Fe/Cu MOFs of Fe2+-rich and Cu-doping via in situ reduction as nanozyme for peroxidase-like catalycity enhancement.

Fe-MOFs of mixed valence was synthesized by a solvothermal method via the in-situ reduction of ethylene glycol (EG) pre-coordination with the proper ratio of Fe2+/Fe3+ between 0.83 and 2.46. Synchronously with copper introduction, the Fe/Cu MOFs of mixed valence (Fe/Cu-MVMOFs) was then one pot acquired to remarkably improve the affinity of Fe2+ and Cu+ to H2O2 and promote the conversion efficiency of Fe2+/Fe3+ via the electron transfer among Fe-Cu bimetal clusters (XPS and XRD). Hence, the maximum reaction rate of H2O2 with Fe/Cu-MVMOFs reached 16.65 M·s-1, along with Km as low as 0.0479 mM. H2O2 and glutathione (GSH) were efficiently detected, ranging from 0.25 to 60 µM and from 0.2 to 40 µM, respectively. The investigation of catalyzation selectivity and practical serum detection by Fe/Cu-MVMOFs illustrated the efficacy and efficiency, denoting Fe/Cu-MVMOFs as the promising peroxidase candidate.

Continuous Covalent Organic Frameworks Membranes: From Preparation Strategies to Applications.

Covalent organic frameworks (COFs) are porous crystalline polymeric materials formed by the covalent bonding of organic units. The abundant organic units library gives the COFs species diversity, easily tuned pore channels, and pore sizes. In addition, the periodic arrangement of organic units endows COFs regular and highly connected pore channels, which has led to the rapid development of COFs in membrane separations. Continuous defect-free and high crystallinity of COF membranes is the key to their application in separations, which is the most important issue to be addressed in the research. This review article describes the linkage types of covalent bonds, synthesis methods, and pore size regulation strategies of COFs materials. Further, the preparation strategies of continuous COFs membranes are highlighted, including layer-by-layer (LBL) stacking, in situ growth, interfacial polymerization (IP), and solvent casting. The applications in separation fields of continuous COFs membranes are also discussed, including gas separation, water treatment, organic solvent nanofiltration, ion conduction, and energy battery membranes. Finally, the research results are summarized and the future prospect for the development of COFs membranes are outlined. More attention may be paid to the large-scale preparation of COFs membranes and the development of conductive COFs membranes in future research.

Enhancing Electron Conductivity and Electron Density of Single Atom Based Core-Shell Nanoboxes for High Redox Activity in Lithium Sulfur Batteries.

Herein, an integrated structure of single Fe atom doped core-shell carbon nanoboxes wrapped by self-growing carbon nanotubes (CNTs) is designed. Within the nanoboxes, the single Fe atom doped hollow cores are bonded to the shells via the carbon needles, which act as the highways for the electron transport between cores and shells. Moreover, the single Fe atom doped nanobox shells is further wrapped and connected by self-growing carbon nanotubes. Simultaneously, the needles and carbon nanotubes act as the highways for electron transport, which can improve the overall electron conductivity and electron density within the nanoboxes. Finite element analysis verifies the unique structure including both internal and external connections realize the integration of active sites in nano scale, and results in significant increase in electron transfer and the catalytic performance of Fe-N4 sites in both Li2 Sn lithiation and Li2 S delithiation. The Li-S batteries with the double-shelled single atom catalyst delivered the specific capacity of 702.2 mAh g-1 after 550 cycles at 1.0 C. The regional structure design and evaluation method provide a new strategy for the further development of single atom catalysts for more electrochemical processes.

Chronological and Carbohydrate-Dependent Transformation of Fatty Acids in the Larvae of Black Soldier Fly Following Food Waste Treatment.

