Conceptual study on extraction of formic acid from the electrolyte after electroreduction of CO2: Desalination and dehydration using a high-silica chabazite zeolite membrane.

Here, we propose a two-step pervaporation system with a high-silica CHA (chabazite) membrane, which has sufficient resistance to water and acid, to demonstrate the extraction and condensation of the formic acid formed by electroreduction of CO2. The kinetic diameters of water and formic acid are similar and smaller than the pore size of CHA, while the hydrated electrolyte ions (e.g., K+ and Cl-) are larger than the pore size of CHA. Consequently, the electrolyte ions are separated from the mixture of water and formic acid in the first desalination process, and then water molecules are easily removed from the mixture in the second dehydration process. From 300 ml of an approximately 3 wt% formic acid aqueous solution containing 0.5 M KCl, 10 ml of 18.2 wt% formic acid was obtained.

Permeation behavior of porphyrin derivatives with different functional group positions across cancer cell membranes.

Porphyrin, which shows selective accumulation in cancer cells, has attracted attention as a drug carrier. The influences of the functional porphyrin positions (ß- and meso-positions) on porphyrin accumulation must be understood. In this work, we focused on the investigation of the phenyl functional group whose ß-position influences cancer cell accumulation through direct membrane permeation and endocytosis. The endocytic pathway, in particular, is influenced by both clathrin-dependent and caveolae-dependent endocytosis.

Enhanced degradation of ibuprofen using a combined treatment of plasma and Fenton reactions.

Advanced oxidation technologies (AOTs) proved to be effective in the degradation of hazardous organic impurities like acids, dyes, antibiotics etc. in the last few decades. AOTs are mainly based on the generation of reactive chemical species (RCS) such as hydroxyl, superoxide radicals etc., which plays an important role in the degradation of organiccompounds. In this work, plasma supported AOT i.e. Fenton reactions have been applied for the degradation of ibuprofen. As compared to traditional AOTs plasma assisted AOT is technologically superior due to its capability to produce RCS at a controlled rate without using chemical agents. This process work at normal room temperature and pressure. Herein, we optimized better operating conditions to generate good plasma discharge and hydroxyl radicals based on critical parameters, including frequency, pulse width and different gases like O2, Ar etc. Also, the one-pot carbonization method is used for the synthesis of Fe-based ordered mesoporous carbon (OMC) as a heterogeneous catalyst for the Fenton reactions. Using plasma-supported Fenton reactions, 88.3 % degradation efficiency is achieved using Fe-OMC catalyst for the ibuprofen degradation. Also, the mineralization of the ibuprofen is studied using total organic carbon (TOC) analysis.

Cancer cell growth suppressibility of ω-3 fatty acid whose carboxy group converted to ester group.

Recently, ω-3 fatty acids have been revealed to having cancer cell growth suppressibility. It is necessary to analyze the mechanism of cancer cell growth suppressibility and to impart selective cancer cell accumulation when creating anticancer drugs based on ω-3 fatty acids. Therefore, it is necessarily essential to introduce a luminescent molecule or a molecule which have a drug delivery function into ω-3 fatty acids, and the position of introduction is the ω-3 fatty acids' carboxyl group. On the other hand, whether the ω-3 fatty acids' cancer cell growth suppressibility is maintained when the ω-3 fatty acids' carboxyl groups are converted to other structures, such as ester groups, is unclear. In this work, a derivative was synthesized wherein the α-linolenic acid carboxyl group, one of the ω-3 fatty acids, was converted to an ester group and evaluated the cancer cell growth suppressibility, as well as the amount of cancer cell uptake. As a result, it was suggested that the ester group derivatives presented the same functionality as α-linolenic acid, and the ω-3 fatty acid carboxyl group is a flexible functional group, which can be structurally modified in terms of functionality to cancer cells.

Evaluation of Cancer Cell Growth Suppressibility of ω-3 Fatty Acids and Their Metabolites.

