Microwave-assisted sensing of tetracycline using europium-sensitized luminescence fibers as probes

In this paper, we describe a facile approach-using silicate fibers immobilized with Eu(III) ions [Eu(III) fibers] as affinity probes-to rapidly sense tetracycline (TC) in complex samples. The fabrication of the Eu(III) fibers is straightforward: Simply immerse a silicate fiber into a glass tube containing Eu(III) and irradiate with microwaves (power, 900 W) for 30 s. The Eu(III) fibers selectively trap TC from aqueous samples via chelation of the beta-diketone functional group of TC with the Eu(III) center. Because the Eu(III)-TC complexes on the fibers are luminescent, as a result of intermolecular energy transfer from the TC moieties to the Eu(III) centers, they can be detected directly using a fluorophotometer. To accelerate the sensing process, we also used microwave irradiation (for only 15 s) to trap the TC molecules from the sample solutions onto the Eu(III) fibers. Furthermore, only a small volume (< 10 mu L) of sample solution is required for these analyses. This approach allows TC to be detected in aqueous samples, with a detection limit of 50 nM.