Highly activated oxygen redox enabling large-capacity Li-rich layered manganese-based oxide cathodes.

Li-rich Mn-based layered materials are considered the most promising next-generation high-energy-density cathode materials due to their high capacity, but their large irreversible capacity loss and severe voltage attenuation hinder their practical application. The limited operating voltage also makes it difficult to satisfy the increasing demand of high energy density in future applications. Inspired by the high voltage platform of Ni-rich LiNi0.8Co0.1Mn0.1O2, we design and prepare a Li1.2Ni0.32Co0.04Mn0.44O2 (LLMO811) cathode material with increased Ni content via the acrylic acid polymerization method and regulate the amounts of excess lithium of LLMO. It is found that LLMO-L3 with 3% excess lithium has the highest initial discharge capacity of 250 mA h g-1 with a coulombic efficiency of 83.8%. Taking advantage of a high operating voltage of about 3.75 V, the material achieves an impressive high energy density of 947 W h kg-1. Moreover, the capacity at 1C reaches 193.2 mA h g-1, which is higher than that of ordinary LLMO811. This large capacity is attributed to the highly reversible O redox reaction, and the strategy used to achieve this would throw some light on the exploration of high-energy-density cathodes.

Magnetron sputtering of platinum on nitrogen-doped polypyrrole carbon nanotubes as an efficient and stable cathode for lithium-carbon dioxide batteries.

As an emerging green energy storage and conversion system, rechargeable Li-CO2 batteries have undergone extensive research due to their ultra-high energy density and their significant role in greenhouse gas CO2 conversion. However, current Li-CO2 batteries have some shortcomings that severely limit their large-scale application. The most critical problems involve the insulation of the discharge product Li2CO3 and the slow decomposition kinetics, meaning that the battery generates a large overpotential and has a low cycle life, so the rational design of an efficient cathode catalyst is imperative. Here, we prepared a composite material via the magnetron sputtering of Pt onto nitrogen-doped polypyrrole carbon nanotubes (NPPy-CNTs) as a high-efficiency cathode catalyst for Li-CO2 batteries. The three-dimensional hollow tubular NPPy-CNTs can provide efficient channels for CO2 diffusion and enough space for the uniform deposition and decomposition of Li2CO3. Benefiting from the doping of nitrogen, more defects and active sites are introduced into the polypyrrole carbon nanotubes. Furthermore, the introduction of a small amount of the precious metal Pt effectively improves the catalytic activity of the CO2 reduction reaction (CO2RR) and the CO2 release reaction (CO2ER), greatly improving the cycle life of the battery. The Pt-NPPy-CNT-based battery shows a much improved electrochemical performance. The overpotential of the battery is reduced to 0.75 V, and the battery shows a specific discharge capacity of up to 29 614 mA h g-1.

Suppression and Mechanism of Voltage Decay in Sb-Doped Lithium-Rich Layered Oxide Cathode Materials.

Voltage decay during cycling is the major problem for lithium-rich layered oxide cathodes. Here, we designed Sb-doped lithium-rich layered oxides prepared by a coprecipitation-solvent thermal method, aiming to alleviate the voltage decay of lithium-rich layered oxides. The midpoint discharge voltage and specific capacity of Li1.20Ni0.133Co0.133Mn0.633Sb0.01O2 (LLMO-Sb1) demonstrate almost no decaying after 100 cycles at 1 C. Moreover, it exhibits a large rate capacity (215 mAh g-1 at 5 C). The suppressed voltage decay and enhanced cycle performance of Sb-doped material are attributed to the high Sb-O bond energy, which can enhance the stability of the layered structure and suppress the layered-to-spinel phase transition. Moreover, Sb doping improves the rate capacity by reducing the energy barrier of lithium ion diffusion. This work opens a gate to prevent the oxidation of superoxo and peroxo, stabilizing the layered structure by selecting an element with a suitable radius and electronegativity.

Promoting the Performance of Li-CO2 Batteries via Constructing Three-Dimensional Interconnected K+ Doped MnO2 Nanowires Networks.

