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A sensitive immunosensor is developed using membrane pores as the recognition site. A Cu-free click reaction is used to efficiently immobilize antibodies, and the sensor demonstrates rapid interleukin-6 detection in the picogram per milliliter range.

The ease of anchoring single atoms on the g-C3N4 matrix, through its abundant nitrogen sites, facilitates a variety of single atom catalysts for applications in multiple domains of catalysis.

Non platinum based metal phosphide cathode electrodes with a very low Ru loading for sustainable hydrogen generation and futuristic carbon free alkaline water electrolyzers.

Proton conducting materials play an essential role in various fields of science and many applications, such as polymer electrolyte fuel cells (PEFCs). However, their proton conductivities suffer from the strong dependence on relative humidity (RH) and severely decrease at low RH conditions. Here, we synthesized zirconium (IV)-hydroxy ethylidene diphosphonates (ZrHEDP), which have phosphonic acid groups at a close distance. As the acidic groups are more concentrated in ZrHEDP, the proton conductivity exhibits lower dependence on the RH. In particular, the ZrHEDP with the largest amount of phosphonic acid groups among the examined samples showed the lowest RH dependence; the proton conductivity at 40% RH remained 2/3 of the conductivity at 95% RH, whereas a representative electrolyte, Nafion, at 40 % RH showed 1/5-1/20 of its conductivity at 95% RH.

To enhance the oxygen evolution reaction mass activity of cobalt-manganese layered oxide (CMO), we develop a one-pot synthetic process to anchor CMO onto graphene sheets (CMO/G). Its mass activity is 66-fold higher than that of physically mixed bare CMO with graphene and even better than those of previously reported graphene-supported first-row transition metal oxide-based electrocatalysts. The remarkable mass activity is attributed to the excellent intrinsic activity of CMO, small and well-dispersed CMO nanosheets on graphene sheets and hydrophilized graphene due to the synthetic process. Furthermore, CMO/G exhibits excellent stability.

Rapid, simple, and sensitive point-of-care testing (POCT) has attracted attention in recent years due to its excellent potential for early disease diagnosis and health monitoring. The flow-through biosensor design is a candidate for POCT that utilizes the small-sized pores of a porous membrane as a recognition space where it emits a signal comparable to that of a conventional enzyme-linked immunosorbent assay within 35 min of detection time. In this paper, we present a numerical model for this immunosensing technology to systematically design an improved recognition system. The model considers mass transfer into the pore (convection and diffusion), the kinetics between the immobilized receptor and the target molecule, and the flow conditions, successfully leading to a bottleneck step (capture of secondary antibody) in sandwich-type detection. Our simulation results also show that this problem can be solved by adopting both appropriate receptors and analytical conditions. Eventually, the requirements to achieve the sensitivity required for POCT were fulfilled, which will allow for further development of immunosensing devices for disease detection.

Electrochemical water splitting demands highly active, easily produced, and cost-effective electrocatalysts for the oxygen evolution reaction (OER). Herein, we present an iron (Fe)/calcium (Ca)-bas...

In the electrocatalytic CO2 reduction reaction (CO2RR), tin-based catalysts are known for their high formate faradaic yield. However higher overpotentials are required to attain a high faradaic yield with high partial current density for formate. Here, we describe the increase in the electrocatalytic CO2RR activity of Sn nanoparticles decorated on nitrogen-doped carbon fibers (NCFs) by adding a small amount of Pd. Nitrogen-doped carbon fibers decorated with SnPd nanoparticles (Sn100−yPdy–NCF) of different Sn : Pd ratios were synthesized using the electrospinning method and their electrocatalytic CO2RR activity was studied. The Sn100−yPdy–NCF catalyst with 3 wt% (y = 3) Pd displayed superior activity for the CO2RR and attained a faradaic efficiency of 85%, whereas the NCF with Sn nanoparticles (Sn100–NCF) attained only 57% efficiency at the same potential. The surface electronic configuration, Tafel slope (79 mV dec−1) and bicarbonate reduction activity of the catalyst reveal that the combination of SnOx–PdO on the catalyst surface is responsible for the superior CO2RR activity.