According to current research, cancer cell growth is suppressed by ω-3 fatty acids, which are essential fatty acids. On the other hand, ω-3 fatty acids are metabolized to bioactivities in vivo. A systematic evaluation of the ability of ω-3 fatty acids and their metabolites to suppress cancer cell growth has not been sufficiently conducted. Our work evaluated the effect of ω-3 fatty acids (docosahexaenoic acid, eicosapentaenoic acid), trans fatty acid, and the metabolites (Resolvin E1, Maresin 1) on cancer cell growth suppressibility. Our results suggest that there may be optimal fatty acids depending on the kind of cancer cells, the presence or absence of hydroxyl group, and the double bond structure involved.

Interactions between pH, reactive species, and cells in plasma-activated water can remove algae.

Lightning strikes cause nitrogen to dissolve in water and form reactive nitrogen and oxygen species, which form natural fertilizers that can be absorbed through plant roots. Such processes during rainstorm events can be simulated by applying plasma to a solution. Plasma-activated water (PAW) has great potential as a source of various dissolved reactive chemical species. Different mixtures of species are produced using different solution compositions. Here, basil seeds were grown in PAW to prevent blooms of Chlorella vulgaris and ion chromatography and UV-vis spectroscopy were used to quantify reactive ions. NO2 -, NO3 -, and H2O2 were found to be key to the antialgal effect. Secondary reactive ions such as peroxynitrite (ONOO-, ONOOH) were also involved. The antialgal effect was strongly related to the pH around the algal cells. Acidification was predominantly caused by the generation of NO2 - and H2O2. After two weeks monitoring basil growth, the antifungal properties were preserved, few reactive oxygen species formed in the plasma zone, and only reactive nitrogen species were transformed into reactive peroxynitrite ions. The pH around the cells was determined using an iridium oxide microelectrode. The PAW antialgal mechanism depended on acidic conditions (pH 2.2, at which peroxynitrite can be generated) under which ONOOH penetrated the algal cell membranes, destroying the cells and preventing growth. This practical and sustainable PAW process allows a surprising amount of fertilizer to be generated with an antialgal effect that could be used in various eco-friendly agricultural processes under ambient conditions.

Evaluation of the Correlation between Porphyrin Accumulation in Cancer Cells and Functional Porphyrin Positions of the Phenyl Group.

Porphyrin selectively shows tumour accumulation and has attracted attention as a carrier molecule for drug delivery systems (DDS). Porphyrin has two functional sites termed the meso- and ß-positions. In previous work, meso-porphyrin derivatives with an alkyl group were found to exhibit greater accumulation in human breast cancer cells (MCF-7). To identify the correlation between porphyrin accumulation and functional porphyrin positions of other functional groups, the accumulation of porphyrin derivatives with a phenyl group was investigated. The ß-porphyrin derivative with a phenyl group showed higher accumulation in MCF-7 cells and greater affinity for albumin than the meso-porphyrin derivative. The results of density functional theory (DFT) calculations suggest that the ß-porphyrin derivative with a phenyl group had higher planarity across the total structure than the meso-porphyrin derivative. It was concluded that the greater planarity of the ß-porphyrin derivative with a phenyl group might lead to superior MCF-7 cell accumulation.

Complete decomposition of sulfamethoxazole during an advanced oxidation process in a simple water treatment system.

A simple water treatment system consisting of a deep UV light (λ = 222 nm) source, a mesoporous TiO2/boron-doped diamond (BDD) photocatalyst, and a BDD electrode was prepared and used to decompose sulfamethoxazole (SMX) in an advanced oxidation process. The mesoporous TiO2/BDD photocatalyst used with the electrochemical treatment promoted SMX decomposition, but the mesoporous TiO2/BDD photocatalyst alone had a similar ability to decompose SMX as photolysis. Fragments produced through photocatalytic treatment were decomposed during the electrochemical treatment and fragments produced during the electrochemical treatment were decomposed during the photocatalytic treatment, so performing the electrochemical and photocatalytic treatments together effectively decomposed SMX and decrease the total organic carbon concentration to a trace.

Evaluation of the correlation between porphyrin accumulation in cancer cells and functional positions for application as a drug carrier.

