Implementing Defects for Ratiometric Luminescence Thermometry

Nanocomposite Hydrogels as Functional Extracellular Matrices

Over recent years, nano-engineered materials have become an important component of artificial extracellular matrices. On one hand, these materials enable static enhancement of the bulk properties of cell scaffolds, for instance, they can alter mechanical properties or electrical conductivity, in order to better mimic the in vivo cell environment. Yet, many nanomaterials also exhibit dynamic, remotely tunable optical, electrical, magnetic, or acoustic properties, and therefore, can be used to non-invasively deliver localized, dynamic stimuli to cells cultured in artificial ECMs in three dimensions. Vice versa, the same, functional nanomaterials, can also report changing environmental conditions-whether or not, as a result of a dynamically applied stimulus-and as such provide means for wireless, long-term monitoring of the cell status inside the culture. In this review article, we present an overview of the technological advances regarding the incorporation of functional nanomaterials in artificial extracellular matrices, highlighting both passive and dynamically tunable nano-engineered components.

Self-reduction-induced BaMgP2O7:Eu2+/3+: a multi-stimuli-responsive phosphor for X-ray detection, anti-counterfeiting and optical thermometry

Mixed-valence Eu^2+/3+-activated phosphors have attracted wide attention due to their excellent luminescence tunability. Steady control of the Eu²⁺/Eu³⁺ ratio is the key to achieving reproducible Eu^2+/3+ co-doped materials. In this work, BaMgP₂O₇:xEu^2+/3+ (BMPO:Eu, x = 0.001-0.20) was successfully prepared by the traditional solid-state method in air. Eu³⁺ undergoes selective self-reduction at Ba²⁺ sites surrounded by a [P₂O₇] framework, leading to quantitive Eu²⁺/Eu³⁺. The phosphors exhibit a blue-violet emission band at ∼410 nm due to 5d-4f transitions of Eu²⁺ and a group of red emission peaks from ⁵D₀-⁷F_J of Eu³⁺. Controllable multicolor emissions are realized by regulating the Eu content and excitations. A linear response of overall luminescence intensity to irradiation dose makes the phosphor appropriate for X-ray detection. The combination of UV-blue excitation-dependent color evolution and X-ray luminescence qualifies the phosphors with great potential for multi-level anti-counterfeiting. In addition, Eu³⁺ presents abnormal anti-thermal quenching, so that the fluorescence intensity ratio (FIR) of Eu²⁺/Eu³⁺ changes in the temperature range of 300-520 K, suggesting a promising application in optical thermometry. Therefore, selectively partial self-reduction in a multi-cationic host is an effective strategy to design mixed-valence co-doped materials, providing a multiplicity of applications.

Synthesis and luminescence spectroscopy study of a novel orange-red colour emissions phosphor based on Tb3+ ion-doped Na2 ZnP2 O7

Here, we report the synthesis and study of new orange-red (OR) colour-emitting phosphors Na₂ ZnP₂ O₇ :xTb³⁺ (x = 1, 1.25, 1.5, and 1.75 mol%) using a conventional solid-state reaction. The sample crystallographic structures and their room temperature photoluminescence properties were measured using X-ray powder diffraction, excitation and emission spectra, as well as emission decay curves. X-ray diffraction analysis showed an isostructural tetragonal structure for all the doped materials with no impurities. Several colour emissions corresponding to ⁵ D₄ →⁷ F₆ (blue), ⁵ D₄ →⁷ F₅ (green), ⁵ D₄ →⁷ F₄ (orange) and ⁵ D₄ →⁷ F_3,2,0 (red) intraconfigurational transitions were observed and investigated. These colours were dominated by the OR colours. ⁵ D₄ energy level lifetime was independent of Tb³⁺ concentration. Various radiative and luminescence parameters, such as experimental branching ratio, radiative decay rate, and luminescence quantum efficiencies, were calculated and discussed. Chromaticity diagram calculations illustrated an orange emission for all the studied materials.