Yb-Based Nanoparticles with the Same Excitation and Emission Wavelength for Sensitive in Vivo Biodetection

Encoding Multilayer Complexity in Anti-Counterfeiting Heterometallic MOF-Based Optical Tags

Optical tags provide a way to quickly and unambiguously identify valuable assets. Current tag fluorophore options lack the tunability to allow combined methods of encoding in a single material. Herein we report a design strategy to encode multilayer complexity in a family of heterometallic rare-earth metal-organic frameworks based on highly connected nonanuclear clusters. To impart both intricacy and security, a synergistic approach was implemented resulting in both overt (visible) and covert (near-infrared, NIR) properties, with concomitant multi-emissive spectra and tunable luminescence lifetimes. Tag authentication is validated with a variety of orthogonal detection methodologies. Importantly, the effect induced by subtle compositional changes on intermetallic energy transfer, and thus on the resulting photophysical properties, is demonstrated. This strategy can be widely implemented to create a large library of highly complex, difficult-to-counterfeit optical tags.

Eu3+/Tb3+ supramolecular assembly hybrids for ultrasensitive and ratiometric detection of anthrax spore biomarker in water solution and actual spore samples

Rare earth (RE) complexes have found a variety of applications in materials science and biomedicine because of their unique luminescence properties. However, the poor stability and solubility in water of multicomponent RE assemblies significantly limit their practical applications. We rationally designed and developed a novel Eu³⁺/Tb³⁺ supramolecular assembly hybrids (Eu/Tb-SAH) by supramolecular host-guest recognition and coordination recognition with the excellent characteristics of water dispersion stability, biocompatibility and luminous properties. As anthrax spore biomarker, 2,6-pyridinedicarboxylic acid (DPA) can coordinate with Tb³⁺ and sensitize Tb³⁺, resulting in a proportional change of fluorescence intensity and lifetime on the ms timescales, thereby realizing rapid and sensitive detection of DPA in water media or actual spores. To confirm our prediction, accurate and selective detection of DPA was achieved with Eu/Tb-SAH as a nanoprobe through steady-state ratiometric fluorescence and time-resolved technology, of which the limit of detection (LOD) are 27.3 nM and 1.06 nM, respectively. This was obviously lower than the amount of anthrax spores infecting the human body (60 μM). Besides, the filter paper was used to carry out visual detection of DPA and read the corresponding data through smart phones. This work paves a new way to fabricate luminescent RE nanomaterials and provides new ideas for the design of ratiometic lifetime imaging biosensors in the meantime.

Ultra-Weak Chemiluminescence Enhanced by Cerium-Doped LaF3 Nanoparticles: A Potential Nitrite Analysis Method

In this work, cerium-doped LaF₃ nanoparticles (LaF₃:Ce NPs) were successfully synthesized and characterized. Its chemiluminescence (CL) property was studied, and it was amazingly found that it intensely enhanced the ultra-weak CL of the NaNO₂-H₂O₂ system. The CL mechanism was systematically investigated and suggested to be the recombination of electron-injected and hole-injected LaF₃:Ce NPs. The new CL system was developed to be a facile, original, and direct method for nitrite analysis. Experimental conditions were optimized and then a satisfactory linear relationship between CL intensity and nitrite concentration was obtained. This work introduced a new pathway for the research and application of traditional fluoride NPs doped with RE³⁺.