Porphyrin derivatives accumulate selectively in cancer cells and are can be used as carriers of drugs. Until now, the substituents that bind to porphyrins (mainly at the meso-position) have been actively investigated, but the effect of the functional porphyrin positions (ß-, meso-position) on tumor accumulation has not been investigated. Therefore, we investigated the correlation between the functional position of substituents and the accumulation of porphyrins in cancer cells using cancer cells. We found that the meso-derivative showed higher accumulation in cancer cells than the ß-derivative, and porphyrins with less bulky substituent actively accumulate in cancer cells. When evaluating the intracellular distribution of porphyrin, we found that porphyrin was internalized by endocytosis and direct membrane permeation. As factors involved in these two permeation mechanisms, we evaluated the affinity between porphyrin-protein (endocytosis) and the permeability to the phospholipid bilayer membrane (direct membrane permeation). We found that the binding position of porphyrin affects the factors involved in the transmembrane permeation mechanisms and impacts the accumulation in cancer cells.

Correlations between functional porphyrin positions and accumulation in cancer cells.

Porphyrin is accumulated in tumours due to its interaction with protein. Cancer therapy with porphyrin as a carrier molecule is attracting attention. Porphyrin displays two functional sites termed ß- and meso-positions. A correlation between the functional position on the porphyrin molecule and the ability to accumulate in cancer cells is observed in the present study. The accumulation of porphyrin derivatives was determined by measuring fluorescence intensity after incubation for 2 and 24 h. The accumulation of cancer cells depended on the position and length of functional groups. Estimated binding constants between porphyrin and bovine serum albumin suggest that the position of functional groups leads to changes in binding affinity and influences the accumulation of porphyrin derivatives in cancer cells.

Synergetic effect in water treatment with mesoporous TiO2/BDD hybrid electrode.

Boron-doped diamond (BDD) electrodes have a wide potential window and can produce ozone by water electrolysis at high voltage. Though ozone has strong oxidative power (standard oxidation potential: 2.07 V vs. NHE), it cannot decompose certain types of recalcitrant organic matter completely. We developed an advanced oxidation process (AOP), in which hydroxy radicals with stronger oxidative power (standard oxidation potential: 2.85 V vs. NHE) are formed using a combination of ozone, photocatalyst, and UV. In this study, we fabricated a mesoporous TiO2/BDD hybrid electrode and examined its potential for AOPs. A synergetic effect between electrochemical water treatment and photocatalytic water treatment was observed with the hybrid electrode that did not occur with the BDD electrode.

Boron-doped Nanodiamond as an Electrode Material for Aqueous Electric Double-layer Capacitors.

Herein, a conductive boron-doped nanodiamond (BDND) particle is prepared as an electrode material for an aqueous electric double-layer capacitor with high power and energy densities. The BDND is obtained by depositing a boron-doped diamond (BDD) on a nanodiamond particle substrate with a primary particle size of 4.7 nm via microwave plasma-assisted chemical vapor deposition, followed by heat treatment in air. The BDND comprises BDD and sp2 carbon components, and exhibits a conductivity above 10-2 S cm-1 and a specific surface area of 650 m2 g-1. Cyclic voltammetry measurements recorded in 1 M H2SO4 at a BDND electrode in a two-electrode system shows a capacitance of 15.1 F g-1 and a wide potential window (cell voltage) of 1.8 V, which is much larger than that obtained at an activated carbon electrode, i.e., 0.8 V. Furthermore, the cell voltage of the BDND electrode reaches 2.8 V when using saturated NaClO4 as electrolyte. The energy and power densities per unit weight of the BDND for charging-discharging in 1 M H2SO4 at the BDND electrode cell are 10 Wh kg-1 and 104 W kg-1, respectively, and the energy and power densities per unit volume of the BDND layer are 3-4 mWh cm-3 and 10 W cm-3, respectively. Therefore, the BDND is a promising candidate for the development of a compact aqueous EDLC device with high energy and power densities.

Synthesis of Mesoporous TiO2/Boron-Doped Diamond Photocatalyst and Its Photocatalytic Activity under Deep UV Light (λ = 222 nm) Irradiation.