Nowadays, Li-CO2 batteries have attracted enormous interests due to their high energy density for integrated energy storage and conversion devices, superiorities of capturing and converting CO2. Nevertheless, the actual application of Li-CO2 batteries is hindered attributed to excessive overpotential and poor lifespan. In the past decades, catalysts have been employed in the Li-CO2 batteries and been demonstrated to reduce the decomposition potential of the as-formed Li2CO3 during charge process with high efficiency. However, as a representative of promising catalysts, the high costs of noble metals limit the further development, which gives rise to the exploration of catalysts with high efficiency and low cost. In this work, we prepared a K+ doped MnO2 nanowires networks with three-dimensional interconnections (3D KMO NWs) catalyst through a simple hydrothermal method. The interconnected 3D nanowires network catalysts could accelerate the Li ions diffusion, CO2 transfer and the decomposition of discharge products Li2CO3. It is found that high content of K+ doping can promote the diffusion of ions, electrons and CO2 in the MnO2 air cathode, and promote the octahedral effect of MnO6, stabilize the structure of MnO2 hosts, and improve the catalytic activity of CO2. Therefore, it shows a high total discharge capacity of 9,043 mAh g-1, a low overpotential of 1.25 V, and a longer cycle performance.

Sn-Doping and Li2SnO3 Nano-Coating Layer Co-Modified LiNi0.5Co0.2Mn0.3O2 with Improved Cycle Stability at 4.6 V Cut-off Voltage.

Nickel-rich layered LiNi1-x-yCoxMnyO2 (LiMO2) is widely investigated as a promising cathode material for advanced lithium-ion batteries used in electric vehicles, and a much higher energy density in higher cut-off voltage is emergent for long driving range. However, during extensive cycling when charged to higher voltage, the battery exhibits severe capacity fading and obvious structural collapse, which leads to poor cycle stability. Herein, Sn-doping and in situ formed Li2SnO3 nano-coating layer co-modified spherical-like LiNi0.5Co0.2Mn0.3O2 samples were successfully prepared using a facile molten salt method and demonstrated excellent cyclic properties and high-rate capabilities. The transition metal site was expected to be substituted by Sn in this study. The original crystal structures of the layered materials were influenced by Sn-doping. Sn not only entered into the crystal lattice of LiNi0.5Co0.2Mn0.3O2, but also formed Li+-conductive Li2SnO3 on the surface. Sn-doping and Li2SnO3 coating layer co-modification are helpful to optimize the ratio of Ni2+ and Ni3+, and to improve the conductivity of the cathode. The reversible capacity and rate capability of the cathode are improved by Sn-modification. The 3 mol% Sn-modified LiNi0.5Co0.2Mn0.3O2 sample maintained the reversible capacity of 146.8 mAh g-1 at 5C, corresponding to 75.8% of its low-rate capacity (0.1C, 193.7mAh g-1) and kept the reversible capacity of 157.3 mAh g-1 with 88.4% capacity retention after 100 charge and discharge cycles at 1C rate between 2.7 and 4.6 V, showing the improved electrochemical property.

Bimetal-organic Framework-derived Co9 S8 /ZnS@NC Heterostructures for Superior Lithium-ion Storage.

Heterostructure engineering of electrode materials, which is expected to accelerate the ion/electron transport rates driven by a built-in internal electric field at the heterointerface, offers unprecedented promise in improving their cycling stability and rate performance. Herein, carbon nanotubes with Co9 S8 /ZnS heterostructures embedded in a N-doped carbon framework (Co9 S8 /ZnS@NC) have been rationally designed via an in-situ vapor chemical transformation strategy with the aid of thiophene, which not only acted as carbon source for the growth of carbon nanotubes but also as sulfur source for the sulfurization of metal Zn and Co. Density functional theory (DFT) calculation shows an about 3.24 eV electrostatic potential difference between ZnS and Co9 S8 , which results in a strong electrostatic field across the interface that makes electrons transfer from Co9 S8 to the ZnS side. As expected, a stable cycling performance with reversible capacity of 411.2 mAh g-1 at 1000 mA g-1 after 300 cycles, excellent rate capability (324 mAh g-1 at 2000 A g-1 ) and a high percentage of pseudocapacitance contribution (87.5% at 2.2 mv/s) for lithium-ion batteries (LIBs) are achieved. This work provides a possible strategy for designing multicomponent heterostructural materials for application in energy storage and conversion fields.

