7 research outputs found
Broadband NIR photon upconversion generates NIR persistent luminescence for bioimaging
Upconversion persistent luminescence (UCPL) phosphors that can be directly
charged by near-infrared (NIR) light have gained considerable attention due to
their promising applications ranging from photonics to biomedicine. However,
current lanthanide-based UCPL phosphors show small absorption cross-sections
and low upconversion charging efficiency. The development of UCPL phosphors
faces challenges of lacking flexible upconversion charging pathways and poor
design flexibility. Herein, we discovered a new lattice defect-mediated
broadband photon upconversion process and the accompanied NIR-to-NIR UCPL in
Cr-doped zinc gallate nanoparticles. The zinc gallate nanoparticles can be
directly activated by broadband NIR light in the 700-1000 nm range to produce
persistent luminescence at about 700 nm, which is also readily enhanced by
rationally tailoring the lattice defects in the phosphors. This proposed UCPL
phosphors achieved a signal-to-background ratio of over 200 in bioimaging by
efficiently avoiding interference from autofluorescence and light scattering.
Our findings reported the lattice defect-mediated photon upconversion for the
first time, which significantly expanded the horizons for the flexible design
of NIR-to-NIR UCPL phosphors toward broad applications
Rheological properties of oil–water Pickering emulsion stabilized by Fe3O4 solid nanoparticles
Pickering emulsions have attracted extensive attention due to their good properties including easy to manufacture, high stability, and superparamagnetic response. To improve the emulsifying transportation of crude oil, a Pickering emulsion of crude oil and water stabilized by Fe3O4 nanoparticles was prepared and its rheological properties were tested in this research. It was found that the particle size of dispersion droplet polymerization group in stable crude oil Pickering emulsion is negatively correlated with solid content and water content, and the equilibrium apparent viscosity μap{\mu }_{\text{ap}} of emulsion follows the power law fluid equation. Besides, this kind of Pickering emulsion has higher elasticity of interface membrane, which means by adding functional particles, it obtains good dynamic stability, and thus, has a great application property in crude oil industry
Studies on the spray dried lactose as carrier for dry powder inhalation
The purpose of this study was to investigate the spray dried lactose as carrier for dry powder inhalation (DPI). The lactose particles were prepared by spray drying, then the particle size, shape and crystal form were characterized by laser diffraction, scanning electron microscopy (SEM), X-ray diffraction (XRD) and differential scanning calorimetry (DSC). The spray dried lactose particles were spherical and amorphous, but would transfer to crystal form when storage humidity was above 32%. Thus, the humidity of the storage environment should be controlled below 30% strictly in order to maintain the amorphous nature of spray dried lactose which is a great benefit to DPI development
Abnormally Long-Range Diamagnetic Anisotropy Induced by Cyclic d<sub>δ</sub>–p<sub>π</sub> π Conjugation within a Six-Membered Dimolybdenum/Chalcogen Ring
Incorporating two quadruply bonded dimolybdenum units
[Mo<sub>2</sub>(DAniF)<sub><sup>3</sup></sub>]<sup>+</sup> (ancillary
ligand DAniF
= <i>N</i>,<i>N</i>′-di-<i>p</i>-anisylformamidinate) with two hydroselenides (SeH<sup>–</sup>) gave rise to [Mo<sub>2</sub>(DAniF)<sub>3</sub>]<sub>2</sub>(μ-SeH)<sub>2</sub> (<b>1</b>). With the molecular scaffold remaining unchanged,
aerobic oxidation of <b>1</b>, followed by autodeprotonation,
generated [Mo<sub>2</sub>(DAniF)<sub>3</sub>]<sub>2</sub>(μ-Se)<sub>2</sub> (<b>2</b>). The two complexes share a common cyclic
six-membered Mo<sub>2</sub>/Se core, but compound <b>2</b> is
distinct from <b>1</b> by having structural, electronic, and
magnetic properties that correspond with aromaticity. Importantly,
the aromatic behaviors for this non-carbon system are ascribable to
the bonding analogy between the δ component in a Mo–Mo
quadruple bond and the π component in a C–C double bond.
