironmental field today. This paper reports a novel amphiphilic Eu(III) complex DO 3 AC 12 -Eu for single signal and ratiometric fluorescence detection of tetracycline (TC) in aqueous solution. DO 3 AC 12 -Eu can self-assemble micelle-like nano-aggregation in aqueous solution with no fluorescence. After addition of TC, the Eu(III)-based emission was observed for the effective antenna effect from TC to Eu(III) center. In addition, DO 3 AC 12 -Eu can load 4-methylumbelliferone sodium (MU) as a fluorescence reference to form DO 3 AC 12 -Eu/MU co-assembly nano-aggregation with a blue emission at 450 nm. Based on the TC-induced antenna effect and inner filter effect mechanism between TC and MU, DO 3 AC 12 -Eu/MU exhibits a ratiometrically fluorescent response toward TC, with increasing Eu(III)-based emission at 615 nm, and decreasing MU-based emission at 450 nm. Importantly, DO 3 AC 12 -Eu/MU exhibits superior sensitivity and selectivity over DO 3 AC 12 -Eu . The detection limit of DO 3 AC 12 -Eu/MU toward TC is 0.82 nM, far lower than that of DO 3 AC 12 -Eu (9.5 nM). Furthermore, DO 3 AC 12 -Eu/MU assembly has been successfully used for on-site and real-time detection of TC in food samples by using the smartphone-based visualization method and test gel.