Submicron-Sized Nb-Doped Lithium Garnet for High Ionic Conductivity Solid Electrolyte and Performance of Quasi-Solid-State Lithium Battery.

The garnet Li7La3Zr2O12 (LLZO) has been widely investigated because of its high conductivity, wide electrochemical window, and chemical stability with regards to lithium metal. However, the usual preparation process of LLZO requires high-temperature sintering for a long time and a lot of mother powder to compensate for lithium evaporation. In this study submicron Li6.6La3Zr1.6Nb0.4O12 (LLZNO) powder-which has a stable cubic phase and high sintering activity-was prepared using the conventional solid-state reaction and the attrition milling process, and Li stoichiometric LLZNO ceramics were obtained by sintering this powder-which is difficult to control under high sintering temperatures and when sintered for a long time-at a relatively low temperature or for a short amount of time. The particle-size distribution, phase structure, microstructure, distribution of elements, total ionic conductivity, relative density, and activation energy of the submicron LLZNO powder and the LLZNO ceramics were tested and analyzed using laser diffraction particle-size analyzer (LD), X-Ray Diffraction (XRD), Scanning Electron Microscope (SEM), Electrochemical Impedance Spectroscopy (EIS), and the Archimedean method. The total ionic conductivity of samples sintered at 1200 °C for 30 min was 5.09 × 10-4 S·cm-1, the activation energy was 0.311 eV, and the relative density was 87.3%. When the samples were sintered at 1150 °C for 60 min the total ionic conductivity was 3.49 × 10-4 S·cm-1, the activation energy was 0.316 eV, and the relative density was 90.4%. At the same time, quasi-solid-state batteries were assembled with LiMn2O4 as the positive electrode and submicron LLZNO powder as the solid-state electrolyte. After 50 cycles, the discharge specific capacity was 105.5 mAh/g and the columbic efficiency was above 95%.

High-Performance Lithium-Rich Layered Oxide Material: Effects of Preparation Methods on Microstructure and Electrochemical Properties.

Lithium-rich layered oxide is one of the most promising candidates for the next-generation cathode materials of high-energy-density lithium ion batteries because of its high discharge capacity. However, it has the disadvantages of uneven composition, voltage decay, and poor rate capacity, which are closely related to the preparation method. Here, 0.5Li2MnO3·0.5LiMn0.8Ni0.1Co0.1O2 was successfully prepared by sol-gel and oxalate co-precipitation methods. A systematic analysis of the materials shows that the 0.5Li2MnO3·0.5LiMn0.8Ni0.1Co0.1O2 prepared by the oxalic acid co-precipitation method had the most stable layered structure and the best electrochemical performance. The initial discharge specific capacity was 261.6 mAh·g-1 at 0.05 C, and the discharge specific capacity was 138 mAh·g-1 at 5 C. The voltage decay was only 210 mV, and the capacity retention was 94.2% after 100 cycles at 1 C. The suppression of voltage decay can be attributed to the high nickel content and uniform element distribution. In addition, tightly packed porous spheres help to reduce lithium ion diffusion energy and improve the stability of the layered structure, thereby improving cycle stability and rate capacity. This conclusion provides a reference for designing high-energy-density lithium-ion batteries.

Simple and green fabrication process of nano silver conductive ink and the application in frequency selective surface.

A simple and green method for fabrication of nano silver conductive ink was developed for use in frequency selective surface (FSS). The hydrogen peroxide and ethyl cellulose were used as reducing agents and dispersants to synthesize silver nanoparticles (Ag NPs), and the ethyl cellulose was be used as binders of nano silver conductive ink eventually. The reaction byproducts of hydrogen peroxide are water and oxygen, the synthesized Ag NPs were be cleaned using purified water and alcohol without centrifugation and drying process. The conductive ink with 30 wt% silver content was formulated with the Ag NPs capped with ethyl cellulose, solvent and additive, the residual water and alcohol were be evaporated using vacuum distillation process. The prepared Ag NPs were characterized by SEM, XRD, TGA and FT-IR. The viscosity and surface tension of Ag NPs ink were tested, and the conductive ink was inkjet printed on Polyimide (PI) film to fabricate the FSS. The results showed the printed FSS had reflection resonances at 16.5 GHz and nulls deeper than the required -20 dB level, with depths of -32 dB.