Although black soldier fly larvae (BSFL) can convert food waste into insectile fatty acids (FAs), the chronological and diet-dependent transformation of larval FAs has yet to be determined. This study focused on the dynamics of larval FA profiles following food waste treatment and characterized factors that may drive FA composition and bioaccumulation. Larval FA matters peaked on Day 11 as 7.7 ± 0.7% of food waste dry matter, maintained stably from Day 11-19, and decreased slightly from Day 19-21. The BSFL primarily utilized waste carbohydrates for FA bioconversion (Day 0-11) and shifted to waste FAs (Day 7-17) when the carbohydrates were close to depletion. The optimal time window for larvae harvest was Days 17-19, which fulfilled both targets of waste oil removal and larval FA transformation. Larval FAs were dominated by C12:0, followed by C18:2, C18:1, and C16:0. The waste-reducing carbohydrate primarily accounted for larval FA bioaccumulation (r = -0.947, p < 0.001). The increase in diet carbohydrate ratio resulted in the elevation of larval C12:0 yield, which indicated that larval C12:0-FA was primarily biosynthesized from carbohydrates and further transformed from ≥C16 FAs. This study elucidates the bioaccumulation process of larval FAs for food waste treatment and highlights the importance of waste carbohydrates for both the composition and transformation of larval FAs.

Bio-Derived and Cost-Effective Membranes with High Selectivity for Redox Flow Batteries Based on Host-Guest Chemistry.

Redox flow batteries (RFBs) stand out as a promising energy storage system to solve the grid interconnection problems of renewable energy. Membranes play a critical role in regulating the performance of RFBs, and the selectivity is commonly controlled via either size exclusion or Donnan exclusion. Membranes typically account for 40% of the stack cost of RFBs, and it is essential to develop cost-effective membranes with high selectivity to achieve widespread application. Here, a type of membrane composed of highly abundant materials derived in nature, based on a scalable fabrication process, is reported. Moreover, high selectivity is achieved attributed to the host-guest interactions between membranes and redox species, which effectively alleviate the crossover of redox-active molecules. By incorporating starch into a chitosan matrix for zinc-iodine RFBs, the highly selective recognition of starch and chitosan (host) toward triiodide (guest) builds a "wall" to block the triiodide-based active materials, meanwhile, the conducting properties of such a membrane are not compromised. The proof-of-concept battery delivers a Coulombic efficiency of 98.6% and energy efficiency of 77.4% at a current density of 80 mA cm-2 , showing the promise of such a novel and cost-effective membrane design beyond traditional selectivity chemistry.

Layered Double Hydroxide-Assisted Fabrication of Prussian Blue Membranes for Precise Molecular Sieving.

Prussian Blue (PB), which was first discovered as robust blue-colored pigment in the year 1706, has shown promising prospects in disease treatment, energy conversion, water splitting, and sensing. Relying on the uniform 3.2 Å-sized pore channels as well as high stability in aqueous environments, in this study, we pioneered in situ preparation of polycrystalline PB membranes to justify their dye rejection and metal ion discrimination ability in aqueous environments. Among various factors, the introduction of calcined NiFe layered double hydroxide buffer layers on porous α-Al2 O3 substrates was found to play a paramount role in the formation of continuous polycrystalline PB membranes, thereby leading to excellent dye rejection efficiency (>99.0 %). Moreover, prepared PB membranes enabled discriminating different monovalent metal ions (e.g., Li+ , Na+ , and K+ ) depending on their discrepancy in Stokes diameters, showing great promise for lithium extraction from smaller-sized metal ions.

Hierarchically Porous C/Fe3C Membranes with Fast Ion-Transporting Channels and Polysulfide-Trapping Networks for High-Areal-Capacity Li-S Batteries.

We report here highly scalable yet stackable C/Fe3C membranes with fast ion-transport micro-/nanochannels and polysulfide-trapping networks via a facile phase-inversion process for high-areal-capacity Li-S batteries. The membrane cathodes with aligned channels and hierarchically porous networks significantly promote Li+ and electron transportation and meanwhile trap soluble polysulfide intermediates (LiPSs) effectively via strong chemical adsorption of the doped Fe3C nanoparticles in the membrane toward LiPSs. We further demonstrated that five-layer membrane electrodes with high S loading of 7.1 mg cm-2 were readily prepared via layer-by-layer stacking of the C/Fe3C membrane, which can deliver a high capacity of 726 mA h g-1 after 100 cycles, corresponding to an ultra-high-areal-capacity of 5.15 mA h cm-2 at a low electrolyte/sulfur (E/S) ratio of 6.4 µL mg-1. The scalable multifunctional membrane electrodes with excellent electrochemical performance under high-sulfur-loading and lean electrolyte conditions reveal its promising applications in practical Li-S batteries.

