Dopamine and arginine are both important substances in the body and are closely related to human health. Timely detection of their concentration abnormalities is of great significance to the prevention of disease. In this work, a Tb³⁺-functionalized Eu-MOF hybridized double network hydrogel film (Tb@Eu-MOF@PVA/SA) was prepared by a simple synthesis, which can accurately detect arginine (Arg) and dopamine hydrochloride (DH). Meanwhile, the hydrogel acquired good mechanical properties through crosslinking of Tb³⁺and freeze–thaw cycles. The free carboxyl groups on the surface of the Eu-MOF in this hydrogel film can bind to Tb³⁺ and sensitize it to emit light through the “antenna effect”, thus forming a fluorescent hydrogel film with dual emission centers. By testing two kinds of detectors and controlling different excitation wavelengths, we can realize the encryption and decryption of information and build an anti-counterfeiting platform to improve the level of information security. The present work not only provides a case study for the preparation of dual-emission Tb³⁺-functionalized Eu-MOF hybridized dual-network hydrogel films, but also provides ideas for the development of multifunctional luminescent materials.

Globally, antibiotic abuse, organic contamination, and excessive heavy metal ion pollution pose serious threats to human health. In this case, ratiometric fluorescent probes can eliminate the errors caused by environmental factors and provide more accurate detection results than single-emission intensity nanoprobes. Accordingly, based on the excellent biocompatibility and abundant surface functional groups of carbon quantum dots (CQDs) and the properties of large Stokes shifts and narrow emission bands of rare earth ions (RE³⁺), RE-CQD fluorescent probes have attracted widespread attention. Herein, firstly we review the combination of carbon quantum dots with rare earth ions (rare earth complexes) using various functionalization approaches to improve the defects of rare earth complexes and realize the functionalization of carbon quantum dots and their applications in many fields, such as biology and environmental science. In addition, we classify the methods for the synthesis of RE-CQD hybrids into three groups according to the different binding modes of the RE and CQDs, including doping, covalent grafting, and direct coordination. The excellent properties of these fluorescent probes are also briefly described. Finally, a comprehensive overview of the important applications of RE-CQD fluorescent probes in the fields of public safety sensing, chemical sensing, biomedical sensing, temperature sensing, and pH sensing is presented. In this review, the recent research progress in the field of ratiometric fluorescence sensing based on carbon quantum dots and rare earth ions is summarized and an outlook on the future development of RE-CQD fluorescent probes regarding their construction and potential applications is provided.