Ionic Microenvironment Research Articles

CNS/PNS proteoglycans functionalize neuronal and astrocyte niche microenvironments optimizing cellular activity by preserving membrane polarization dynamics, ionic microenvironments, ion fluxes, neuronal activation, and network neurotransductive capacity.

Central and peripheral nervous system (CNS/PNS) proteoglycans (PGs) have diverse functional roles, this study examined how these control cellular behavior and tissue function. The CNS/PNS extracellular matrix (ECM) is a dynamic, responsive, highly interactive, space-filling, cell supportive, stabilizing structure maintaining tissue compartments, ionic microenvironments, and microgradients that regulate neuronal activity and maintain the neuron in an optimal ionic microenvironment. The CNS/PNS contains a high glycosaminoglycan content (60% hyaluronan, HA) and a diverse range of stabilizing PGs. Immobilization of HA in brain tissues by HA interactive hyalectan PGs preserves tissue hydration and neuronal activity, a paucity of HA in brain tissues results in a pro-convulsant epileptic phenotype. Diverse CS, KS, and HSPGs stabilize the blood-brain barrier and neurovascular unit, provide smart gel neurotransmitter neuron vesicle storage and delivery, organize the neuromuscular junction basement membrane, and provide motor neuron synaptic plasticity, and photoreceptor and neuron synaptic functions. PG-HA networks maintain ionic fluxes and microgradients and tissue compartments that contribute to membrane polarization dynamics essential to neuronal activation and neurotransduction. Hyalectans form neuroprotective perineuronal nets contributing to synaptic plasticity, memory, and cognitive learning. Sialoglycoprotein associated with cones and rods (SPACRCAN), an HA binding CSPG, stabilizes the inter-photoreceptor ECM. HSPGs pikachurin and eyes shut stabilize the photoreceptor synapse aiding in phototransduction and neurotransduction with retinal bipolar neurons crucial to visual acuity. This is achieved through Laminin G motifs in pikachurin, eyes shut, and neurexins that interact with the dystroglycan-cytoskeleton-ECM-stabilizing synaptic interconnections, neuronal interactive specificity, and co-ordination of regulatory action potentials in neural networks.

Spectrofluorometric determination of calcium in the human nasal secretions investigating the association with olfactory function

Ionic microenvironment of the nasal secretions especially calcium ions play essential role in the olfactory transmission. However, there is a critical need to determine the free calcium levels in healthy people's nasal secretions in contrast to those of patients with olfactory impairment. A selective spectrofluorometric method was created to quantify nasal calcium levels utilizing its quenching ability to the fluorescence of the functionalized carbon quantum dots. The surface of carbon quantum dots was functionalized with calcium ionophore A23187 and ion association complex, calcium phosphotungstate, to improve the selectively to quantify calcium ions. The functionalized carbon quantum dots exhibited a concentration-dependent fluorescence quenching upon interaction with calcium ions. Different factors influencing the quenching process were done to provide efficient analytical process. The new method, demonstrated accurate calcium determination over the concentration range of 200–4000 ng/mL. The suggested technique was used to measure the calcium in the nasal secretions of both healthy people and patients with olfactory impairment. The findings revealed significantly higher calcium levels in the patient with olfactory dysfunction (healthy vs. patient; 735 ± 20 ng/mL vs. 2987 ± 37 ng/mL, p < 0.05).

Integration of WOx/1D C3N4/2D C3N4 multi-junction through in-situ “PTA-Mel” ionic microenvironment for efficient aromatic wastes degradation via charge carrier separation improvement

High photogenerated carrier recombination inhibits the widespread application of graphite-phase carbon nitride (g-C3N4). Construction of junctions is an effective strategy but still under challenges, such as tedious procedure and limited efficiency. Herein, WOx/1D g-C3N4/2D g-C3N4 multi-junction with enhanced separation of photogenerated carriers was one-pot integrated through in-situ “PTA-Mel” ionic microenvironment by mixing phosphotungstic acid (PTA) and melamine (Mel). Protonated Mel by PTA contributed to the formation of 1D g-C3N4 and the decomposition of [P(W3O40)4]3- produced WOx. 1D g-C3N4 and WOx with oxygen-vacancy deficient provided channels and caves for photoelectrons transfer, respectively. Compared with pure g-C3N4, the degradation rate constants of Rh B and tetracycline hydrochloride (TC) by WOx/1D g-C3N4/2D g-C3N4 are 2.34 and 1.45 times high respectively due to the excellent visible light absorption and improved photogenerated carrier separation. This method could be extended to the design of multiple heterojunctions in one photocatalyst through a facile process.