Scalable High-Areal-Capacity Li-S Batteries Enabled by Sandwich-Structured Hierarchically Porous Membranes with Intrinsic Polysulfide Adsorption.

The key to realizing practical applications of Li-S batteries lies in scalable fabrication of cathode materials with high sulfur-loading and strong binding of lithium polysulfides (LiPSs). We report a scalable CeO2-CNT@C porous membrane with a large porosity of 90%. Introducing CNTs is critical to increase the porosity and construct porous networks with CNTs as the skeleton and CeO2-doped carbon as the shell. The macropores can improve the transport of Li+ and electrolyte, while the porous networks possess high polysulfide-adsorbing and electron-transferring ability. The CeO2-CNT@C membrane can serve as an Al foil-free cathode and an interlayer for Li-S batteries. Moreover, CeO2 can immobilize LiPSs and can alleviate its shuttle effect. The Li-S batteries with a sulfur loading of 6.2 mg cm-2 deliver a capacity of 847 mA h g-1 after 100 cycles, showing a high areal capacity of 5.25 mA h cm-2 at a low electrolyte/sulfur ratio of 5.2 µL mg-1.

Co3O4 Nanosheets Preferentially Growing (220) Facet with a Large Amount of Surface Chemisorbed Oxygen for Efficient Oxidation of Elemental Mercury from Flue Gas.

Oxygen vacancies can capture and activate gaseous oxygen, forming surface chemisorbed oxygen, which plays an important role in the Hg0 oxidation process. Fine control of oxygen vacancies is necessary and a major challenge in this field. A novel method for facet control combined with morphology control was used to synthesize Co3O4 nanosheets preferentially growing (220) facet to give more oxygen vacancies. X-ray photoelectron spectroscopy (XPS) results show that the (220) facet has a higher Co3+/Co2+ ratio, leading to more oxygen vacancies via the Co3+ reduction process. Density functional theory (DFT) calculations confirm that the (220) facet has a lower oxygen vacancy formation energy. Furthermore, scanning electron microscopy (SEM) and transmission electron microscopy (TEM) results suggest that Co3O4 nanosheets yield more defects during the synthesis process. These results are the reasons for the greater number of oxygen vacancies in Co3O4 nanosheets, which is confirmed by electron energy loss spectroscopy (EELS), Raman spectroscopy, and photoluminescence (PL) spectroscopy. Therefore, Co3O4 nanosheets show excellent Hg0 removal efficiency over a wide temperature range of 100-350 °C at a high gas hourly space velocity (GHSV) of 180 000 h-1. Additionally, the catalytic efficiency of Co3O4 nanosheets is still greater than 83%, even after 80 h of testing, and it recovers to its original level after 2 h of in situ thermal treatment at 500 °C.

Long-term intervention of taurocholic acid over-expressing in cholestatic liver disease inhibits the growth of hepatoma cells.

Bile acids usually build up in patients with cholestatic liver disease. It was found that the concentration of taurocholic acid (TCA), one of the taurine conjugates of primary bile acids in serum, was elevated the most. While the role played by TCA in the disease is unclear, there is concern whether TCA contributes to the development of hepatocarcinoma from cholestasis. In the present study, the cell viability, flow cytometry, real-time polymerase chain reaction, intracellular ROS measurement, and intracellular Ca2+ measurement were used to investigate the effects of TCA on THLE-2 and HepG2 cells. The results showed that TCA is capable of inhibiting HepG2 cell growth whereas it has relatively little or no impact on that of THLE-2 cells until later stages of 16-day treatment. The growth inhibition is a result of cell apoptosis induced by the increase of Ca2+ and ROS level, and also associated with the increased expression of c-Myc, CEBPα, TNF-α, ICAM-1, VCAM-1, CXCL-2, Egr-1. HepG2 growth inhibition could contribute to the research on the treatment methods of patients already with hepatocarcinoma.

Constructing Patch-Ni-Shelled Pt@Ni Nanoparticles within Confined Nanoreactors for Catalytic Oxidation of Insoluble Polysulfides in Li-S Batteries.

