An enhanced fluorescent probe through the strategy of using MgWO4 nanosheets to enhance terbium ion luminescence for highly sensitive and point-of-care visual quantitative testing of ciprofloxacin integrated with a low-cost smartphone-based platform.

In this work, MgWO4 nanosheets have been successfully synthesized by a simple hydrothermal method, and the morphology and composition of the MgWO4 nanosheets are characterized by SEM, TEM, XPS, and UV-vis. The results show that the as-prepared MgWO4 nanosheets have a triclinic symmetry phase and an obvious two-dimensional layered structure. Studies have shown that the MgWO4 semiconductor nanosheets can adjust the energy level, which significantly enhances the visible light absorption and the separation and transfer of photogenerated electrons, which facilitates the generation of photogenerated electrons. We use this feature to boost a terbium ion (Tb3+)-ciprofloxacin (CIP) system to enhance the luminescence, so as to achieve highly sensitive detection of CIP. The mechanism of Tb3+-MgWO4 for CIP detection is the effective energy transfer from WO42- in MgWO4 nanosheets to Tb3+-CIP, thereby enhancing the characteristic emission of Tb3+ and enhancing the sensitivity of CIP detection. The linear response of the Tb3+-MgWO4 enhanced fluorescent probe is in the range from 10 nM to 20 μM, and the detection limit (LOD) is 2 nM. In addition, we tested the recovery in spiked river water and mouse serum. Experiments have shown that the recovery of spiked samples is 97-102.2%, while the relative standard deviation (RSD) is less than 5.53%. The possible interfering substances in environmental samples will not interfere with the detection of CIP with the Tb3+-MgWO4 enhanced fluorescent probe. At the same time, the development of a smartphone-based portable device provides the possibility of CIP on-site detection. Our work provides a simple, fast, highly sensitive and stable method for detecting CIP in living organisms and the environment. Importantly, the strategy of MgWO4 nanosheet boosted terbium ion luminescence expands the application range of semiconductor nanomaterials.