When human erythrocytes are subjected to high pressures for 30 min at 37 °C, hemolysis and vesiculation begin to occur at a pressure of 140 MPa. Response of the erythrocytes to 140 MPa is expected ...

Proton conducting materials suffer from low proton conductivity under low-relative humidity (RH) conditions. Previously, it was reported that acid–acid interactions, where acids interact with each other at close distances, can facilitate proton conduction without water movement and are promising for overcoming this drawback [T. Ogawa, H. Ohashi, T. Tamaki and T. Yamaguchi, Chem. Phys. Lett., 2019, 731, 136627]. However, acid groups have not been compared to find a suitable acid group and density for the interaction, which is important to experimentally synthesize the material. Here, we performed ab initio calculations to identify acid groups and acid densities as a polymer design that effectively causes acid–acid interactions. The evaluation method employed parameters based on several different optimized coordination interactions of acids and water molecules. The results show that the order of the abilities of polymer electrolytes to readily induce acid–acid interactions is hydrocarbon-based phosphonated polymers > phosphonated aromatic hydrocarbon polymers > perfluorosulfonic acid polymers ≈ perfluorophosphonic acid polymers > sulfonated aromatic hydrocarbon polymers. The acid–acid interaction becomes stronger as the distance between acids decreases. The preferable distance between phosphonate moieties is within 13 A.

New, high molecular weight poly-(fluorene-alt-tetrafluorophenylene) anion exchange membranes were synthesized by a Pd-catalyzed C–H activation method. The synthesized membranes exhibited high OH− conductivity over 100 mS cm−1, and membrane swelling could be suppressed by controlling the side chain length of the polymers. The membranes were flexible with high tensile strengh (25–42 MPa), which is comparable to Nafion 211 and likely because of their high molecular weight (Mw = 170–240 kDa). Conductivity and mechanical flexibility of the membranes did not vary significantly in 8 M NaOH at 80 °C for 168 h. These membranes hold promise for both membrane and solid ionomer materials that can be used in alkaline fuel cells or alkaline water electrolysis devices.

We propose connected Ir nanoparticle catalysts (Ir/SiO2) by coating 1.8 nm Ir particles with high density onto silica for the oxygen evolution reaction. Nanoparticles form electron-conducting networks, which can eliminate the need for an electron-conducting support. Ir/SiO2 showed a high electrochemical surface area, mass activity, and water electrolysis performance.

A heteroatom doped porous carbon electrocatalyst with enhanced oxygen reduction reaction (ORR) performance in alkaline medium was obtained by high temperature treatment of Ni incorporated ZIF-8 frameworks and its composite with g-C3N4 as a supporting matrix template. The morphology and porosity of this heteroatom containing carbon were tuned by varying the Ni : Zn molar ratio in Ni/Zn ZIF-8 and Ni/Zn ZIF-8@g-C3N4 composites. The template aided synthetic strategy using g-C3N4 helped in the controlled decomposition of composites leading to a heteroporous sheet like architecture with increased nitrogen content. The Ni/Zn ZIF-8 sample on heat treatment in the 800–1000 °C temperature range led to the formation of Ni,N co-doped porous carbon (Ni-NPC) with Ni–C active sites. The defective sites induced by nickel carbide along with the distributed N atoms on the carbon surface enabled active O2 adsorption sites. The high surface area, high degree of graphitisation as well as the defects created by well dispersed N and Ni on porous carbon matrices favoured charge separation leading to higher electrochemical ORR activity. The Ni,N co-doped carbon catalyst in alkaline medium exhibited a limiting current density of 5.2 mA cm−2 with a half-wave potential of 0.76 V vs. RHE in 0.1 M KOH. The catalyst also showed improved methanol tolerance and better stability compared to the standard Pt/C catalyst.

Highly efficient and durable catalysts are increasingly sought in water electrolysis, particularly for resolving the sluggish oxygen evolution reaction (OER) kinetics. Herein, ternary phosphides in...