Reducing the deposit of discharge products and suppressing the polysulfide shuttle are critical to enhancing reaction kinetics in Li-S batteries. Herein, a Pt@Ni core-shell bimetallic catalyst with a patch-like or complete Ni shell based on a confined catalysis reaction in porous carbon spheres is reported. The Pt nanodots can effectively direct and catalyze in situ reduction of Ni2+ ions to form core-shell catalysts with a seamless interface that facilitates the charge transfer between the two metals. Thus, the bimetallic catalysts offer a synergic effect on catalyzing reactions, which shows dual functions for catalytic oxidation of insoluble polysulfides to soluble polysulfides by effectively reducing the energy barrier with simultaneous strong adsorption, ensuring a high reversible capacity and cycling stability. A novel process based on the Pt@Ni core-shell bimetallic catalyst with a patch-like Ni shell is proposed: electronic migration from Ni to Pt forces Ni to activate Li2 S2 /Li2 S molecules by promoting the transformation of Li-S-Li to Ni-S-Li, consequently releasing Li+ and free electrons, simultaneously enhancing protonic/electronic conductivity. The presence of the intermediate state Ni-S-Li is more active to oxidize Li2 S to polysulfides. The Li2 S bound to adjacent Pt sites reacts with abundant -S-Li species and then releases the Pt sites for the next round of reactions.

Multishelled Transition Metal-Based Microspheres: Synthesis and Applications for Batteries and Supercapacitors.

With the rapid growth of material innovations, multishelled hollow nanostructures are of tremendous interest due to their unique structural features and attractive physicochemical properties. Continued effort has been made in the geometric manipulation, composition complexity, and construction diversity of this material, expanding its applications. Energy storage technology has benefited from the large surface area, short transport path, and excellent buffering ability of the nanostructures. In this work, the general synthesis of multishelled hollow structures, especially with architecture versatility, is summarized. A wealth of attractive properties is also discussed for a wide area of potential applications based on energy storage systems, including Li-ion/Na-ion batteries, supercapacitors, and Li-S batteries. Finally, the emerging challenges and outlook for multishelled hollow structures are mentioned.

Direct detection of SERCA calcium transport and small-molecule inhibition in giant unilamellar vesicles.

We have developed a charge-mediated fusion method to reconstitute the sarco/endoplasmic reticulum Ca2+-ATPase (SERCA) in giant unilamellar vesicles (GUV). Intracellular Ca2+ transport by SERCA controls key processes in human cells such as proliferation, signaling, and contraction. Small-molecule effectors of SERCA are urgently needed as therapeutics for Ca2+ dysregulation in human diseases including cancer, diabetes, and heart failure. Here we report the development of a method for efficiently reconstituting SERCA in GUV, and we describe a streamlined protocol based on optimized parameters (e.g., lipid components, SERCA preparation, and activity assay requirements). ATP-dependent Ca2+ transport by SERCA in single GUV was detected directly using confocal fluorescence microscopy with the Ca2+ indicator Fluo-5F. The GUV reconstitution system was validated for functional screening of Ca2+ transport using thapsigargin (TG), a small-molecule inhibitor of SERCA currently in clinical trials as a prostate cancer prodrug. The GUV system overcomes the problem of inhibitory Ca2+ accumulation for SERCA in native and reconstituted small unilamellar vesicles (SUV). We propose that charge-mediated fusion provides a widely-applicable method for GUV reconstitution of clinically-important membrane transport proteins. We conclude that GUV reconstitution is a technological advancement for evaluating small-molecule effectors of SERCA.

Structural characteristics of hydrated protons in the conductive channels: effects of confinement and fluorination studied by molecular dynamics simulation.

The relationship between the proton conductive channel and the hydrated proton structure is of significant importance for understanding the deformed hydrogen bonding network of the confined protons which matches the nanochannel. In general, the structure of hydrated protons in the nanochannel of the proton exchange membrane is affected by several factors. To investigate the independent effect of each factor, it is necessary to eliminate the interference of other factors. In this paper, a one-dimensional carbon nanotube decorated with fluorine was built to investigate the independent effects of nanoscale confinement and fluorination on the structural properties of hydrated protons in the nanochannel using classical molecular dynamics simulation. In order to characterize the structure of hydrated protons confined in the channel, the hydrogen bonding interaction between water and the hydrated protons has been studied according to suitable hydrogen bond criteria. The hydrogen bond criteria were proposed based on the radial distribution function, angle distribution and pair-potential energy distribution. It was found that fluorination leads to an ordered hydrogen bonding structure of the hydrated protons near the channel surface, and confinement weakens the formation of the bifurcated hydrogen bonds in the radial direction. Besides, fluorination lowers the free energy barrier of hydronium along the nanochannel, but slightly increases the barrier for water. This leads to disintegration of the sequential hydrogen bond network in the fluorinated CNTs with small size. In the fluorinated CNTs with large diameter, the lower degree of confinement produces a spiral-like sequential hydrogen bond network with few bifurcated hydrogen bonds in the central region. This structure might promote unidirectional proton transfer along the channel without random movement. This study provides the cooperative effect of confinement dimension and fluorination on the structure and hydrogen bonding of the slightly acidic water in the nanoscale channel.