Ion‐Engineered Microcryogels via Osteogenesis‐Angiogenesis Coupling and Inflammation Reversing Augment Vascularized Bone Regeneration

AbstractNative bone inherently requires a balanced ionic microenvironment to maintain bone homeostasis. Hence, scaffolds designed for the sustained release of therapeutic ions into bone defects hold great promise for bone regeneration. Magnesium (Mg) and silicon (Si) are essential elements, which play crucial roles in the process of bone regeneration, impacting immunomodulation, angiogenesis, and osteogenesis. Herein, porous cryogel‐type organic–inorganic composite microspheres are developed as injectable microscaffolds (denoted as GMN). GMN enables sustained release of Mg/Si ions at an optimized ratio, achieving the most significant synergistic effect on vascularized bone regeneration. Various conditioned media are obtained to explore angiogenesis‐osteogenesis coupling, as well as the crosstalk between bone marrow mesenchymal stromal cells (BMSCs) and macrophages. Meanwhile, autocrine and paracrine effects simultaneously play synergistic modulating functions in determining cell fates under the guidance of Mg/Si ions and biofactors secreted by cells. Overall, the Mg/Si ion‐engineering microscaffolds create a conducive microenvironment to efficiently augment the regeneration of vascularized bone tissue in vivo, offering a versatile platform for tissue engineering.

Differential effects of the lipidic and ionic microenvironment on NPP1's phosphohydrolase and phosphodiesterase activities

Ecto-nucleotide pyrophosphatase/phosphodiesterase 1 (NPP1) is an enzyme present in matrix vesicles (MV). NPP1 participates on the regulation of bone formation by producing pyrophosphate (PPi) from adenosine triphosphate (ATP). Here, we have used liposomes bearing dipalmitoylphosphatidylcholine (DPPC), sphingomyelin (SM), and cholesterol (Chol) harboring NPP1 to mimic the composition of MV lipid rafts to investigate ionic and lipidic influence on NPP1 activity and mineral propagation. Atomic force microscopy (AFM) revealed that DPPC-liposomes had spherical and smooth surface. The presence of SM and Chol elicited rough and smooth surface, respectively. NPP1 insertion produced protrusions in all the liposome surface. Maximum phosphodiesterase activity emerged at 0.082 M ionic strength, whereas maximum phosphomonohydrolase activity arose at low ionic strength. Phosphoserine-Calcium Phosphate Complex (PS-CPLX) and amorphous calcium-phosphate (ACP) induced mineral propagation in DPPC- and DPPC:SM-liposomes and in DPPC:Chol-liposomes, respectively. Mineral characterization revealed the presence of bands assigned to HAp in the mineral propagated by NPP1 harbored in DPPC-liposomes without nucleators or in DPPC:Chol-liposomes with ACP nucleators. These data show that studying how the ionic and lipidic environment affects NPP1 properties is important, especially for HAp obtained under controlled conditions in vitro.

Ionic Liquids Microenvironment Modulates the Interface Properties of g-C3N4 for Boosting the Performance of Photodegradation and Infected Wound-Healing Therapy.