Molecular recognition-induced autonomous dynamic motions, which feature in living systems, have been attracting much interest because such biological functions can promote the consequent developmen...

Long-term chemical stability of proton exchange membranes in polymer electrolyte fuel cells (PEFCs) is an important issue for widespread commercialization. Here, we report on the chemical stability of a membrane-electrode assembly with a 7 μm thick pore-filling membrane (porous substrate filled with high ion exchange capacity perfluorosulfonic acid (PFSA) polymer) using an open-circuit voltage hold test. The very thin pore-filling membrane shows comparable chemical durability to Nafion 211. Interestingly, the pore-filling membrane shows a different degradation behavior from Nafion 211 due to the use of chemically and mechanically stable porous substrate, with no thickness change and little amounts of fluorine leakages are observed in the pore-filling membrane compared to membrane thinning and large amounts of fluorine leakage in Nafion 211. The thin pore-filling membrane shows promise for application in PEFCs, as it balances high fuel cell performance at high temperature and low relative humidity with high chemical durability.

This Letter describes a new rapid and sensitive immunosensing device using the pore space of a porous membrane as the reaction space. A track-etched membrane with uniform cylindrical pores is used as the base substrate of this device. The capture antibodies are covalently and densely immobilized inside the membrane pores by the uniform introduction of poly(acrylic acid) (PAAc) via the plasma graft polymerization technique, followed by the active ester method. This membrane shows excellent antibody retention by covalent binding. The detection test was carried out via a sandwich-type assay, and all reaction steps from the antigen-antibody reaction to the enzyme reaction were conducted by permeating each solution into the pores. The detection test showed a signal comparable to that of the conventional enzyme-linked immunosorbent assay, although the detection time required in the test was shortened to 35 min. The reason for achieving both high sensitivity and short detection time is that the antibody accumulated pore space with high selectivity and promoted contact between the reactants by solution permeation. This report is expected to aid the design of systems for membrane-based devices, which currently have problems associated with sensitivity, rapidity, selectivity, or amount of sample. We further expect that this system could be applied to various diagnostic areas, including point-of-care testing.