Effect of Different Composition on Voltage Attenuation of Li-Rich Cathode Material for Lithium-Ion Batteries.

Li-rich layered oxide cathode materials have become one of the most promising cathode materials for high specific energy lithium-ion batteries owning to its high theoretical specific capacity, low cost, high operating voltage and environmental friendliness. Yet they suffer from severe capacity and voltage attenuation during prolong cycling, which blocks their commercial application. To clarify these causes, we synthesize Li1.5Mn0.55Ni0.4Co0.05O2.5 (Li1.2Mn0.44Ni0.32Co0.04O2) with high-nickel-content cathode material by a solid-sate complexation method, and it manifests a lot slower capacity and voltage attenuation during prolong cycling compared to Li1.5Mn0.66Ni0.17Co0.17O2.5 (Li1.2Mn0.54Ni0.13Co0.13O2) and Li1.5Mn0.65Ni0.25Co0.1O2.5 (Li1.2Mn0.52Ni0.2Co0.08O2) cathode materials. The capacity retention at 1 C after 100 cycles reaches to 87.5% and the voltage attenuation after 100 cycles is only 0.460 V. Combining X-ray diffraction (XRD), scanning electron microscope (SEM), and transmission electron microscopy (TEM), it indicates that increasing the nickel content not only stabilizes the structure but also alleviates the attenuation of capacity and voltage. Therefore, it provides a new idea for designing of Li-rich layered oxide cathode materials that suppress voltage and capacity attenuation.

The Effects of Reversibility of H2-H3 Phase Transition on Ni-Rich Layered Oxide Cathode for High-Energy Lithium-Ion Batteries.

Although LiNi0.8Co0.1Mn0.1O2 is attracting increasing attention on account of its high specific capacity, the moderate cycle lifetime still hinders its large-scale commercialization applications. Herein, the Ti-doped LiNi0.8Co0.1Mn0.1O2 compounds are successfully synthesized. The Li(Ni0.8Co0.1Mn0.1)0.99Ti0.01O2 sample exhibits the best electrochemical performance. Under the voltage range of 2.7-4.3 V, it maintains a reversible capacity of 151.01 mAh·g-1 with the capacity retention of 83.98% after 200 cycles at 1 C. Electrochemical impedance spectroscopy (EIS) and differential capacity profiles during prolonged cycling demonstrate that the Ti doping could enhance both the abilities of electronic transition and Li ion diffusion. More importantly, Ti doping can also improve the reversibility of the H2-H3 phase transitions during charge-discharge cycles, thus improving the electrochemical performance of Ni-rich cathodes.

Understanding the Impact of K-Doping on the Structure and Performance of LiFePO4/C Cathode Materials.

The K-doped Li1-xKxFePO4 (x = 0, 0.005, 0.01, and 0.02) samples were synthesized successfully via a solid-state method, and the electronic structures of the samples were calculated by the first-principles based on density functional theory. Theoretical calculations show that the bandwidth of Li1-xKxFePO4 decreases with the increase in K+ doping, which is consistent with the experimental results. It was demonstrated that Li0.995K0.005FePO4 delivers higher capacity retention with 92.7% after 100 cycles compared with LiFePO4 (86.3%) at 1 C and shows better high-rate performance with capacities of 151.9, 151.8, 149.2, 128.3, and 84.6 mAh·g-1 at current densities of 0.1 C, 0.2 C, 0.5 C, 1 C, and 3 C; the corresponding values for LiFePO4 were 153.2, 136.5, 125.9, 111.5, and 66.0 mAh·g-1. Owing to the expanded Li ion diffusion pathway, EIS analysis showed that the lithium ion diffusion coefficient of LiFePO4 doped with K ion was significantly improved compared to LiFePO4; the values were 1.934×10-13 and 1.658×10-12 cm²·s-1, respectively. Additionally, Li0.995K0.005FePO4 showed a lower charge transfer resistance (300.2 Ω compared to 407.1 Ω of LiFePO4).

Porous Hollow Superlattice NiMn2O4/NiCo2O4 Mesocrystals as a Highly Reversible Anode Material for Lithium-Ion Batteries.