The improvement of photocatalytic activity of g-C3N4 is expected for its advanced applications but remains a challenge due to the limitations of current strategies, such as single function, inefficiency, and uneconomical. Herein, a modified g-C3N4 with improved interface properties is constructed through the modulation of the ionic microenvironment affected by ionic liquids (ILs) and exhibits a 2.3-fold enhanced photodegradation efficiency and a 3.5-fold enhanced reaction rate relative to pristine g-C3N4. It has demonstrated excellent performance in photo-therapy bacterial-infected wounds. Theoretical calculation indicated that the precursor can be regulated by designing the specific ILs microenvironment to form "ILs-Mel" clusters due to the diversity of interaction energy and electrostatic potential. The cluster results in uneven stress on the 2D plane, further inducing the reconstruction of the microstructure. The synergistic effect of cations and anions of ILs on regulating the interface properties of g-C3N4 due to the change of skeleton structure during thermolysis of ILs. The microstructure, surface, and optical-electrical properties can be adjusted by selecting different cations of ILs, and the custom-made band structure and wettability can be obtained by selecting different anions. This work provides a facile strategy to modulate the interface properties of g-C3N4 by building specific a microenvironment of precursor.

The effect of a bionic bone ionic environment on osteogenesis, osteoimmunology, and in situ bone tissue engineering

Bone, a mineralized tissue, continuously undergoes remodeling. It is a process that engages the mineralization and demineralization of the bone matrix, orchestrated by the interactions among cells and cell-secreted biomolecules under the bone ionic microenvironment (BIE). The osteoinductive properties of the demineralized organic bone matrix and many biological factors have been well-investigated. However, the impact of the bone ionic environment on cell differentiation and osteogenesis remains largely unknown. In this study, we extracted and isolated inorganic bone components (bone-derived monetite, BM) using a low-temperature method and, for the first time, investigated whether the BIE could actively affect cell differentiation and regulate osteoimmune reactions. It was evidenced that the BIE could foster the osteogenesis of human bone marrow stromal cells (hBMSCs) and promote hBMSCs mineralization without using osteogenic inductive agents. Interestingly, it was noted that BIE resulted in intracellular mineralization, evidenced by intracellular accumulation of carbonate hydroxyapatite similar to that oberved in osteoblasts cultured in osteoinductive media.Additionally, BIE was found to enhance osteogenesis by generating a favorable osteoimmune environment. In a rat calvarial bone defect model, the osteogenic capacity of BIE was evaluated using a collagen type I-impregnated BM (Col-BM) composite. It showed that Col-BM significantly promoted new bone formation in the critical-size bone defect areas. Taken together, this is the first study that investigated the influence of the BIE on osteogenesis, osteoimmunology, and in situ bone tissue engineering. The innate osteoinductive potential of inorganic bone components, both in vitro and in vivo, not only expands the understanding of the BIE on osteogenesis but also benefits future biomaterials engineering for bone tissue regeneration.

Preparation of lithium-containing magnesium phosphate-based composite ceramics having high compressive strength, osteostimulation and proangiogenic effects

Fairly high concentrations of magnesium and lithium are conducive to improving the osteogenic and angiogenic capacities. In the current study, lithium-containing magnesium phosphate-based ceramics (AMP/LMPGs) were prepared from amorphous magnesium phosphate (AMP) at a low sintering temperature (650 °C), and the lithium/magnesium-containing phosphate glasses (LMPGs) were utilized as sintering additives. During the sintering procedure of AMP/LMPGs, the AMP reacted with LMPGs, producing new compounds. The AMP/LMPGs displayed nano-size grains and plentiful micropores. The addition of LMPGs noticeably increased the porosity as well as compressive strength of the AMP/LMPGs ceramics. The AMP/LMPGs sustainedly released Mg, P and Li ions, forming Mg-rich ionic microenvironment, which ameliorated cellular proliferation, osteogenic differentiation and proangiogenic capacities. The AMP/LMPGs ceramics with considerably high compressive strength, osteostimulation and proangiogenic effects were expected to efficiently regenerate the bone defects.