Present energy issues have increasingly stimulated the demand for the development of clean and sustainable energy platforms which can achieve net zero carbon emissions. Renewable energy resources are quite promising candidates for the construction of sustainable decarbonized society. One of examples of harnessing renewable energy-derived electricity is the electrolysis of earth-abundant water into hydrogen, which is a prominent carbon-free chemical fuel with a high weight energy density. Compared with polymer electrolyte water electrolysis in acidic environment, electrochemical alkaline water splitting can employ inexpensive nonprecious metals as electrocatalysts, which can make this technology a large-scale and cost-effective process. However, the anodic oxygen evolution reaction (OER) in the water splitting has a large overpotential, and it is a great bottleneck for widespread use. Thus, highly active and inexpensive electrocatalysts for OER are desired to overcome this concern. Iron (Fe) is a very earth-abundant element that is a quite cheap and non-toxic metal, and thus it is a potential candidate as electrocatalyst for OER. Previous studies have reported several multimetal oxides with Fe and other metallic elements, such as perovskite and brownmillerite types, which have attracted great attentions due to their facile synthesis and easily tunable OER activities by element substitution and doping. However, most of these studies focused on the choice of elements. Contrarily, the effects of crystal structures on OER activity have not yet been sufficiently interpreted, and it can be a crucial aspect to understand the OER electrocatalysis on Fe-based oxides and for the rational design of outstanding OER catalysts. In this study, we aim to comprehensively understand the effects of crystal structures on electrocatalytic OER activities on Fe-based oxides. To obtain versatile insights into OER electrocatalysis, we collected OER performances of Fe-based simple and bimetal oxides from our experiments and literature, and their structural characteristics were obtained from databases for inorganic compounds. Thus, we found that OER efficiencies on the Fe-based oxides were correlated with Fe–O bond lengths in their crystals; i.e., a shorter Fe–O bond length led to a higher OER activity.[1] We then exploited databases to mine potential candidates based on the structure–activity relationship and selected unreported Fe-based bimetal and trimetal oxides with various structures, which can dramatically accelerate our catalyst research. We synthesized these Fe-based multimetal oxides and evaluated their OER activity in alkaline media; remarkably, the OER efficiency on the unreported Fe-based multimetal oxides also exhibited excellent correlation with Fe–O bond lengths, as plotted in Figure 1. It is notable that the trend in the Fe–O bond length and OER activity is applicable to a wide variety of Fe-based simple, bimetal, and trimetal oxides regardless of chemical compositions, crystal categories, and Fe valence states. Furthermore, machine learning analysis proved that Fe–O bond length is the most dominant structural descriptor for OER efficiency compared with other structural parameters.[2] However, it is required to overcome the abovementioned catalytic trend because theoretical Fe–O bond length in Fe-based oxides is limited, and superior OER catalysts cannot be achieved according to this design guideline. Hence, we attempted to switch the OER electrocatalytic mechanism on a Fe-based oxide by the arrangement of crystal structure because different mechanisms should be involved in different descriptors; i.e., the mechanism switch could surpass the abovementioned catalytic trend. Thus, we found post-spinel CaFe2O4 that comprises a large amount of edge-shared FeO6 connectivity in its crystal. DFT calculations unveiled that the structural characteristics induced an unprecedented OER mechanism, multi-iron-site mechanism, where OER process goes through a reaction intermediate with an O–O bridge on multiple Fe sites as depicted in upper side in Figure 1. Consequently, CaFe2O4 exhibited prominent OER activity despite long Fe–O bond length in its crystal.[3] These findings provide a novel insight into the OER electrocatalysis on Fe-based oxides and contribute to the innovation of electrochemical hydrogen production. The part of this paper is based on results obtained from a project, JPNP14021, commissioned by the New Energy and Industrial Technology Development Organization (NEDO). Authors acknowledge the PRESTO program (No. JPMJPR15S3) of the JST. The part of DFT calculations was carried out on the supercomputers at NIMS, Hokkaido Univ., Kyushu Univ., and the HPCI systems (project codes: hp180115, hp200131). The part of this work was supported by JSPS KAKENHI Grant Number 20H00314 and 20K15087. References [1] Y. Sugawara, K. Kamata, E. Hayashi, M. Itoh, Y. Hamasaki, T. Yamaguchi ChemElectroChem, 2021, 8, 4466. [2] Y. Sugawara. S. Ueno, K. Kamata, T. Yamaguchi, ChemElectroChem, 2022, 9, in press. [3] Y. Sugawara, K. Kamata, A. Ishikawa, Y. Tateyama, T Yamaguchi, ACS Appl. Energy Mater., 2021, 4, 3057. Figure 1

Cholesterol suppresses the hemolysis and the detachment of cytoskeletal proteins from bilayer in the human erythrocyte membrane under stress conditions. However, there is little information on how cholesterol functions. So, examining the role of a short side chain of cholesterol, we used the plant sterols such as β-sitosterol and stigmasterol. Incorporation of sterols into the membrane using a sterol/methyl-β-cyclodextrin complex was confirmed by the mass spectrometry. Hemolysis of human erythrocytes under high hydrostatic pressure (200 MPa) or hypotonic conditions was suppressed by cholesterol, but not by β-sitosterol and stigmasterol. Moreover, the bilayer-cytoskeleton interaction was also strengthened by cholesterol, but not by β-sitosterol and stigmasterol. Taken together, we suggest that the short side chain of cholesterol plays an important role in the membrane stability of human erythrocytes.