Cyclic π delocalization via d<sub>δ</sub>–p<sub>π</sub> conjugation within the central unit, which involves
six π electrons with one electron from each of the Mo<sub>2</sub> units and two electrons from each of the bridging atoms, has been
confirmed in a previous work on the oxygen- and sulfur-bridged analogues
(Fang, W.; et al. <i>Chem.Eur. J.</i> <b>2011</b>, <i>17</i>, 10288). Of the three members in this family,
compound <b>2</b> exhibits an enhanced aromaticity because of
the selenium bridges. The remote in-plane and out-of-plane <i>methine</i> (ArNC<i>H</i>NAr) protons resonate at
chemical shifts (δ) 9.42 and 7.84 ppm, respectively. This NMR
displacement, Δδ = 1.58 ppm, is larger than that for the
oxygen-bridged (1.30 ppm) and sulfur-bridged (1.49 ppm) derivatives.
The abnormally long-range shielding effects and the large diamagnetic
anisotropy for this complex system can be rationalized by the induced
ring currents circulating the Mo<sub>2</sub>/chalcogen core. By employment
of the McConnell equation {Δσ = Δχ[(l –
3 cos 2θ)/3<i>R</i><sup>3</sup><i>N</i>]},
the magnetic anisotropy (Δχ = χ<sub>⊥</sub> – χ<sub>||</sub>) is estimated to be −414 ppm
cgs, which is dramatically larger than −62.9 ppm cgs for benzene,
the paradigm of aromaticity. In addition, it is found that the magnitude
of Δχ is linearly related to the radius of the bridging
atoms, with the selenium analogue having the largest value. This aromaticity
sequence is in agreement with that for the chalcogen-containing aromatic
family, e.g., furan < thiophene < selenophene
Broadband NIR photon upconversion generates NIR persistent luminescence for bioimaging
Upconversion persistent luminescence (UCPL) phosphors that can be directly charged by near-infrared (NIR) light have gained considerable attention due to their promising applications ranging from photonics to biomedicine. However, current lanthanide-based UCPL phosphors show small absorption cross-sections and low upconversion charging efficiency. The development of UCPL phosphors faces challenges of lacking flexible upconversion charging pathways and poor design flexibility. Herein, we discovered a new lattice defect-mediated broadband photon upconversion process and the accompanied NIR-to-NIR UCPL in Cr-doped zinc gallate nanoparticles. The zinc gallate nanoparticles can be directly activated by broadband NIR light in the 700-1000 nm range to produce persistent luminescence at about 700 nm, which is also readily enhanced by rationally tailoring the lattice defects in the phosphors. This proposed UCPL phosphors achieved a signal-to-background ratio of over 200 in bioimaging by efficiently avoiding interference from autofluorescence and light scattering. Our findings reported the lattice defect-mediated photon upconversion for the first time, which significantly expanded the horizons for the flexible design of NIR-to-NIR UCPL phosphors toward broad applications
Three-Dimensional Stiff Graphene Scaffold on Neural Stem Cells Behavior
Physical cues of the scaffolds, elasticity, and stiffness significantly guide adhesion, proliferation, and differentiation of stem cells. In addressable microenvironments constructed by three-dimensional graphene foams (3D-GFs), neural stem cells (NSCs) interact with and respond to the structural geometry and mechanical properties of porous scaffolds. Our studies aim to investigate NSC behavior on the various stiffness of 3D-GFs. Two kinds of 3D-GFs scaffolds present soft and stiff properties with elasticity moduli of 30 and 64 kPa, respectively. Stiff scaffold enhanced NSC attachment and proliferation with vinculin and integrin gene expression were up-regulated by 2.3 and 1.5 folds, respectively, compared with the soft one. Meanwhile, up-regulated Ki67 expression and almost no variation of nestin expression in a group of the stiff scaffold were observed, implying that the stiff substrate fosters NSC growth and keeps the cells in an active stem state. Furthermore, NSCs grown on stiff scaffold exhibited enhanced differentiation to astrocytes. Interestingly, differentiated neurons on stiff scaffold are suppressed since growth associated protein-43 expression was significantly improved by 5.5 folds