Activation of the Solid Silica Layer of Aerosol-Based C/SiO2 Particles for Preparation of Various Functional Multishelled Hollow Microspheres.

Double-shelled C/SiO2 hollow microspheres with an outer nanosheet-like silica shell and an inner carbon shell were reported. C/SiO2 aerosol particles were synthesized first by a one-step rapid aerosol process. Then the solid silica layer of the aerosol particles was dissolved and regrown on the carbon surface to obtain novel C/SiO2 double-shelled hollow microspheres. The new microspheres prepared by the facile approach possess high surface area and pore volume (226.3 m(2) g(-1), 0.51 cm(3) g(-1)) compared with the original aerosol particles (64.3 m(2) g(-1), 0.176 cm(3) g(-1)), providing its enhanced enzyme loading capacity. The nanosheet-like silica shell of the hollow microspheres favors the fixation of Au NPs (C/SiO2/Au) and prevents them from growing and migrating at 500 °C. Novel C/C and C/Au/C (C/Pt/C) hollow microspheres were also prepared based on the hollow nanostructure. C/C microspheres (482.0 m(2) g(-1), 0.92 cm(3) g(-1)) were ideal electrode materials. In particular, the Au NPs embedded into the two carbon layers (C/Au/C, 431.2 m(2) g(-1), 0.774 cm(3) g(-1)) show a high catalytic activity and extremely chemical stability even at 850 °C. Moreover, C/SiO2/Au, C/Au/C microspheres can be easily recycled and reused by an external magnetic field because of the presence of Fe3O4 species in the inner carbon shell. The synthetic route reported here is expected to simplify the fabrication process of double-shelled or yolk-shell microspheres, which usually entails multiple steps and a previously synthesized hard template. Such a capability can facilitate the preparation of various functional hollow microspheres by interfacial design.

Shape-Controlled Synthesis of Magnetic Iron Oxide@SiO2-Au@C Particles with Core-Shell Nanostructures.

The preparation of nonspherical magnetic core-shell nanostructures with uniform sizes still remains a challenge. In this study, magnetic iron oxide@SiO2-Au@C particles with different shapes, such as pseduocube, ellipsoid, and peanut, were synthesized using hematite as templates and precursors of magnetic iron oxide. The as-obtained magnetic particles demonstrated uniform sizes, shapes, and well-designed core-shell nanostructures. Transmission electron microscopy (TEM) and energy dispersive X-ray spectroscopy (EDX) analysis showed that the Au nanoparticles (AuNPs) of ∼6 nm were uniformly distributed between the silica and carbon layers. The embedding of the metal nanocrystals into the two different layers prevented the aggregation and reduced the loss of the metal nanocrystals during recycling. Catalytic performance of the peanut-like particles kept almost unchanged without a noticeable decrease in the reduction of 4-nitrophenol (4-NP) in 8 min even after 7 cycles, indicating excellent reusability of the particles. Moreover, the catalyst could be readily recycled magnetically after each reduction by an external magnetic field.

Multi-heterostructured MXene/NiS2/Co3S4 with S-Vacancies to Promote Polysulfide Conversion in Lithium-Sulfur Batteries.