Background: Hereditary angioedema (HAE) is a rare but life-threatening condition. HAE types I and II (HAE-1/2) result from C1-inhibitor (C1–INH) deficiency. However, recent genetic analysis has established a new type of HAE with normal C1–INH (HAEnC1-INH). The mutations of factor XII, plasminogen, angiopoietin 1, and kininogen 1 genes may be the cause of HAEnC1-INH. Nevertheless, other causative molecules (HAE-unknown) may be involved. The Japanese therapeutic environment for HAE has been improving owing to the self-subcutaneous injection of icatibant, which was approved for the treatment of acute attack and enables early therapy. Erythema marginatum (EM) is a visible prodromal symptom which occasionally occurs prior to an angioedema attack; hence, recognizing the risk of an acute attack is important for early treatment. However, the detailed characteristics of EM remain unclear. In this study, we first investigated the clinical manifestations of EM in Japanese patients with HAE. Methods: A 20-point survey was developed and distributed to 40 physicians to gather clinical data on EM from patients with HAE. Results: Data on 68 patients with HAE (58 patients with HAE-1/2 and 10 patients with HAE-unknown) were collected. Of the patients with HAE-1/2, 53.4% experienced EM, whereas 43.1% did not. The forearm was the most frequent area of EM (64.5%), followed by the abdomen (29.0%) and upper arm and precordium (19.3%). Of the HAE-1/2 patients with EM, 41.9% always had angioedema following EM, while 29.0% always had colocalization of EM with angioedema. Moreover, 3.2% showed a correlation between the awareness of EM and severity of an angioedema attack. In 60.9% of HAE-1/2 patients with EM, the interval between the awareness of EM and appearance of angioedema was

Ti2O3 was used as a corrosion-resistive catalyst support for electrocatalytic reactions at high potential conditions. The model electrocatalyst/Ti2O3 electrode, BSCF/Ti2O3, demonstrated a considerably higher durability than a carbon support at a highly oxidative potential and completely retained its OER performance after 2000 repeated potential cycles. Therefore, Ti2O3 is promising as a conductive support for electrochemical catalytic reactions at high potential conditions.

The success of pure water solid alkaline water electrolysis (SAWE) technology currently depends on the use of polymer electrolytes exhibiting high OH– conductivity and long-term operational stabili...

The oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) are the most critical reactions that limit the efficiency of fuel cells, water electrolyzers, and metal-air batteries. Therefore, a need exists to develop cost-effective and highly active alternative electrocatalysts for ORR and OER. This study investigates the influence of metal coordination fashion on electrocatalytic ORR and OER activities among three types of Co-Mn bimetallic oxides (CMOs): tunnel-type (CMO_T), layer-type (CMO_L), and spinel-type (CMO_S) structures. An electrochemical evaluation for CMOs verifies that CMO_L has the highest ORR and OER specific activities, which is relatively better than the previously reported bifunctional metal oxides. Additionally, atomic configuration analysis for the oxides suggests that the excellent ORR and OER activities of CMO_L result from the difference in Co and Mn coordination states. This paper not only presents an excellent electrocatalyst for alkaline fuel cells and water electrolyzers but also provides an important guideline for the design of oxygen electrocatalysts.

Human erythrocytes contain abundant cholesterol as membrane lipids. Cholesterol contributes to the stability and function of the membrane. Membrane stability of the erythrocyte has been mainly examined under hypotonic conditions, but not under high hydrostatic pressure. So, the effect of cholesterol on the membrane stability of human erythrocyte was examined under a pressure of 200 MPa. As with hypotonic hemolysis, the pressure-induced hemolysis was enhanced by depletion of cholesterol from the intact erythrocyte membrane, whereas suppressed by cholesterol loading to the intact one. Enhancement of such hemolysis was associated with the suppression of fragmentation, whereas the hemolysis was suppressed by the facilitation of vesiculation. Cholesterol induced the tight linkage of the lipid bilayer with cytoskeleton. Taken together, these results suggest that the erythrocyte membrane stability is affected by such tight linkage by cholesterol.

