Transferrin-mediated increase of labile iron Pool following simulated ischemia causes lipid peroxidation during the early phase of reperfusion

Heart ischemia/reperfusion (I/R) injury is related to iron content. However, the occurrence and mechanism of changes in labile iron pool (LIP) during I/R is debatable. Moreover, the identity of the iron form dominant in LIP during I/R is unclear. Herein, we measured changes of LIP during simulated ischemia (SI) and reperfusion (SR), in which ischemia was simulated in vitro with lactic acidosis and hypoxia. Total LIP did not change in lactic acidosis, whereas LIP, especially Fe3+, increased in hypoxia. Under SI, accompanied by hypoxia with acidosis, both Fe2+ and Fe3+ were significantly increased. Increased total LIP was maintained at 1 h post-SR. However, the Fe2+ and Fe3+ portion was changed. The increased Fe2+ was decreased, and conversely the Fe3+ was increased. BODIPY oxidized signal increased and through the time-course these changes correlated with blebbing of cell membrane and SR-induced LDH release. These data suggested lipid peroxidation occurred via Fenton’s reaction. The experiments using bafilomycin A1 and zinc protoporphyrin suggested no role of ferritinophagy or heme oxidation in the increase of LIP during SI. The extracellular source, transferrin assessed using serum transferrin bound iron (TBI) saturation showed that the depletion of TBI reduced SR-induced cell damages and additive saturation of TBI accelerated SR-induced lipid peroxidation. Furthermore, Apo-Tf dramatically blocked the increase of LIP and SR-induced damages. In conclusion, Tf-mediated iron induces the increase of LIP during SI, and it causes Fenton reaction-mediated lipid peroxidation during the early phase of SR.</p

Ice-Templated Bimodal-Porous Silver Nanowire/PDMS Nanocomposites for Stretchable Conductor

A three-dimensional (3D) bimodal-porous silver nanowire (AgNW) nanostructure with superior electrical properties is fabricated by freeze drying of AgNW aqueous dispersion with macrosized ice spheres for bimodal-porous structure. The ice sphere dispersed AgNW solution yields a 3D AgNW network at the surface of ice sphere and formation of macropores by removal of ice sphere during freeze-drying process. The resulting nanostructures exhibit excellent electrical properties due to their low electrical percolation threshold by the formation of macropores, which results in an efficient and dense 3D AgNW network with a small amount of AgNWs. The highly conductive and stretchable AgNW/poly­(dimethylsiloxane) (PDMS) nanocomposites are made by impregnating the 3D porous conductive network with highly stretchable poly­(dimethylsiloxane) (PDMS) matrix. The AgNW/PDMS nanocomposites exhibit a high conductivity of 42 S/cm with addition of relatively small amount of 2 wt %. The high conductivity is retained when stretched up to 120% elongation even after 100 stretching–releasing cycles. Due to high electrical conductivity and superior stretchability of AgNW/PDMS nanocomposites, these are expected to be used in stretchable electronic devices

Scalable Exfoliation Process for Highly Soluble Boron Nitride Nanoplatelets by Hydroxide-Assisted Ball Milling

The scalable preparation of two-dimensional hexagonal boron nitride (h-BN) is essential for practical applications. Despite intense research in this area, high-yield production of two-dimensional h-BN with large-size and high solubility remains a key challenge. In the present work, we propose a scalable exfoliation process for hydroxyl-functionalized BN nanoplatelets (OH-BNNPs) by a simple ball milling of BN powders in the presence of sodium hydroxide via the synergetic effect of chemical peeling and mechanical shear forces. The hydroxide-assisted ball milling process results in relatively large flakes with an average size of 1.5 μm with little damage to the in-plane structure of the OH-BNNP and high yields of 18%. The resultant OH-BNNP samples can be redispersed in various solvents and form stable dispersions that can be used for multiple purposes. The incorporation of the BNNPs into the polyethylene matrix effectively enhanced the barrier properties of the polyethylene due to increased tortuosity of the diffusion path of the gas molecules. Hydroxide-assisted ball milling process can thus provide simple and efficient approaches to scalable preparation of large-size and highly soluble BNNPs. Moreover, this exfoliation process is not only easily scalable but also applicable to other layered materials

Ordered, Scalable Heterostructure Comprising Boron Nitride and Graphene for High-Performance Flexible Supercapacitors

Heterostructures based on combining two-dimensional (2D) crystals in one stack have unusual physical properties and allow the creation of novel devices. Although this method of mechanically transferring individual 2D crystals is required for precise control, it is not scalable. Large-scale fabrication of heterostructures remains a key challenge for practical applications. Here, we provide a simple solution-based method using electrostatic interaction assembly of boron nitride (h-BN) and graphene to produce hybrid films with van der Waals heterostructures. The hybrid films prepared by this fabrication method tend to be alternately stacked and provide compact structured films. For a potential application, the h-BN/graphene hybrid films are fabricated supercapacitor’s electrodes revealing high volumetric capacitance, superior rate capability, a permanent life cycle, and high flexibility due to their synergistic effects. We anticipate that the hybrid films are useful as scalable flexible electrodes in supercapacitors, and our solution-based method has great potential for application in energy storage and electronics

Controlled Electrophoretic Deposition Strategy of Binder-Free CoFe₂O₄ Nanoparticles as an Enhanced Electrocatalyst for the Oxygen Evolution Reaction

