Microenvironment-Sensitive Fluorescent Dyes for Recognition of Serum Albumin in Urine and Imaging in Living Cells

A series of microenvironment-sensitive fluorescent dyes, <b>SA1</b>–<b>4</b>, have been presented, which can light up human serum albumin (HSA) in aqueous media and solid state with colorful emissions as well as dramatic fluorescence enhancements respectively, based on twisted intramolecular charge transfer and molecular rotor strategy. These microenvironment-sensitive <b>SA1</b>–<b>4</b> exhibited excellent fluorescent capabilities in the fast, convenient, selective, and sensitive recognition of HSA, especially in the quantitative albumin assay in human urine for assessment of kidney function and diagnosis of renal disease. Moreover, <b>SA1</b>–<b>4</b>/HSA complexes could be applied in fluorescence imaging in living cells

Upconversion Effective Enhancement by Producing Various Coordination Surroundings of Rare-Earth Ions

In this manuscript, we present a simple route to enhance upconversion (UC) emission by producing two different coordination sites of trivalent cations in a matrix material and adjusting crystal field asymmetry by Hf⁴⁺ co-doping. A cubic phase, Y_3.2Al_0.32Yb_0.4Er_0.08F₁₂, with these structural characteristics was synthesized successfully by introducing a small ion (Al³⁺) into YF₃. X-ray diffraction (XRD), nuclear magnetic resonance (NMR), transmission electron microscopy (TEM), X-ray spectroscopy (XPS), and fluorescence spectrophotometry (FS) were employed for its crystalline structure and luminescent property analysis. As a result, the coordination environments of the rare-earth ions were varied more obviously than a hexagonal NaYF₄ matrix with the same Hf⁴⁺ co-doping concentration, with vertical comparison, UC luminescent intensities of cubic Y_3.2Al_0.32Yb_0.4Er_0.08F₁₂ were largely enhanced (∼32–80 times greater than that of different band emissions), while the maximum enhancement of hexagonal NaYF₄ was by a factor of ∼12. According to our experimental results, the mechanism has been demonstrated involving the crystalline structure, crystal field asymmetry, luminescence lifetime, hypersensitive transition, and so on. The study may be helpful for the design and fabrication of high-performance UC materials

Upconversion Effective Enhancement by Producing Various Coordination Surroundings of Rare-Earth Ions

In this manuscript, we present a simple route to enhance upconversion (UC) emission by producing two different coordination sites of trivalent cations in a matrix material and adjusting crystal field asymmetry by Hf⁴⁺ co-doping. A cubic phase, Y_3.2Al_0.32Yb_0.4Er_0.08F₁₂, with these structural characteristics was synthesized successfully by introducing a small ion (Al³⁺) into YF₃. X-ray diffraction (XRD), nuclear magnetic resonance (NMR), transmission electron microscopy (TEM), X-ray spectroscopy (XPS), and fluorescence spectrophotometry (FS) were employed for its crystalline structure and luminescent property analysis. As a result, the coordination environments of the rare-earth ions were varied more obviously than a hexagonal NaYF₄ matrix with the same Hf⁴⁺ co-doping concentration, with vertical comparison, UC luminescent intensities of cubic Y_3.2Al_0.32Yb_0.4Er_0.08F₁₂ were largely enhanced (∼32–80 times greater than that of different band emissions), while the maximum enhancement of hexagonal NaYF₄ was by a factor of ∼12. According to our experimental results, the mechanism has been demonstrated involving the crystalline structure, crystal field asymmetry, luminescence lifetime, hypersensitive transition, and so on. The study may be helpful for the design and fabrication of high-performance UC materials

Confined-Space Mechanism Inspired by the Ingenious Fabrication of a Förster Resonance Energy Transfer System as a Ratiometric Probe for Ag⁺ Recognition

In this work, a facile and interesting fabrication of the Förster resonance energy transfer (FRET) system is presented for the first time by introducing an independent donor and acceptor into a confined space, which is different from the typical “donor–linker–acceptor” FRET system. Human serum albumin (HSA), as a proof-of-concept, is selected to load a pair of spectra-matchable but independent fluorescent dyes (<b>ES1</b> and <b>R1</b>) in its different binding sites. Furthermore, this space-confined FRET system could act as a ratiometric sensor for the quantitative recognition of Ag⁺ in the water samples with good selectivity and high sensitivity