Foldable Hole-Transporting Materials for Merging Electronic States between Defective and Perfect Perovskite Sites.

Defective and perfect sites naturally exist within electronic semiconductors, and considerable efforts to reduce defects to improve the performance of electronic devices, especially in hybrid organic-inorganic perovskites (ABX3 ), are undertaken. Herein, foldable hole-transporting materials (HTMs) are developed, and they extend the wavefunctions of A-site cations of perovskite, which, as hybridized electronic states, link the trap states (defective site) and valence band edge (perfect site) between the naturally defective and perfect sites of the perovskite surface, finally converting the discrete trap states of the perovskite as the continuous valence band to reduce trap recombination. Tailoring the foldability of the HTMs tunes the wavefunctions between defective and perfect surface sites, allowing the power conversion efficiency of a small cell to reach 23.22% and that of a mini-module (6.5 × 7 cm, active area = 30.24 cm2 ) to reach as high as 21.71% with a fill factor of 81%, the highest value reported for non-spiro-OMeTAD-based perovskite solar modules.

Asymmetrically Substituted 10H,10'H-9,9'-Spirobi[acridine] Derivatives as Hole-Transporting Materials for Perovskite Solar Cells.

Hole-transporting materials (HTMs) based on the 10H, 10'H-9,9'-spirobi [acridine] core (BSA50 and BSA51) were synthesized, and their electronic properties were explored. Experimental and theoretical studies show that the presence of rigid 3,6-dimethoxy-9H-carbazole moieties in BSA 50 brings about improved hole mobility and higher work function compared to bis(4-methoxyphenyl)amine units in BSA51, which increase interfacial hole transportation from perovskite to HTM. As a result, perovskite solar cells (PSCs) based on BSA50 boost power conversion efficiency (PCE) to 22.65 %, and a PSC module using BSA50 HTM exhibits a PCE of 21.35 % (6.5×7 cm) with a Voc of 8.761 V and FF of 79.1 %. The unencapsulated PSCs exhibit superior stability to devices employing spiro-OMeTAD, retaining nearly 90 % of their initial efficiency after 1000 h operation output. This work demonstrates the high potential of molecularly engineered spirobi[acridine] derivatives as HTMs as replacements for spiro-OMeTAD.

Pretreatment of nucleus pulposus mesenchymal stem cells with appropriate concentration of H2O2 enhances their ability to treat intervertebral disc degeneration.

BACKGROUND: Nucleus pulposus mesenchymal stem cells (NPMSCs) transplantation is a promising treatment for intervertebral disc degeneration (IVDD). However, the transplanted NPMSCs exhibited weak cell proliferation, high cell apoptosis, and a low ability to resist the harsh microenvironment of the degenerated intervertebral disc. There is an urgent need to explore feasible methods to enhance the therapeutic efficacy of NPMSCs transplantation. OBJECTIVE: To identify the optimal concentration for NPMSCs pretreatment with hydrogen peroxide (H2O2) and explore the therapeutic efficacy of NPMSCs transplantation using H2O2 pretreatment in IVDD. METHODS: Rat NPMSCs were pretreated with different concentrations (range from 25 to 300 µM) of H2O2. The proliferation, reactive oxygen species (ROS) level, and apoptosis of NPMSCs were detected by cell counting kit-8 (CCK-8) assay, 5-ethynyl-2'-deoxyuridine (EdU) staining, and flow cytometry in vitro. The underlying signalling pathways were explored utilizing Western blotting. A rat needle puncture-stimulated IVDD model was established. X-ray, histological staining, and a multimode small animal live imaging system were used to evaluate the therapeutic effect of H2O2-pretreated NPMSCs in vivo. RESULTS: NPMSCs pretreated with 75 µM H2O2 demonstrated the strongest elevated cell proliferation by inhibiting the Hippo pathway (P < 0.01). Meanwhile, 75 µM H2O2-pretreated NPMSCs exhibited significantly enhanced antioxidative stress ability (P < 0.01), which is related to downregulated Brd4 and Keap1 and upregulated Nrf2. NPMSCs pretreated with 75 µM H2O2 also exhibited distinctly decreased apoptosis (P < 0.01). In vivo experiments verified that 75 µM H2O2-pretreated NPMSCs-transplanted rats exhibited an enhanced disc height index (DHI% = 90.00 ± 4.55, P < 0.01) and better histological morphology (histological score = 13.5 ± 0.5, P < 0.01), which means 75 µM H2O2-pretreated NPMSCs can better adapt to the environment of degenerative intervertebral discs and promote the repair of IVDD. CONCLUSIONS: Pretreatment with 75 µM H2O2 was the optimal concentration to improve the proliferation, antioxidative stress, and antiapoptotic ability of transplanted NPMSCs, which is expected to provide a new feasible method to improve the stem cell therapy efficacy of IVDD.