As a promising high-capacity anode material for Li-ion batteries, NiMn2O4 always suffers from the poor intrinsic conductivity and the architectural collapse originating from the volume expansion during cycle. Herein, a combined structure and architecture modulation is proposed to tackle concurrently the two handicaps, via a facile and well-controlled solvothermal approach to synthesize NiMn2O4/NiCo2O4 mesocrystals with superlattice structure and hollow multi-porous architecture. It is demonstrated that the obtained NiCo1.5Mn0.5O4 sample is made up of a new mixed-phase NiMn2O4/NiCo2O4 compound system, with a high charge capacity of 532.2 mAh g-1 with 90.4% capacity retention after 100 cycles at a current density of 1 A g-1. The enhanced electrochemical performance can be attributed to the synergistic effects of the superlattice structure and the hollow multi-porous architecture of the NiMn2O4/NiCo2O4 compound. The superlattice structure can improve ionic conductivity to enhance charge transport kinetics of the bulk material, while the hollow multi-porous architecture can provide enough void spaces to alleviate the architectural change during cycling, and shorten the lithium ions diffusion and electron-transportation distances.

Improved Electrochemical Performance of Surface Coated LiNi0.80Co0.15Al0.05O2 With Polypyrrole.

Nickel-rich ternary layered oxide (LiNi0.80Co0.15Al0.05O2, LNCA) cathodes are favored in many fields such as electric vehicles due to its high specific capacity, low cost, and stable structure. However, LNCA cathode material still has the disadvantages of low initial coulombic efficiency, rate capability and poor cycle performance, which greatly restricts its commercial application. To overcome this barrier, a polypyrrole (PPy) layer with high electrical conductivity is designed to coat on the surface of LNCA cathode material. PPy coating layer on the surface of LNCA successfully is realized by means of liquid-phase chemical oxidation polymerization method, and which has been verified by the scanning electron microscopy (SEM), transmission electron microscope (TEM) and fourier transform infrared spectroscopy (FTIR). PPy-coated LNCA (PL-2) exhibits satisfactory electrochemical performances including high reversible capacity and excellent rate capability. Furthermore, the capability is superior to pristine LNCA. So, it provides a new structure of conductive polymer modified cathode materials with good property through a mild modification method.

High Performance and Structural Stability of K and Cl Co-Doped LiNi0.5Co0.2Mn0.3O2 Cathode Materials in 4.6 Voltage.

The high energy density lithium ion batteries are being pursued because of their extensive application in electric vehicles with a large mileage and storage energy station with a long life. So, increasing the charge voltage becomes a strategy to improve the energy density. But it brings some harmful to the structural stability. In order to find the equilibrium between capacity and structure stability, the K and Cl co-doped LiNi0.5Co0.2Mn0.3O2 (NCM) cathode materials are designed based on defect theory, and prepared by solid state reaction. The structure is investigated by means of X-ray diffraction (XRD), rietveld refinements, scanning electron microscope (SEM), XPS, EDS mapping and transmission electron microscope (TEM). Electrochemical properties are measured through electrochemical impedance spectroscopy (EIS), cyclic voltammogram curves (CV), charge/discharge tests. The results of XRD, EDS mapping, and XPS show that K and Cl are successfully incorporated into the lattice of NCM cathode materials. Rietveld refinements along with TEM analysis manifest K and Cl co-doping can effectively reduce cation mixing and make the layered structure more complete. After 100 cycles at 1 C, the K and Cl co-doped NCM retains a more integrated layered structure compared to the pristine NCM. It indicates the co-doping can effectively strengthen the layer structure and suppress the phase transition to some degree during repeated charge and discharge process. Through CV curves, it can be found that K and Cl co-doping can weaken the electrode polarization and improve the electrochemical performance. Electrochemical tests show that the discharge capacity of Li0.99K0.01(Ni0.5Co0.3Mn0.2)O1.99Cl0.01 (KCl-NCM) are far higher than NCM at 5 C, and capacity retention reaches 78.1% after 100 cycles at 1 C. EIS measurement indicates that doping K and Cl contributes to the better lithium ion diffusion and the lower charge transfer resistance.

Building Honeycomb-Like Hollow Microsphere Architecture in a Bubble Template Reaction for High-Performance Lithium-Rich Layered Oxide Cathode Materials.