The severe shuttle effect of polysulfides (LiPSs) and the slow liquid-solid phase conversion are the main obstacles hindering the practical application of lithium-sulfur (Li-S) batteries. Separator modification with a high-activity catalyst can boost LiPSs conversion and suppress their shuttle effect. In this work, multi-heterostructured MXene/NiS2/Co3S4 with rich S-vacancies was constructed facilely with a hydrothermal and high-temperature annealing strategy for separator modification. The MXene sheet not only provides a physical barrier but also ensures a high conductivity and adsorption capacity of the catalyst; the dual active centers of NiS2 and Co3S4 catalyze LiPSs conversion. In addition, the vacancies and heterostructures can modulate the electronic structure of the catalyst, improve its intrinsic activity, and reduce the polysulfides reaction barrier, thus facilitating ion/electron transport and inhibiting the shuttle effect. Benefiting from these advantages, the Li-S battery with MXene/NiS2/Co3S4 modified separator exhibits exciting discharge capacities (1495.4 mAh g-1 at 0.1C and 549.0 mAh g-1 at 6C) and an excellent ultra-long cycle life (average capacity decay rate of 0.026% for 2000 cycles at 2C); at a high sulfur loading of 10.0 mg cm-2, the battery operates for nearly 80 cycles at 0.2C, giving a capacity retention rate of 75.76%. This work provides a high-activity catalyst for Li-S batteries.

Confined liquid crystallization governed by electric field for API crystal polymorphism screening and massive preparation.

Active pharmaceutical ingredients (APIs) crystal preparation is a significant issue for the pharmaceutical development attributed to the effect on anti-inflammatory, anti-bacteria, and anti-viral, etc. While, the massive preparation of API crystal with high polymorphism selectivity is still a pendent challenge. Here, we firstly proposed a criterion according to the molecular aggregation, molecular orientation, and hydrogen bond energy between INA molecules from molecular dynamics (MD) simulations, which predicted the hydrogen bond architecture in crystal under different electric fields, hinting the recognition of crystal polymorphism. Then, an electric field governing confined liquid crystallization was constructed to achieve the INA crystal polymorphism screening relying on the criterion. Further, magnifying confined liquid volume by 5000 times from 1.0 µL to 5.0 mL realized the massive preparation of INA crystal with high polymorphic purity (>98.4%), giving a unique pathway for crystal engineering and pharmaceutical industry on the development of innovative and generic API based drugs.

Regulation of Hard Segment Cluster Structures for High-performance Poly(urethane-urea) Elastomers.

Elastomers are widely used in daily life; however, the preparation of degradable and recyclable elastomers with high strength, high toughness, and excellent crack resistance remains a challenging task. In this report, a polycaprolactone-based poly(urethane-urea) elastomer is presented with excellent mechanical properties by optimizing the arrangement of hard segment clusters. It is found that long alkyl chains of the chain extenders lead to small and evenly distributed hard segment clusters, which is beneficial for improving mechanical properties. Together with the multiple hydrogen bond structure and stress-induced crystallization, the obtained elastomer exhibits a high strength of 63.3 MPa, an excellent toughness of 431 MJ m-3 and an outstanding fracture energy of 489 kJ m-2, while maintaining good recyclability and degradability. It is believed that the obtained elastomer holds great promise in various application fields and it contributes to the development of a sustainable society.

Hydrogel Nanoparticles Enable Nucleation Barrier Regulation and Ion Anchoring as an Alternative Pathway for Monosodium Urate Monohydrate Crystallization Control.

Gout flare-up, commonly resulting from monosodium urate monohydrate (MSUM) crystallization, has led to painful inflammatory arthritis among hundreds of millions of people. Herein, a kind of hydrogel nanoparticles (HNPs) with specific properties was developed, aimed at providing a promising pathway for MSUM crystallization control. The experimental and molecular dynamics simulation results synchronously indicate that the fabricated HNPs achieve efficient inhibition of MSUM crystallization governed by the mechanism of "host-guest interaction" even under very low-dose administration. HNPs as the host dispersed in the hyperuricemic model effectively lift the relative heterogeneous nucleation barrier of the MSUM crystal and hinder solute aggregation with strong electronegativity and hydrophobicity. The initial appearance of MSUM crystals was then delayed from 94 to 334 h. HNPs as the guest on the surface of the formed crystal can decelerate the growth rate by anchoring ions and occupying the active sites on the surface, and the terminal yield of the MSUM crystal declined to less than 1% of the control group. The good biocompatibility of HNPs (cell viability > 94%) renders it possible for future clinical applications. This study can guide the rational design of inhibitory nanomaterials and the development of their application in the control of relevant pathological crystallization.