Area-Scalable Zn2SnO4 Electron Transport Layer for Highly Efficient and Stable Perovskite Solar Modules.

The development of a scalable chemical bath deposition (CBD) process facilitates the realization of electron-transporting layers (ETLs) for large-area perovskite solar modules (PSMs). Herein, a method to prepare a uniform and scalable thick Zn2SnO4 ETL by CBD, which yielded high-performance PSMs, is reported. This Zn2SnO4 ETL exhibits excellent electrical properties and enhanced optical transmittance in the visible region. Moreover, the Zn2SnO4 ETL influences the perovskite layer formation, yielding enhanced crystallinity, increased grain size, and a smoother surface, thus facilitating electron extraction and collection from the perovskite to the ETL. Zn2SnO4 thereby yields PSMs with a remarkable photovoltaic performance, low hysteresis index, and high device reproducibility. The champion PSM exhibited a power conversion efficiency (PCE) of 22.59%, being among the highest values published so far. In addition, the CBD Zn2SnO4-based PSMs exhibit high stability, retaining more than 88% of initial efficiency over 1000 h under continuous illumination. This demonstrates that CBD Zn2SnO4 is an appropriate ETL for high-efficiency PSMs and a viable new process for their industrialization.

The biological effect of cobalt chloride mimetic-hypoxia on nucleus pulposus cells and the comparability with physical hypoxia in vitro.

Objective: Nucleus pulposus cells (NPCs) are cells extracted from the intervertebral disc and are important for research into intervertebral disc degeneration (IVDD). NPCs live in an avascular and relatively hypoxic environment. Cobalt chloride (CoCl2) has been used in many cell studies to mimic hypoxia. The objective of this study was to explore the possibility of using CoCl2 to induce mimetic-hypoxia for NPCs and the comparison with hypoxia (1% O2) in vitro. Materials and methods: Rat nucleus pulposus cells of Passage 3-5 were used in this research. Cell viability, rate of cell apoptosis, ROS (reactive oxygen species) generation, cell migration, extracellular pH and extracellular matrix metabolism were determined to compare the influence of hypoxia (1% O2) and CoCl2 on NPCs. Results: We found that the effects of CoCl2 on NPCs was dose-dependent. At the proper concentration, CoCl2 could be used to elicit chemical hypoxia for nucleus pulposus cells in vitro and many biological effects, analogous to physical hypoxia (1% O2), could be achieved such as enhanced cell viability, decreased apoptosis and activated extracellular matrix metabolism. On the other hand, CoCl2 mimetic-hypoxia did not affect NPCs glycolysis and migration compared to physical hypoxia. In addition, high concentration of CoCl2 (>200 µM) is harmful to NPCs with high rates of apoptosis and ECM (extracellular matrix) degradation. Conclusions: It is feasible and convenient to use CoCl2 to induce chemical mimetic hypoxia for culturing NPCs on the premise of appropriate concentration. But in aspects of cell migration and glycolysis, CoCl2 could not achieve similar results with physical hypoxia. This study may provide a convenient method and enlightenment to induce mimetic-hypoxia for researchers studying NPCs and IVVD.

Exosomes derived from stem cells as an emerging therapeutic strategy for intervertebral disc degeneration.

Intervertebral disc (IVD) degenerative diseases are a common problem in the world, and they cause substantial social and economic burdens for people. The current methods for treating IVD degenerative diseases mainly include surgery and conservative treatment, which cannot fundamentally restore the normal structure of the disc. With continuous research on the mechanism of degeneration and the development of regenerative medicine, rapid progress has been made in the field of regenerative medicine regarding the use of stem cell-derived exosomes, which are active biological substances used in intercellular communication, because they show a strong effect in promoting tissue regeneration. The study of exosomes in the field of IVD degeneration has just begun, and many surprising achievements have been made. This paper mainly reviews the biological characteristics of exosomes and highlights the current status of exosomes in the field of IVD degeneration, as well as future developments regarding exosomes.