Effect of biocomposite mediated magnesium ionic micro-homeostasis on cell fate regulation and bone tissue regeneration

Bioinorganic cations, that actively involved in many vital cellular activities, have been highlighted in regeneration and repair of tissues recently. However, researchers are still exploring how the sophisticated regulation of these bioactive factors within the microenvironment contribute to the process. Here, we established magnesium oxide homogeneously- and heterogeneously-embedded biocomposites to investigate the biological impacts that result from the different aggregation structure of the bioinorganic element. On the heterogeneous biocomposite, unbalanced microenvironment with erratic ion niche was provided, while stable ionic microenvironment was shown on the homogeneous biocomposite. Compared with the ionic micro-homeostasis, the heterogeneous micron-cluster-created unbalanced niche compromised cellular adhesion and proliferation by restraining the membrane extensions and downregulating the expression of proliferative genes. This unbalanced niche also motivated nonactivated macrophage polarized towards pro-inflammatory phenotype and induced high ratio of necrotic cell death by increasing the intracellular oxidative stress and decreasing the ATP content. After implantation, the homogeneous scaffold promoted tissue healing, whereas the immune responses were deteriorated and prolonged by heterogeneous scaffold, which leading to impaired bone regeneration. This study demonstrated the importance of biocomposite-established magnesium ionic micro-homeostasis on bone tissue regeneration and may inspires the future development of biomaterials.

Neurofluids and the glymphatic system: anatomy, physiology, and imaging.

First described in 2012, the glymphatic system is responsible for maintaining homeostasis within the central nervous system, including nutrient delivery, waste clearance, and consistency of the ionic microenvironment. It is comprised of glial cells and barrier systems that modulate neurofluid production, circulation, and exchange. Experimental interrogation of neurofluid dynamics is restricted to ex vivo and in vitro studies in animals and humans, therefore diagnostic imaging plays an important role in minimally invasive evaluation. This review article will synthesize current knowledge and theories regarding neurofluid circulation and implications for neuroimaging. First, we will discuss the anatomy of the neurogliovascular unit, including paravascular and perivascular pathways of fluid exchange. In addition, we will summarize the structure and function of barrier systems including the blood-brain, blood-cerebrospinal fluid, and brain-cerebrospinal fluid barriers. Next, we will mention physiologic factors that yield normal variations in neurofluid circulation, and how various disease pathologies can disrupt glymphatic drainage pathways. Lastly, we will cover the spectrum of diagnostic imaging and interventional techniques with relevance to glymphatic structure, flow, and function. We conclude by highlighting current barriers and future directions for translational imaging and applications to neurologic disorders.

Multicellular Bioprinting of Biomimetic Inks for Tendon-to-Bone Regeneration.

Tendon-to-bone interface has a hierarchical structure and gradient component that are conducive to distributing the stresses to achieve movement. Conventional biomaterials lack the capacity to induce synchronous repair of multiple tissues, resulting in the failure of the interface repair. Biomimetic strategies have attracted enormous attention in the field of complex structure regeneration because they can meet the different physiological requirements of multiple tissues. Herein, a biomimetic ink mimicking tendon/bone tissues is developed by combining tendon/bone-related cells and Mo-containing silicate (MS) bioceramics. Subsequently, biomimetic multicellular scaffolds are fabricated to achieve the simulation of the hierarchical structure and cellular composition of tendon-to-bone interfaces by the spatial distribution of the biomimetic inks via 3D bioprinting, which is of great significance for inducing the regeneration of complex structures in the interface region. In addition, attributed to the desirable ionic microenvironment created by MS bioceramics, the biomimetic scaffolds possess the dual function of inducing tendon/bone-related cells tenogenic and osteogenic differentiation in vitro, and promote the integrated regeneration of tendon-to-bone interfaces in vivo. The study offers a feasible strategy to construct biomimetic multicellular scaffolds with bifunction for inducing multi-lineage tissue regeneration, especially for regenerating soft-to-hard tissue interfaces.

Post-traumatic Stress Disorder: Focus on Neuroinflammation.