There is a need for highly efficient photocatalysts, particularly for water purification. In this study, we fabricated a mesoporous TiO2 thin film on a boron-doped diamond (BDD) layer by a surfactant-assisted sol-gel method, in which self-assembled amphiphilic surfactant micelles were used as an organic template. Scanning electron microscopy revealed uniform mesopores, approximately 20 nm in diameter, that were hexagonally packed in the TiO2 thin film. Wide-angle X-ray diffraction and Raman spectroscopy clarified that the framework crystallized in the anatase phase. Current⁻voltage (I⁻V) measurements showed rectification features at the TiO2/BDD heterojunction, confirming that a p⁻n hetero-interface formed. The as-synthesized mesoporous TiO2/BDD worked well as a photocatalyst, even with a small volume of TiO2 (15 mm × 15 mm × c.a. 1.5 µm in thickness). The use of deep UV light (λ = 222 nm) as a light source was necessary to enhance photocatalytic activity, due to photo-excitation occurring in both BDD and TiO2.

Solution Plasma Process-Derived Defect-Induced Heterophase Anatase/Brookite TiO2 Nanocrystals for Enhanced Gaseous Photocatalytic Performance.

We report a simple room-temperature synthesis route for increasing the reactivity of a TiO2 photocatalyst using a solution plasma process (SPP). Hydrogen radicals generated from the SPP chamber interact with the TiO2 photocatalyst feedstock, transforming its crystalline phase and introducing oxygen vacancy defects. In this work, we examined a pure anatase TiO2 as a model feedstock because of its photocatalytic attributes and well-characterized properties. After the SPP treatment, the pure anatase crystalline phase was transformed to an anatase/brookite heterocrystalline phase with oxygen vacancies. Furthermore, the SPP treatment promoted the absorption of both UV and visible light by TiO2. As a result, TiO2 treated by the SPP for 3 h showed a high gaseous photocatalytic performance (91.1%) for acetaldehyde degradation to CO2 compared with the activity of untreated TiO2 (51%). The SPP-treated TiO2 was also more active than nitrogen-doped TiO2 driven by visible light (66%). The overall photocatalytic performance was related to the SPP treatment time. The SPP technique could be used to enhance the activity of readily available feedstocks with a short processing time. These results demonstrate the potential of this method for modifying narrow-band gap metal oxides, metal sulfides, and polymer composite-based catalyst materials. The modifications of these materials are not limited to photocatalysts and could be used in a wide range of energy and environment-based applications.

Lyoprotective Effect of Alkyl Sulfobetaines for Freeze-drying 1,2-Dipalmitoyl-sn-glycero-3-phosphocholine Liposomes.

A liposome is a molecular assembly in the form of a vesicle comprised of a phospholipid bilayer. Liposomes can be used as molecular containers in various fields such as pharmaceutical, cosmetic, and food industries. It is difficult to maintain the original structure of liposomes in an aqueous medium. Phospholipids, which are components of liposomes, are susceptible to hydrolysis, which causes disruption of the liposomal structure and dysfunction of the molecular container. In this context, freeze-drying liposomes is a preferable method to improve the shelf life of liposomes. However, when freeze-drying liposomes, a lyoprotective agent is required to preserve their original structure. In this study, we investigate whether alkyl sulfobetaines (SBn, n: number of carbons in the alkyl chain, n = 1-18) can be used as lyoprotectants for 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) liposomes. The results indicated that the length of the alkyl chain of the SBn was an important factor to prevent liposome disruption during the freeze-drying and subsequent rehydration processes. The use of SBn with an alkyl chain of intermediate length (n = 6-10) could prevent liposome disruption and remarkably reduce the gel-to-liquid crystal phase transition temperature (Tm) of the freeze-dried liposomes. This indicates that these SBn could intercalate in the dried bilayer and reduce intermolecular interaction between DPPC in the bilayer. The Tm reduction of the freeze-dried liposomes should contribute to prevention of the gel-to-liquid phase transition of the liposomes during the rehydration process, which has been known to be a main cause of liposome disruption. We expect that the results from this study will provide an insight into the influence of zwitterionic additives on freeze-dried lipid bilayers and the lyoprotective effect, which should be useful in many biochemical and biomedical fields.

