Dual-emission dye@MIL-101(Al) composite as fluorescence sensor for the selective and sensitive detection towards arginine

The application of fluorescence molecules in imaging, sensors, and other fields has attracted extensive attention. However, the inherent problems of aggregation-caused quenching (ACQ) limit the application of fluorescent dyes. Herein, the dual-emission EY@NH2-MOF composite was synthesized by adding fluorescent dye eosin Y (EY) into MIL-101 aluminum-based metal-organic framework (NH2-MOF) through the encapsulation strategy. NH2-MOF can stably bind EY molecules within its cavity and effectively prevent the ACQ behavior of EY molecules. The obtained EY@NH2-MOF composites exhibit dual-emission at 437 nm (blue) and 565 nm (yellow), respectively, and could be acted as a new colorimetric and fluorescence chemical sensor for the detection of arginine, which has higher sensitivity and selectivity than other amino acids derivatives. By using density functional theory (DFT), the fluorescence quenching mechanism of NH2-MOF was further explored. Considering the several hydrogen bonds between the guanidine group and carboxyl group of arginine, it promotes the charge transfer among arginine, NH2-MOF, and EY, and further promotes their energy transfer. In addition, this method can further apply to the sensing of arginine in the milk sample, which suggests the potential application of EY@NH2-MOF in practical analysis.