Portable and real-time detection for tetracycline antibiotics using europium-doped LDH gel intercalated graphene quantum dots.

Tetracyclines (TCs) residues pose a significant threat to the aquatic environment and human health, therefore this study aims to develop a simple, rapid, and sensitive TCs detection method. Herein, a dual-responsive gel probe (LDH-CES@N) was designed, consisting of the intercalation of graphene quantum dots into europium-doped layered double hydroxide (LDH). In the presence of TCs, the as-prepared probe exhibited dual emission fluorescence at 504 nm and 616 nm due to the synergistic effect of aggregation-induced emission and antenna effect. Meanwhile, the density functional theory was employed to validate the mechanism underlying TC-induced electron transfer from graphene quantum dots. The dual-signal response fluorescence probe has excellent detection ability of oxytetracycline, including a wide detection range (0-60 μM), low detection limit (0.145 μM), and rapid response time (120 s). Furthermore, combined with the smartphone, a portable and real-time detection platform was established for the visual detection of oxytetracycline in tap water and honey samples with desirable recovery rates (97.8 %-105.4 %). Therefore, this work provides a new strategy for fluorescence detection of trace pollutants, demonstrating considerable practical application potential.