The kinetic-sluggish oxygen evolution reaction (OER) is the main obstacle in electrocatalytic water splitting for sustainable production of hydrogen energy. Efficient water electrolysis can be ensured by lowering the overpotential of the OER by developing highly active catalysts. In this study, a controlled electrophoretic deposition strategy was used to develop a binder-free spinel oxide nanoparticle-coated Ni foam as an efficient electrocatalyst for water oxidation. Oxygen evolution was successfully promoted using the CoFe2O4 catalyst, and it was optimized by modulating the electrophoretic parameters. When optimized, CoFe2O4 nanoparticles presented more active catalytic sites, superior charge transfer, increased ion diffusion, and favorable reaction kinetics, which led to a small overpotential of 287 mV for a current density of 10 mA cm–2, with a small Tafel slope of 43 mV dec–1. Moreover, the CoFe2O4 nanoparticle electrode exhibited considerable long-term stability over 100 h without detectable activity loss. The results demonstrate promising potential for large-scale water splitting using Earth-abundant oxide materials via a simple and cheap fabrication process

Defect-Free, Size-Tunable Graphene for High-Performance Lithium Ion Battery

The scalable preparation of graphene in control of its structure would significantly improve its commercial viability. Despite intense research in this area, the size control of defect-free graphene (df-G) without any trace of oxidation or structural damage remains a key challenge. Here, we propose a new scalable route for generating df-G with a controllable size of submicron to micron through sequential insertion of potassium and pyridine at low temperature. Structural and chemical analyses confirm that the df-G perfectly preserves the intrinsic properties of graphene. The Co₃O₄ (<50 nm) wrapped by ∼10.5 μm² df-G has unprecedented capacity, rate capability, and cycling stability with capacities as high as 1050 mAh g^–1 at 500 mA g^–1 and 900 mAh g^–1 at 1000 mA g^–1 even after 200 cycles, which suggests enticing potential for the use in high performance lithium ion batteries

Engineering Nanopores in Graphene-Based Nanoplatelets Derived from Cellulose-Based Biomass for High-Performance Capacitors

While activated carbons derived from biomass resources have led to a notable enhancement in the performance of electrochemical energy storage systems, the presence of limited active sites resulting from randomly developed pores and relatively low electrical conductivity remains to be addressed. Herein we introduce a simple and cost-effective approach to generate a graphene-nanoplatelet-based structure with a large specific surface area, with prominent development of ultra-nanopores smaller than 3 nm. The electrochemical characteristics of the nanoplatelet structure were evaluated as active materials in an electrochemical double layer capacitor. To create a monolithic structure primarily composed of cellulose, we subjected balsa wood to delignification. The resulting cellulose-based monolith was subsequently subjected to carbonization and activation at various temperatures by using a chemical agent (potassium hydroxide). Structural analyses of the prepared materials revealed a high density of micro/nanopores within nanoplatelet-shaped two-dimensional particles. Especially, the Act. 900 sample (900 °C activation temperature) exhibited a large specific surface area of 1384 m2/g and a pore volume of 0.602 cm3/g with a large number of ultra-nanopores (<2 nm). Furthermore, the Act. 900-based electrode exhibited significantly enhanced capacitance (209.2 F/g), a capacitance retention of 96% at a scan rate of 300 mV/s, and cycling stability of 98% without discernible fading or decaying in capacitance after 10,000 testing cycles. This improvement in electrochemical performance can be attributed to ultra-nanopore formation in the graphene nanoplatelets and diffusion length optimization. These factors enable faster ion access and a greater number of electron pathways, thus enhancing performance. Our approach has potential applications in sustainable energy storage systems, making it feasible for practical implementation

Three-Dimensional MoS₂/MXene Heterostructure Aerogel for Chemical Gas Sensors with Superior Sensitivity and Stability

The concept of integrating diverse functional 2D materials into a heterostructure provides platforms for exploring physics that cannot be accessed in a single 2D material. Here, physically mixing two 2D materials, MXene and MoS2, followed by freeze-drying is utilized to successfully fabricate a 3D MoS2/MXene van der Waals heterostructure aerogel. The low-temperature synthetic approach effectively suppresses significant oxidation of the Ti3C2Tx MXene and results in a hierarchical and freestanding 3D heterostructure composed of high-quality MoS2 and MXene nanosheets. Functionalization of MXene with a MoS2 catalytic layer substantially improves sensitivity and long-term stability toward detection of NO2 gas, and computational studies are coupled with experimental results to elucidate that the mechanism behind enhancements in the gas-sensing properties is effective inhibition of HNO2 formation on the MXene surface, due to the presence of MoS2. Overall, this study has a great potential for expansion of applicability to other classes of two-dimensional materials as a general synthesis method, to be applied in future fields of catalysis and electronics

Enhanced Durability of Polymer Electrolyte Membrane Fuel Cells by Functionalized 2D Boron Nitride Nanoflakes

We report boron nitride nanoflakes (BNNFs), for the first time, as a nanofiller for polymer electrolyte membranes in fuel cells. Utilizing the intrinsic mechanical strength of two-dimensional (2D) BN, addition of BNNFs even at a marginal content (0.3 wt %) significantly improves mechanical stability of the most representative hydrocarbon-type (HC-type) polymer electrolyte membrane, namely sulfonated poly­(ether ether ketone) (sPEEK), during substantial water uptake through repeated wet/dry cycles. For facile processing with BNNFs that frequently suffer from poor dispersion in most organic solvents, we non-covalently functionalized BNNFs with 1-pyrenesulfonic acid (PSA). Besides good dispersion, PSA supports efficient proton transport through its sulfonic functional groups. Compared to bare sPEEK, the composite membrane containing BNNF nanofiller exhibited far improved long-term durability originating from enhanced dimensional stability and diminished chronic edge failure. This study suggests that introduction of properly functionalized 2D BNNFs is an effective strategy in making various HC-type membranes sustainable without sacrificing their original adventurous properties in polymer electrolyte membrane fuel cells