In the family of high-performance cathode materials for lithium-ion batteries, lithium-rich layered oxides come out in front because of a high reversible capacity exceeding 250 mAh g-1. However, the long-term energy retention and high energy densities for lithium-rich layered oxide cathode materials require a stable structure with large surface areas. Here we propose a "bubble template" reaction to build "honeycomb-like" hollow microsphere architecture for a Li1.2Mn0.52Ni0.2Co0.08O2 cathode material. Our material is designed with ca. 8-µm-sized secondary particles with hollow and highly exposed porous structures that promise a large flexible volume to achieve superior structure stability and high rate capability. Our preliminary electrochemical experiments show a high capacity of 287 mAh g-1 at 0.1 C and a capacity retention of 96% after 100 cycles at 1.0 C. Furthermore, the rate capability is superior without any other modifications, reaching 197 mAh g-1 at 3.0 C with a capacity retention of 94% after 100 cycles. This approach may shed light on a new material engineering for high-performance cathode materials.

Alleviating Surface Degradation of Nickel-Rich Layered Oxide Cathode Material by Encapsulating with Nanoscale Li-Ions/Electrons Superionic Conductors Hybrid Membrane for Advanced Li-Ion Batteries.

Nickel-rich layered oxide cathode materials for advanced lithium-ion batteries have received much attention recently because of their high specific capacities and significant reduction of cost. However, these cathodes are facing a fundamental challenge of loss in performance as a result of surface lithium residue, side reactions with the electrolyte and structure rearrangement upon long-term cycling. Herein, by capturing the lithium residue on the surface of LiNi0.8Co0.1Mn0.1O2 (NCM) cathode material as Li source, we propose a hybrid coating strategy incorporating lithium ions conductor LixAlO2 with superconductor LixTi2O4 to overcome those obstinate issues. By taking full advantage of this unique hybrid nanomembrane coating architecture, both the lithium ion diffusion ability and electronic conductivity of LiNi0.8Co0.1Mn0.1O2 cathode material are improved, resulting in remarkably enhanced electrochemical performances during high voltage operation, including good cycle performance, high reversible capacity, and excellent rate capability. A high initial discharge capacity of 227 mAh g-1 at 4.4 V cutoff voltage with Coulombic efficiency of 87.3%, and reversible capacity of 200 mAh g-1 with 98% capacity retention after 100 cycles at a current density of 0.5 C can be attained. The improved electrochemical performance can be attributed to the synergetic contribution from the removal of lithium residues and the unique hybrid nanomembrane coating architecture. Most importantly, this surface modification technique could save some cost, simplify the technical procedure, and show great potential to optimize battery performance, apply in a large scale and extend to all nickel-rich cathode material.

Carbon liberated from CO-releasing molecules attenuates leukocyte infiltration in the small intestine of thermally injured mice.

AIM: To determine whether Carbon (CO) liberated from CO-releasing molecules attenuates leukocyte infiltration in the small intestine of thermally injured mice. METHODS: Thirty-six mice were assigned to four groups. Mice in the sham group (n = 9) were underwent to sham thermal injury; mice in the burn group (n = 9) received 15% total body surface area full-thickness thermal injury; mice in the burn + CORM-2 group (n = 9) were underwent to the same thermal injury with immediate administration of tricarbonyldichlororuthenium (II) dimer CORM-2 (8 mg/kg, i.v.); and mice in the burn+DMSO group (n = 9) were underwent to the same thermal injury with immediate administration of 160 muL bolus injection of 0.5% DMSO/saline. Histological alterations and granulocyte infiltration of the small intestine were assessed. Polymorphonuclear neutrophil (PMN) accumulation (myeloperoxidase assay) was assessed in mice mid-ileum. Activation of nuclear factor (NF)-kappa B, expression levels of intercellular adhesion molecule-1 (ICAM-1) and inducible heme oxygenase in mid-ileum were assessed. RESULTS: Treatment of thermally injured mice with CORM-2 attenuated PMN accumulation and prevented activation of NF-kappa B in the small intestine. This was accompanied by a decrease in the expression of ICAM-1. In parallel, burn-induced granulocyte infiltration in mid-ileum was markedly decreased in the burn mice treated with CORM-2. CONCLUSION: CORM-released CO attenuates leukocyte infiltration in the small intestine of thermally injured mice by interfering with NF-kappa B activation and protein expression of ICAM-1, and therefore suppressing the pro-adhesive phenotype of endothelial cells.

