The Effect of Hypoxic Preconditioning on Induced Schwann Cells under Hypoxic Conditions

<div><p>Object</p><p>Our objective was to explore the protective effects of hypoxic preconditioning on induced Schwann cells exposed to an environment with low concentrations of oxygen. It has been observed that hypoxic preconditioning of induced Schwann cells can promote axonal regeneration under low oxygen conditions.</p><p>Method</p><p>Rat bone marrow mesenchymal stem cells (MSCs) were differentiated into Schwann cells and divided into a normal oxygen control group, a hypoxia-preconditioning group and a hypoxia group. The ultrastructure of each of these groups of cells was observed by electron microscopy. In addition, flow cytometry was used to measure changes in mitochondrial membrane potential. Annexin V-FITC/PI staining was used to detect apoptosis, and Western blots were used to detect the expression of Bcl-2/Bax. Fluorescence microscopic observations of axonal growth in NG-108 cells under hypoxic conditions were also performed.</p><p>Results</p><p>The hypoxia-preconditioning group maintained mitochondrial cell membrane and crista integrity, and these cells exhibited less edema than the hypoxia group. In addition, the cells in the hypoxia-preconditioning group were found to be in early stages of apoptosis, whereas cells from the hypoxia group were in the later stages of apoptosis. The hypoxia-preconditioning group also had higher levels of Bcl-2/Bax expression and longer NG-108 cell axons than were observed in the hypoxia group.</p><p>Conclusion</p><p>Hypoxic preconditioning can improve the physiological state of Schwann cells in a severe hypoxia environment and improve the ability to promote neurite outgrowth.</p></div

Post-Synthetic Doping and Ligand Engineering of Cs₂AgInCl₆ Double Perovskite Nanocrystals

Lead-free double perovskite (DP) nanocrystals (NCs) have emerged as a promising class of perovskite nanomaterials with potential applications in various optical and optoelectronic domains. Meanwhile, doping impurity ions into perovskite structures represents a unique and effective means to tailor and optimize the properties of perovskite materials. Herein, we introduce a postsynthetic doping approach to the fabrication of Mn2+-doped Cs2AgInCl6 DP NCs with enhanced optical characteristics. We demonstrate that, in the postsynthetic reaction, the initial surface-doped Mn2+ ions undergo a gradual inward migration process within the NCs, resulting in homogeneous Mn2+ doping with a maximum photoluminescence (PL) quantum yield (QY) of 5.2%. This PL QY value can be further improved to 8.2% through codoping with Na+ ions and careful engineering of the NC surface state. In-depth studies involving conventional one-dimensional proton and two-dimensional NMR spectroscopic techniques unveil the pivotal role played by the surface ligands and their states. Based on our findings, we propose a comprehensive postsynthetic doping mechanism. Our study not only presents an accessible doping technique for lead-free perovskite NCs but also offers valuable insights into the dopant dynamics and ligand engineering for perovskite-type nanomaterials in a broader context

Cesium Copper Halide Perovskite Nanocrystal-Based Photon-Managing Devices for Enhanced Ultraviolet Photon Harvesting

Space-based solar power harvesting systems with high levels of specific power (the power produced per mass of the mounted photovoltaic cell) are highly desired. In this study, we synthesized high quality lead-free Cs3Cu2Cl5 perovskite nanodisks with efficient ultraviolet (UV) photon absorption, high photoluminescence quantum yields, and a large Stokes shift, which are suitable to serve as photon energy downshifting emitters in the applications of photon-managing devices especially for space solar power harvesting. To demonstrate this possibility, we have fabricated two types of photon-managing devices, i.e., luminescent solar concentrators (LSCs) and luminescent downshifting (LDS) layers. Both experimental results and simulation analyses show that the fabricated LSC and LDS devices exhibit high visible light transmission, low photon scattering and reabsorption energy loss, high UV photon harvesting, and energy conversion after integrating with silicon-based photovoltaic cells. Our research presents a new avenue for utilizing lead-free perovskite nanomaterials in space applications

The figure represent the apoptosis rate potential of induced Schwann cells in different groups.

<p>There were four quadrants. The high-left quadrant represent the necrosis cells, the low-left quadrant represent the normal cells, the high-right quadrant represent the cells at early stages, and the low-right quadrant represent the cells at late stages. In the conventional oxygen group, most of the induced Schwann cells were not apoptosis or necrosis, the figure showed most of them located in the low-left quadrant.While In the hypoxia-preconditioning group, most cells were in the high-right quadrant,and In the hypoxia group, most cells were in the high-right quadrant. It showed that most cells in hypoxia-preconditioning group were at early stage of apoptosis and most cells in hypoxia group were at late stage of apoptosis.</p

The Effect of Hypoxic Preconditioning on Induced Schwann Cells under Hypoxic Conditions - Table 3

<p>Value are mean±SD</p><p>*P<0.05, compare with the conventional oxygen group</p><p># P<0.05, compare with the hypoixia oxygen group</p><p>The Effect of Hypoxic Preconditioning on Induced Schwann Cells under Hypoxic Conditions - Table 3 </p

The Effect of Hypoxic Preconditioning on Induced Schwann Cells under Hypoxic Conditions - Table 1

<p>Value are mean±SD</p><p>*P<0.05, compare with the conventional oxygen group</p><p># P<0.05, compare with the hypoixia oxygen group</p><p>The Effect of Hypoxic Preconditioning on Induced Schwann Cells under Hypoxic Conditions - Table 1 </p

Images from the hypoxia group reveal partial cell membrane disintegration, the whole cell vacuole.

<p>organelle fragmentation and disintegration, lysosomal vesicles appear, swelling of the rough endoplasmic reticulum and mitochondria, mitochondria vacuole, mitochondrial cristae shortening and rupture, partial swelling and rupturing of the nuclear membrane, and the nucleolus shrinkage. M: mitochondria RER:rough endoplasmic reticulum N:nucleolus, nm: nuclear membrane, cm: cell membrane.</p

Images from the hypoxia-preconditioning group reveal cell swelling, no obvious cell membrane disintegration, no obvious swelling of mitochondria, mitochondrial cristae with clear and complete structures, Rough endoplasmic reticulum is not dilated, partial nucleolus shrinkage, nuclear membrane integrity.

<p>M: mitochondria RER:rough endoplasmic reticulum N:nucleolus, nm: nuclear membrane, cm: cell membrane.</p

a. Positive expression of S-100 in induced Schwann cells. b. Positive expression of GFAP in induced Schwann cells.

<p>a. Positive expression of S-100 in induced Schwann cells. b. Positive expression of GFAP in induced Schwann cells.</p

The figure represent the mitochondrial membrane potential of induced Schwann cells in different groups.

<p>The points located in the upper-right quadrant represent the number of induced Schwann cells whose mitochondrial membrane potential is not declined. In conventional oxygen group, 94.1±0.2% of the tested induced Schwann cells were in the upper-right quadrant, the hypoxia-preconditioning group, 90.1±0.1% of the tested induced Schwann cells were in the upper-right quadrant, the hypoxia group, 80.6±0.6% of the tested induced Schwann cells were in the upper-right quadrant. The conventional oxygen group had highest ratio of induced Schwann cells whose mitochondrial membrane potential is not declined, and the hypoxia group had lowest ratio of induced Schwann cells whose mitochondrial membrane potential is not declined.</p