An Efficient Approach to Fabricate Air-Stable Perovskite Solar Cells via Addition of a Self-Polymerizing Ionic Liquid.

Despite the excellent photovoltaic properties achieved by perovskite solar cells at the laboratory scale, hybrid perovskites decompose in the presence of air, especially at high temperatures and in humid environments. Consequently, high-efficiency perovskites are usually prepared in dry/inert environments, which are expensive and less convenient for scale-up purposes. Here, a new approach based on the inclusion of an in situ polymerizable ionic liquid, 1,3-bis(4-vinylbenzyl)imidazolium chloride ([bvbim]Cl), is presented, which allows perovskite films to be manufactured under humid environments, additionally leading to a material with improved quality and long-term stability. The approach, which is transferrable to several perovskite formulations, allows efficiencies as high as 17% for MAPbI3 processed in air % relative humidity (RH) ≥30 (from an initial 15%), and 19.92% for FAMAPbI3 fabricated in %RH ≥50 (from an initial 17%), providing one of the best performances to date under similar conditions.

Stable and High-Efficiency Methylammonium-Free Perovskite Solar Cells.

Organic-inorganic metal halide perovskite solar cells (PSCs) have achieved certified power conversion efficiency (PCE) of 25.2% with complex compositional and bandgap engineering. However, the thermal instability of methylammonium (MA) cation can cause the degradation of the perovskite film, remaining a risk for the long-term stability of the devices. Herein, a unique method is demonstrated to fabricate highly phase-stable perovskite film without MA by introducing cesium chloride (CsCl) in the double cation (Cs, formamidinium) perovskite precursor. Moreover, due to the suboptimal bandgap of bromide (Br- ), the amount of Br- is regulated, leading to high power conversion efficiency. As a result, MA-free perovskite solar cells achieve remarkable long-term stability and a PCE of 20.50%, which is one of the best results for MA-free PSCs. Moreover, the unencapsulated device retains about 80% of the original efficiencies after a 1000 h aging study. These results provide a feasible approach to enhance solar cell stability and performance simultaneously, paving the way for commercializing PSCs.

Tuning the Fermi-level of TiO2 mesoporous layer by lanthanum doping towards efficient perovskite solar cells.

Tuning the band alignment is proved to be an effective way to facilitate carrier transportation and thus enhance the power conversion efficiency (PCE) of solar cells. Doping the compact layer with metal ions or modifying the interfaces among functional layers in perovskite solar cells (PSCs) can appreciably improve the PCE of PSCs. Inspired by the rare earth elemental doping of TiO2, which has witnessed the success in photocatalysis and dye-sensitized solar cells, we firstly demonstrated here that La3+ doping in the mesoporous TiO2 layer of a mesostructured PSC can tune its Fermi level and thus significantly enhance the device PCE. Systematic analysis reveals that doping La3+ into TiO2 raises the Fermi level of TiO2 through scavenging oxygen and inducing vacancies, which subsequently increases the open circuit voltage and the fill factor while reducing the series resistance of the PSC using La3+-doped TiO2 as a mesoporous layer. As a result, a PCE of 15.42% is achieved, which is appreciably higher than the PCE of a device with undoped TiO2 (12.11%).

Subchronic toxicological study of two artemisinin derivatives in dogs.

The objective of our study was to profile and compare the systematic changes between orally administered artesunate and intramuscularly injected artemether at a low dose over a 3-month period (92 consecutive days) in dogs. Intramuscular administration of 6 mg kg-1 artemether induced a decreased red blood cell (RBC) count (anemia), concurrent extramedullary hematopoiesis in the spleen and inhibition of erythropoiesis in the bone marrow. We also observed a prolonged QT interval and neuropathic changes in the central nervous system, which demonstrated the cortex and motor neuron vulnerability, but no behavioral changes. Following treatment with artesunate, we observed a decreased heart rate, which was most likely due to cardiac conduction system damage, as well as a deceased RBC count, extramedullary hematopoiesis in the spleen and inhibition of erythropoiesis in the bone marrow. However, in contrast to treatment with artemether, neurotoxicity was not observed following treatment with artesunate. In addition, ultra-structural examination by transmission electron microscopy showed mitochondrial damage following treatment with artesunate. These findings demonstrated the spectrum of toxic changes that result upon treatment with artesunate and artemether and show that the prolonged administration of low doses of these derivatives result in diverse toxicity profiles.