Near-infrared quantum cutting in Tm3+/Yb3+-doped phosphate glasses

Abstract A series of phosphate glasses with compositions of 30SrO-60P2O5-10Na2O-0.5Tm2O3-xYb2O3(x = 0, 1, 5, 9, 11 in mol%) were manufactured by melt-casting method, the quantum cutting between the Tm3+ and Yb3+ in the phosphate glasses is investigated, the energy transfer from Tm3+:1G4 to Yb3+:2F5/2 is proved. According to calculate, the highest quantum efficiency is up to 159.9%, the emission wavelength is at 1020 nm, matching the energy band gap of a silicon solar cell well, therefor, these phosphate glasses could potentially be used in silicon solar cells

catena-Poly[[[diaqua­bis(2-methyl-6-oxo-1,6-dihydro-3,4′-bipyridine-5-carbo­nitrile)copper(II)]-μ-sulfato] tetra­hydrate]

In the title polymer, {[Cu(SO4)(C12H9N3O)2(H2O)2]·4H2O}n, both the metal center and the sulfate anion are located on a twofold axis. The CuII ion is coordinated by two pyridyl N atoms from two symmetry-related organic ligands, two O atoms from two symmetry-related water mol­ecules, and two O atoms from two symmetry-related sulfate anions, resulting in a distorted octa­hedral geometry. The sulfate anions act as μ2-bridges and connect metal ions, forming a one-dimensional chain along the b axis. The three-dimensional crystal structure is established through inter­molecular N—H⋯O and O—H⋯O hydrogen bonds involving the organic ligands, sulfate anions, coordinated and uncoordinated water mol­ecules, and through π–π inter­acting 2-pyridone rings, with centroid–centroid separations of ca 3.96 Å and tilt angles of ca 2.62°

Humanin Rescues Cultured Rat Cortical Neurons from NMDA-Induced Toxicity Not by NMDA Receptor

Excitatory neurotoxicity has been implicated in many pathological situations and there is no effective treatment available. Humanin is a 24-aa peptide cloned from the brain of patients with Alzheimer’s disease (AD). In the present study, excitatory toxicity was induced by N-methyl-D-aspartate (NMDA) in primarily cultured rat cortical neurons. MTT assessment, lactate dehydrogenase (LDH) release, and calcein staining were employed to evaluate the protective activity of humanin on NMDA induced toxicity. The results suggested that NMDA (100 μmol/L, 2.5 hr) triggered neuronal morphological changes, lactate dehydrogenase (LDH) release (166% of the control), reduction of cell viability (about 50% of the control), and the decrease of living cell density (about 50% of the control). When pretreated with humanin, the toxicity was suppressed. The living cells’ density of humanin treated group was similar to that of control. The cell viability was attenuated dose-dependently (IC50 = 0.132 nmol/L). The LDH release was also neutralized in a dose-dependent manner. In addition, the intracellular Ca2+ overloading triggered by NMDA reverted quickly and humanin could not inhibit it. These findings indicate that humanin can rescue cortical neurons from NMDA-induced toxicity in rat but not through interfering with NMDA receptor directly

Distance-dependent plasmon-enhanced fluorescence of upconversion nanoparticles using polyelectrolyte multilayers as tunable spacers

Lanthanide-doped upconversion nanoparticles (UCNPs) have attracted widespread interests in bioapplications due to their unique optical properties by converting near infrared excitation to visible emission. However, relatively low quantum yield prompts a need for developing methods for fluorescence enhancement. Plasmon nanostructures are known to efficiently enhance fluorescence of the surrounding fluorophores by acting as nanoantennae to focus electric field into nano-volume. Here, we reported a novel plasmon-enhanced fluorescence system in which the distance between UCNPs and nanoantennae (gold nanorods, AuNRs) was precisely tuned by using layer-by-layer assembled polyelectrolyte multilayers as spacers. By modulating the aspect ratio of AuNRs, localized surface plasmon resonance (LSPR) wavelength at 980 nm was obtained, matching the native excitation of UCNPs resulting in maximum enhancement of 22.6-fold with 8 nm spacer thickness. These findings provide a unique platform for exploring hybrid nanostructures composed of UCNPs and plasmonic nanostructures in bioimaging applications