Cationic Ir(III) Complexes with 4-Fluoro-4'-pyrazolyl-(1,1'-biphenyl)-2-carbonitrile as the Cyclometalating Ligand: Synthesis, Characterizations, and Application to Ultrahigh-Efficiency Light-Emitting Electrochemical Cells.

Light-emitting electrochemical cells (LECs) promise low-cost, large-area luminescence applications with air-stabilized electrodes and a versatile fabrication that enables the use of solution processes. Nevertheless, the commercialization of LECs is still encountering many obstacles, such as low electroluminescence (EL) efficiencies of the ionic materials. In this paper, we propose five blue to yellow ionic Ir complexes possessing 4-fluoro-4'-pyrazolyl-(1,1'-biphenyl)-2-carbonitrile (ppfn) as a novel cyclometalating ligand and use them in LECs. In particular, the device within di[4-fluoro-4'-pyrazolyl-(1,1'-biphenyl)-2-carbonitrile]-4,4'-di-tert-butyl-2,2'-bipyridyl iridium(III) hexafluorophosphate (DTBP) shows a remarkable photoluminescence quantum yield (PLQY) of 70%, and by adjusting the emissive-layer thickness, the maximal external quantum efficiency (EQE) reaches 22.15% at 532 nm under the thickness of 0.51 µm, showing the state-of-the-art value for the reported blue-green LECs.

Perovskite Light-Emitting Electrochemical Cells Employing Electron Injection/Transport Layers of Ionic Transition Metal Complexes.

Invited for the cover of this issue are Chin-Wei Lu, Zu-Po Yang, Hai-Ching Su, and co-workers at National Yang Ming Chiao Tung University and Providence University. The image depicts electron transport for light-emitting electrochemical cells. Read the full text of the article at 10.1002/chem.202103739.

Perovskite Light-Emitting Electrochemical Cells Employing Electron Injection/Transport Layers of Ionic Transition Metal Complexes.

Recently, perovskites have attracted intense attention due to their high potential in optoelectronic applications. Employing perovskites as the emissive materials of light-emitting electrochemical cells (LECs) shows the advantages of simple fabrication process, low-voltage operation, and compatibility with inert electrodes, along with saturated electroluminescence (EL) emission. Unlike in previously reported perovskite LECs, in which salts are incorporated in the emissive layer, the ion-transport layer was separated from the emissive layer in this work. The layer of ionic transition metal complex (iTMC) not only provides mobile ions but also serves as an electron-injection/transport layer. Orthogonal solvents are used in spin coating to prevent the intermixing of stacked perovskite and iTMC layers. The blue iTMC with high ionization potential is effective in blocking holes from the emissive layer and thus ensures EL color saturation. In addition, the carrier balance of the perovskite/iTMC LECs can be optimized by adjusting the iTMC layer thickness. The optimized external quantum efficiency of the CsPbBr3 /iTMC LEC reaches 6.8 %, which is among the highest reported values for perovskite LECs. This work successfully demonstrates that, compared with mixing all components in a single emissive layer, separating the layer of ion transport, electron injection and transport from the perovskite emissive layer is more effective in adjusting device carrier balance. As such, solution-processable perovskite/iTMC LECs open up a new way to realize efficient perovskite LECs.

Rational Design of Redox-Responsive and P-gp-Inhibitory Lipid Nanoparticles with High Entrapment of Paclitaxel for Tumor Therapy.

An insufficient drug concentration at the target site and drug efflux resulting in poor efficacy is recognized as important obstacles in tumor treatment. Herein, novel lipid nanoparticles (LNPs) with redox-responsive properties based on disulfide bond-contained, quercetin (Qu)-grafted glyceryl caprylate-caprate (Gcc) are introduced (Qu-SS-Gcc LNPs). Qu-SS-Gcc LNPs show good entrapment of paclitaxel (PTX) due to π-π stacking between the aromatic rings of Qu and PTX. In vitro experiments indicate that Qu-SS-Gcc LNPs can selectively respond to high levels of reducing substances by breakdown of disulfide bonds, thus achieving rapid and efficient drug release, and only dissociate rapidly in tumor cells rather than in normal cells. Meanwhile, the Qu released concomitantly with the breakdown of disulfide bonds combines with P-gp and inhibits the drug efflux triggered by P-gp. Using an orthotopic 4T1 mouse mammary tumor model in BALB/c mice, PTX/Qu-SS-Gcc LNPs exhibit superior antitumor efficacy compared to Taxol, in addition better biosafety and inhibition of chemotherapy-triggered P-gp overexpression are achieved. Taken together, this work designs and implements redox-responsive drug release and drug efflux inhibition in tumor cells via modified LNPs, which not only leads to efficient drug release but also solves the problem of drug efflux that exists in stimulus-responsive systems.

Improving hyperglycemic effect of FGF-21 is associated with alleviating inflammatory state in diabetes.

Type 2 diabetes mellitus (T2DM) is accompanied by abnormal glucose metabolism and low-grade chronic inflammation. Fibroblast growth factor 21 (FGF-21) is a novel metabolic regulator and can function as an endocrine hormone to regulate glucose and lipid metabolism. Recently, FGF-21 was found to have anti-inflammatory effect, to our knowledge, the effect of FGF-21 on inflammatory state in diabetes has not been elucidated. Here, we use db/db mice as a Type 2 diabetes model to determine whether FGF-21 alleviates inflammatory state while improves hyperglycemia. Our results demonstrated that FGF-21 not only showed potent long lasting hypoglycemic effect, but also demonstrated strong anti-inflammatory effect in the serum and white adipose tissue. Besides, in vitro experiments, insulin resistance (IR) was induced in 3T3-L1 adipocytes by treating with TNF-α. Our results showed that TNF-α impaired glucose metabolism of 3T3-L1 adipocytes but FGF-21 repressed gene expression of inflammatory factors caused by IR and consequently improved the glucose metabolism in 3T3-L1 adipocytes. Furthermore, FGF-21 ameliorated glucose uptake of TNF-α-induced IR in 3T3-L1 adipocytes by inhibiting NF-κB signaling pathway.