Post-traumatic stress disorder (PTSD), gaining increasing attention, is a multifaceted psychiatric disorder that occurs following a stressful or traumatic event or series of events. Recently, several studies showed a close relationship between PTSD and neuroinflammation. Neuroinflammation, a defense response of the nervous system, is associated with the activation of neuroimmune cells such as microglia and astrocytes and with changes in inflammatory markers. In this review, we first analyzed the relationship between neuroinflammation and PTSD: the effect of stress-derived activation of the hypothalamic-pituitary-adrenal (HPA) axis on the main immune cells in the brain and the effect of stimulated immune cells in the brain on the HPA axis. We then summarize the alteration of inflammatory markers in brain regions related to PTSD. Astrocytes are neural parenchymal cells that protect neurons by regulating the ionic microenvironment around neurons. Microglia are macrophages of the brain that coordinate the immunological response. Recent studies on these two cell types provided new insight into neuroinflammation in PTSD. These contribute to promoting comprehension of neuroinflammation, which plays a pivotal role in the pathogenesis of PTSD.

Enhancement of critical-sized bone defect regeneration by magnesium oxide-reinforced 3D scaffold with improved osteogenic and angiogenic properties

• 3D bio-nanocomposite scaffold which have an ideal magnesium ionic microenvironment was developed for critical-sized bony tissue repairing. • Significantly enhanced osteogenic effects were observed over the bio-nanocomposite as compare to the polycaprolactone control. • The rodent femoral and critical-sized cranial defect models were applied to characterize the osteogenesis in vivo . • Magnesium enriched scaffold exhibited remarkably increased bone volume, enhanced angiogenesis, and almost recovered critical-sized defect after an 8-week implantation. The healing of critical-sized bone defects (CSD) remains a challenge in orthopaedic medicine. In recent years, scaffolds with sophisticated microstructures fabricated by the emerging three-dimensional (3D) printing technology have lighted up the treatment of the CSD due to the elaborate microenvironments and support they may build. Here, we established a magnesium oxide-reinforced 3D-printed biocomposite scaffold to investigate the effect of magnesium-enriched 3D microenvironment on CSD repairing. The composite was prepared using a biodegradable polymer matrix, polycaprolactone (PCL), and the dispersion phase, magnesium oxide (MgO). With the appropriate surface treatment by saline coupling agent, the MgO dispersed homogeneously in the polymer matrix, leading to enhanced mechanical performance and steady release of magnesium ion (Mg 2+ ) for superior cytocompatibility, higher cell viability, advanced osteogenic differentiation, and cell mineralization capabilities in comparison with the pure PCL. The in-vivo femoral implantation and critical-sized cranial bone defect studies demonstrated the importance of the 3D magnesium microenvironment, as a scaffold that released appropriate Mg 2+ exhibited remarkably increased bone volume, enhanced angiogenesis, and almost recovered CSD after 8-week implantation. Overall, this study suggests that the magnesium-enriched 3D scaffold is a potential candidate for the treatment of CSD in a cell-free therapeutic approach.

The Localized Ionic Microenvironment in Bone Modelling/Remodelling: A Potential Guide for the Design of Biomaterials for Bone Tissue Engineering

Bone is capable of adjusting size, shape, and quality to maintain its strength, toughness, and stiffness and to meet different needs of the body through continuous remodeling. The balance of bone homeostasis is orchestrated by interactions among different types of cells (mainly osteoblasts and osteoclasts), extracellular matrix, the surrounding biological milieus, and waste products from cell metabolisms. Inorganic ions liberated into the localized microenvironment during bone matrix degradation not only form apatite crystals as components or enter blood circulation to meet other bodily needs but also alter cellular activities as molecular modulators. The osteoinductive potential of inorganic motifs of bone has been gradually understood since the last century. Still, few have considered the naturally generated ionic microenvironment's biological roles in bone remodeling. It is believed that a better understanding of the naturally balanced ionic microenvironment during bone remodeling can facilitate future biomaterial design for bone tissue engineering in terms of the modulatory roles of the ionic environment in the regenerative process.

Osteogenic capacity of octacalcium phosphate involving macrophage polarization.

