Development of a rapid and simple tetracycline detection system based on metal-enhanced fluorescence by europium-doped AgNP@SiO(2) core–shell nanoparticles

We herein describe a rapid and selective sensing platform for tetracycline (Tc), which relies on the metal-enhanced fluorescence (MEF) effect of europium (Eu(3+))-doped silver-silica core–shell nanoparticles (AgNP@SiO(2)). The developed assay utilizes AgNP@SiO(2) as a key detection component, which is systematically optimized to have a silica shell thickness suitable for the effective MEF phenomenon. In principle, the AgNP@SiO(2), which binds to Eu(3+) through the electrostatic interaction, captures Tc by selective chelation with Eu(3+), leading to significant fluorescence enhancement of the EuTc complex. Based on this novel strategy, we determined Tc as low as 83.1 nM with a total assay time of less than 10 min, which is comparable to or better than that of the previous fluorescence-based methods. Furthermore, the practical applicability of this strategy was successfully demonstrated by detecting Tc in tap water. This work highlights the unique features of AgNP@SiO(2) for MEF-based biosensing applications.