To realize the widespread uses of polymer electrolyte fuel cells (PEFCs), the improvement of the activity and durability of Pt-based electrocatalysts for oxygen reduction reaction (ORR) is essential. In our group, a carbon-free connected Pt–Fe catalyst with a porous hollow capsule structure has been developed. [1–3] This catalyst consists of a nanosized beaded network by the connection of Pt–Fe nanoparticles. The beaded metal network is electrically conductive, enabling the removal of carbon supports form a catalyst layer. The carbon-free cathode catalyst layer using a connected Pt–Fe catalyst exhibits high durability against start/stop cycles, because of the elimination of carbon corrosion problems. In addition, the ORR specific activity of a connected Pt–Fe catalyst is about 9 times higher than that of a commercial Pt nanoparticle catalyst supported on carbon black (Pt/C). Thus, a connected Pt–Fe catalyst provides a high ORR activity and excellent start/stop durability. On the other hand, the dissolution of catalyst metals during a load cycle operation is one of critical issues for Pt-based ORR catalysts. Our previous studies using Pt-alloy nanoparticle catalysts on carbon black demonstrate that chemical ordered (superlattice) structures improve load cycle durability due to the suppression of metal dissolution. [4–8] Therefore, as shown in Figure 1A, this study developed a carbon-free connected Pt–Fe catalyst with a high chemical ordering structure to achieve high durability against both start/stop and load cycle operations. In this study, we proposed a new synthesis method using the combination of a SiO2 coating and an annealing treatment (Figure 1B) to control chemically-ordered (face centered tetragonal: fct) structures in a connected Pt–Fe catalyst. The SiO2 layer coated on catalyst surfaces prevents the detachment of Pt–Fe nanoparticles and the large catalyst agglomeration and coalescence during the high-temperature annealing. Using this method, the connected Pt–Fe catalyst having a nano-sized network and a high fct degree (70–80%) was successfully prepared. This catalyst exhibited ca. ten times higher ORR specific activity, compared with that of the Pt/C. Furthermore, as shown in Fig. 1C, the connected Pt–Fe catalyst with the high fct degree (76%) showed the higher retention of the ORR specific activity after 10000 load cycles (0.6 V for 3 s and 1.0 V for 3 s in N2-saturated 0.1 M HClO4 solution at 60 °C), compared to the catalyst with the low fct degree (47%). The results of the STEM-EDX line mapping indicated that a highly ordered fct structure greatly contributes to the suppression of metal dissolution from the catalyst. This study demonstrated, for the first time, the synthesis method as shown in Figure 1B to prepare a connected Pt–Fe catalyst with a nanosized network and a high chemical ordering structure. The carbon-free connected Pt–Fe catalyst with an enhanced chemically ordered structure exhibited a high ORR activity as well as improved durability against both start/stop and load cycle operations. The results obtained in this study provide useful guidelines for the design of high-performance ORR catalysts for PEFCs. Acknowledgements This work was financially supported by Kanagawa Institute of Industrial Science and Technology (KISTEC) and Core Research for Evolutionary Science and Technology at the Japan Science and Technology Agency (JST-CREST, JPMJCR1543). References [1] T. Tamaki, H. Kuroki, T. Yamaguchi et al., Energy Environ. Sci., 8, 3545–3549 (2015). [2] H. Kuroki, T. Tamaki, and T. Yamaguchi, J. Electrochem. Soc., 163(8), F927–F932 (2016). [3] H. Kuroki, T. Tamaki, T. Yamaguchi et al., ACS Appl. Energy Mater., 1(2), 324–330 (2018). [4] B. Arumugam, T. Tamaki, T. Yamaguchi et al., RSC Adv., 4, 27510–27517 (2014). [5] T. Tamaki, T. Yamaguchi et al., J. Power Sources, 271, 346–353 (2014). [6] B. Arumugam, T. Tamaki, T. Yamaguchi, ACS Appl. Mater. Interfaces, 4, 27510–27517 (2015). [7] H. Kuroki, T. Tamaki, T. Yamaguchi et al., Ind. Eng. Chem. Res., 55, 11458–11466 (2016). [8] T. Tamaki, H. Kuroki, T. Yamaguchi et al., J. Appl. Electrochem., 48, 773–782 (2018). Figure 1