Previous research has found that octacalcium phosphate (OCP) increases macrophage accumulation and alters the initial inflammatory response. However, the role of the immune response induced by OCP in osteogenesis remains unknown. This study investigated the behavior of macrophages and bone regeneration capacity during the early inflammatory stage of OCP-mediated osteogenesis. To assess the change in macrophage polarization and osteogenic capacity, we used a standardized rat defect model filled with OCP or calcium-deficient hydroxyapatite (CDHA)-a material obtained through the hydrolysis of the original OCP. OCP or CDHA granules were incubated with RAW264 cells for 5 days to investigate the effect of physicochemical characteristics on macrophage cytokine/chemokine expression in vitro. Our in vivo results show that due to the OCP implantation, macrophages in the rat tibial defect area tend to polarize to the M2 phenotype (anti-inflammatory) and inhibit the formation of the M1 phenotype (pro-inflammatory). In comparison to CDHA, OCP exhibited superior bone regeneration potential due to its rapid promotion of cortical bone healing and stimulation of macrophage-related growth factors. Furthermore, our in vitro results have shown that OCP regulates the expression of macrophage chemokines over time. Compared to incubation with CDHA, incubation with OCP caused changes in the ionic microenvironment. These findings suggest that the OCP-mediated macrophage polarization and secretion profile not only regulate immune function but also positively affect osteogenesis.

Sodium channels and the ionic microenvironment of breast tumours.

Cancers of epithelial origin such as breast, prostate, cervical, gastric, colon and lung cancer account for a large proportion of deaths worldwide. Better treatment of metastasis, the main cause of cancer deaths, is therefore urgently required. Several of these tumours have been shown to have an abnormally high concentration of Na+ ([Na+ ]) and emerging evidence points to this accumulation being due to elevated intracellular [Na+ ]. This poses intriguing questions about the cellular mechanisms underlying Na+ dysregulation in cancer, and its pathophysiological significance. Elevated intracellular [Na+ ] may be due to alterations in activity of the Na+ /K+ -ATPase, and/or increased influx via Na+ channels and Na+ -linked transporters. Maintenance of the electrochemical Na+ gradient across the plasma membrane is vital to power many cellular processes that are highly active in cancer cells, including glucose and glutamine import. Na+ channels are also upregulated in cancer cells, which in turn promotes tumour growth and metastasis. For example, ENaC and ASICs are overexpressed in cancers, increasing invasion and proliferation. In addition, voltage-gated Na+ channels are also upregulated in a range of tumour types, where they promote metastatic cell behaviours via various mechanisms, including membrane potential depolarisation and altered pH regulation. Together, recent findings relating to elevated Na+ in the tumour microenvironment and how this may be regulated by several classes of Na+ channels provide a link between altered Na+ handling and poor clinical outcome. There are new opportunities to leverage this altered Na+ microenvironment for therapeutic benefit, as exemplified by several ongoing clinical trials.

Circular adsorptive utilization of benzalkonium chloride via construction of ionic microenvironment in dopamine quinone-functionalized acrylic fiber surface

A novel dopamine quinone-functionalized acrylic fiber (PANdpqF) was successfully synthesized, which adsorbed the disinfectant dodecyl dimethyl benzyl ammonium chloride (DDBAC) to in-situ construct a highly efficient catalyst (DDBAC@PANdpqF) for the cyclization of CO2 with epoxide. The successful preparation of PANdpqF was proved by 13C Cross Polarization-Magic Angle Spinning nuclear magnetic resonance, X-ray photoelectron spectroscopy, Fourier transform infrared, and scanning electron microscopy. High adsorption capacity of DDBAC on PANdpqF has been demonstrated by ultraviolet analysis, and the theoretical maximum adsorption capacity was calculated as 666.67 mg/g. Based on comprehensive analysis, the corresponding adsorption mechanism is proposed in which chloride ion of DDBAC is added to o-quinone moiety through Michael addition, followed by the formation of phenoxy and quaternary ammonium ion pair. DDBAC@PANdpqF was well applicable to catalyze the cyclization of CO2, and the yield could reach 93.7% even with a low catalyst loading. The possible cooperatively catalytic mechanism was proposed correspondingly, in which phenolic hydroxyl helps to activate CO2 and epoxide, phenoxy anion attacks CO2 as a nucleophile, and quaternary ammonium cation stabilizes the anionic intermediates. Overall, the functionalized acrylic fiber adsorbed environmentally harmful disinfectant DDBAC to furnish a highly active catalyst for the transformation of greenhouse gas CO2 into useful carbonates, which provides a new method for advanced environmental pollution control.