[The inhibitory effects of extrinsic carbon monoxide-releasing molecules II on inflammatory responses in liver of mice with severe burns].

OBJECTIVE: To investigate the inhibitory effects of extrinsic carbon monoxide-releasing molecules II on inflammatory responses in liver of mice with severe burns and its potential mechanisms. METHODS: Forty-five male C57BL/6 mice were randomly divided into sham (simulation of burn with 37 degrees C warm water), sham + CORM-2 (with 8 mg/kg CORM-2 after the same manipulation as sham group), burn (with 15% TBSA full-thickness burns), burn + CORM-2 (with 8 mg/kg CORM-2 after the same manipulation as burn group), burn + DMSO (with DMSO after the same treatment as burn group) groups,with 9 mice in each group. The serum level of ALT and AST were determined at 24 post-burn hours (PBH), and the level of myeloperoxidase (MPO), nuclear factor (NF) kappaB, intercellular adhesion molecular (ICAM-1), vascular cell adhesion molecular (VCAM-1), as well as adhesion of polymorphonuclear leucocytes to sinusoidal endothelial cells (HSECs) after serum stimulation were detected and assessed at the same time-points. RESULTS: The level of ALT and AST (398 +/- 34,122 +/- 22 ), the activity of MPO and NF-kappaB, the protein level of ICAM-1 and VCAM-1 in burn group were obviously increased when compared with those in sham group and burn + CORM-2 group (P < 0.05 or P < 0.01). Additionally, the adhesion of PMN on HSEC after stimulation of serum in burn group was enhanced, while it was markedly inhibited after stimulation of serum in burn + CORM-2 group (P < 0.05). CONCLUSION: Extrinsic CORM-2 exhibits the ability to inhibit NF-kappaB activity, reduces the hepatic expression of ICAM-1 and VCAM-1, thereby alleviating sequestration of leukocytes after severe burns, so that hepatic inflammatory response is ameliorated, and liver function is improved.

Role of CO-releasing molecules liberated CO in attenuating leukocytes sequestration and inflammatory responses in the lung of thermally injured mice.

BACKGROUND: Acute lung injury and pulmonary inflammatory responses are important complications most frequently encountered in severely burned patients. Polymorphonuclear leukocyte (PMN) sequestration and the subsequent generation of oxidants and inflammatory mediators play the key roles in the pathogenesis of acute lung injury. In this study, we used CO-releasing molecules (CORM-2) to determine whether the CO-releasing molecules-liberated CO could attenuate leukocytes sequestration and the inflammatory response in the lung of thermally injured mice. MATERIALS AND METHODS: Fifty-four mice were assigned to three groups in three respective experiments. In each experiment, mice in sham group (n=6) underwent sham thermal injury, whereas mice in the burn group (n=6) received 15% total body surface area (TBSA) full-thickness thermal injury and mice in CORM-2 group (n=6) underwent the same thermal injury with immediate administration of CORM-2 (8 mg/kg, i.v.). PMN accumulation (MPO assay) in mice lungs and tumor necrosis factor-alpha and interleukin-1beta in BAL fluid, pulmonary edema formation, and wet/dry weight ratios of lung were determined. Activation of NF-kappaB and expression level of ICAM-1 in the lung was assessed. In in vitro experiment, PMN adhesion to experimental mice serum-stimulated mouse lung endothelial cells (MLEC) was assessed. RESULTS: Treatment of thermally injured mice with CORM-2 attenuated PMN accumulation and prevented activation of NF-kappaB in the lung. This was accompanied by a decrease of the expression of ICAM-1. In parallel, PMN adhesion to MLEC stimulated by CORM-2-treated thermally injured mice serum was markedly decreased. Also, CORM-2 markedly decreased the production of inflammatory mediators in BAL fluid without suppressing the permeability of pulmonary microcirculation. CONCLUSIONS: CORM-released CO attenuates the inflammatory response in the lung of thermally injured mice by decreasing leukocyte sequestration and interfering with NF-kappaB activation, protein expression of ICAM-1, and therefore, suppressing endothelial cells' pro-adhesive phenotype.