Insulin biomolecular condensate formed in ionic microenvironment modulates the structural properties of pristine and magnetic cellulosic nanomaterials

The study reports the formation of a unique molecular condensate of insulin molecules with Zn2+ at a molar ratio of 1:1 under thermal stress. The condensate was cross-linked, viscoelastic, and structurally reversible by pH modulation. This unique state was formed by isoelectric condensation of insulin conformational variants (CVs) through helix unwinding, random coil relaxation, and subsequently transition to a β-sheet rich aggregate-like structure. The ions (Na+, Cl- and Zn2+) were found to promote the macromolecular organization through localized ionic interactions. Interestingly, this viscous aggregate instantaneously dissolved upon pH reduction, releasing monomeric insulin. Next, large-length cellulose nanofibers (CNF) and rod-shaped Fe-functionalized cellulose nanocrystals (Fe-CNC) were independently co-incubated with [Zn2+]:[Insulin]. The micrometer-length CNFs were reduced to short-length cellulose nanorods (CNRs), whereas, Fe-CNCs were reduced to ultrathin nanothreads which interacted together and formed spherical Fe-CNCs within insulin microspheres. The CNR-Ins condensate and Fe-CNC-Ins microsphere promoted the adhesion and growth of BHK-21 cells by 74.5 % and 72.6 %, respectively. This unique insulin condensate and its specialized hybrid structures might have an enormous impact on material science.

Redox Mediator with the Function of Intramolecularly Disproportionating Superoxide Intermediate Enabled High‐Performance Li–O2 Batteries

AbstractThe large charge overpotential and poor cycling stability triggered by sluggish Li2O2 oxidation kinetics and severe superoxide‐related side reactions greatly restrict the development and application of lithium–oxygen batteries. Finding out high‐efficiency catalysts that can effectively facilitate a highly reversible formation/decomposition of lithium peroxide is still a crucial challenge in the field of Li–O2 batteries. Herein, a soluble catalyst of 2,2'‐Azino‐bis(3‐ethylbenzothiazoline‐6‐sulfonic acid) diammonium salt (ABTS) that can promote highly reversible formation and decomposition of Li2O2 during discharge and charge processes is reported for the first time. During discharge, it can capture and couple two LiO2 intermediates via its sulfonate and ammonium ions, and induce the intramolecular disproportionation reaction to produce Li2O2 through ionic microenvironment, which not only prompts the solution‐phase growth of Li2O2, but also restricts the reactivity of LiO2 intermediate, thus significantly alleviating the electrode surface passivation issue and suppressing the superoxide‐related side reactions. During charge, it can quickly transport electrons between the electrode and Li2O2 by serving as a new kind of redox mediator (RM), thus greatly facilitating the Li2O2 oxidation kinetics. As a result, the Li–O2 batteries that incorporate ABTS exhibit outstanding electrochemical performance, low charge overpotential, high discharge capacity, and high cycling stability.

Ionic microenvironment constructed in quaternary ammonium modified polyacrylonitrile fiber for efficient CO2 fixation

Fiber-supported quaternary ammonium catalysts for the fixation of CO2 with epoxides were designed and prepared via amination and quaternization of polyacrylonitrile fiber, followed by ion exchange with different anions. The impact of different quaternary ammonium structures and counter anions on the reaction yields was investigated. A fiber catalyst (PANT-UdAF-I) with a C11 carboxylic acid chain and iodide counter anion exhibited excellent catalytic activity in the fixation of CO2 with epoxides under mild and solvent-free conditions (80 °C, 0.1 MPa) with a very low catalyst amount (0.5 mol%), and diverse cyclic carbonates were obtained in yields between 24–99 %. PANT-UdAF-I could be conveniently separated by filtration and showed good recyclability and durability till the 4th cycle. Novel cooperative catalytic mechanism is proposed where the ionic microenvironment plays a crucial role to stabilize the ionic intermediates and lowers the activation energy of the reaction.