Platinum Nanoparticle-embedded Porous Diamond Spherical Particles as an Active and Stable Heterogeneous Catalyst.

Platinum nanoparticle-embedded porous diamond spherical particles (PtNP@PDSPs), as an active and stable catalyst, were fabricated by spray-drying of an aqueous slurry containing nanodiamond (ND) particles, platinum nanoparticles (PtNP), and polyethylene glycol (PEG) to form ND/PtNP/PEG composite spherical particles, followed by removal of PEG and a short-time diamond growth on the surface. The average diameter of the PtNP@PDSPs can be controlled in the range of 1-5 µm according to the spray-drying conditions. The Brunauer-Emmett-Teller (BET) surface area and average pore diameter of the PtNP@PDSPs were estimated to be ca. 170-300 m2 g-1 and ca. 4-13 nm, respectively. When ND with the size of 20-30 nm was used, the size of PtNP in the PtNP@PDSP was almost unchanged at 5-6 nm even after high temperature processes and reuse test for catalytic reaction, showing stable supporting. The catalytic activity of the PtNP@PDSPs for the dehydrogenation of cyclohexane was higher than that for a Pt/C catalyst, which is attributed to the stable PtNP support by the three-dimensional packing of ND and efficient mass transfer via the interconnected through-hole pores in the PDSPs.

Real-time monitoring of superoxide anion radical generation in response to wounding: electrochemical study.

BACKGROUND: The growth and development of plants is deleteriously affected by various biotic and abiotic stress factors. Wounding in plants is caused by exposure to environmental stress, mechanical stress, and via herbivory. Typically, oxidative burst in response to wounding is associated with the formation of reactive oxygen species, such as the superoxide anion radical (O2•-), hydrogen peroxide (H2O2) and singlet oxygen; however, few experimental studies have provided direct evidence of their detection in plants. Detection of O2•- formation in plant tissues have been performed using various techniques including electron paramagnetic resonance spin-trap spectroscopy, epinephrine-adrenochrome acceptor methods, staining with dyes such as tetrazolium dye and nitro blue tetrazolium (NBT); however, kinetic measurements have not been performed. In the current study, we provide evidence of O2•- generation and its kinetics in the leaves of spinach (Spinacia oleracea) subjected to wounding. METHODS: Real-time monitoring of O2•- generation was performed using catalytic amperometry. Changes in oxidation current for O2•- was monitored using polymeric iron-porphyrin-based modified carbon electrodes (φ = 1 mm) as working electrode with Ag/AgCl as the reference electrode. RESULT: The results obtained show continuous generation of O2•- for minutes after wounding, followed by a decline. The exogenous addition of superoxide dismutase, which is known to dismutate O2•- to H2O2, significantly suppressed the oxidation current. CONCLUSION: Catalytic amperometric measurements were performed using polymeric iron-porphyrin based modified carbon electrode. We claim it to be a useful tool and a direct method for real-time monitoring and precise detection of O2•- in biological samples, with the potential for wide application in plant research for specific and sensitive detection of O2•-.

A Reactive Oxygen/Nitrogen Species Sensor Fabricated from an Electrode Modified with a Polymerized Iron Porphyrin and a Polymer Electrolyte Membrane.

We have developed an electrochemical reactive oxygen/nitrogen species sensor that can detect superoxide anion radicals (O2-•) and nitric oxide (NO). The reactive oxygen/nitrogen species sensor was fabricated by surface modification of an electrode with polymerized iron tetrakis(3-thienyl)porphyrin (FeT3ThP), and it can detect either O2-• or NO by switching the applied potential. Furthermore, we fabricated a sensor with improved selectivity by coating a Nafion® film onto the poly(FeT3ThP)-modified electrode. An interference current caused by NO2- was seen for the poly(FeT3ThP)-modified electrode, while the interference current was significantly reduced at the Nafion®/poly(FeT3ThP)-modified electrode, leading to improved selectivity for NO detection. The current response at the Nafion®/poly(FeT3ThP)-modified electrode exhibited good linearity in the O2-• and NO concentration ranges 1.3 - 4.1, and 0.5 - 10 µM, respectively. The Nafion®/poly(FeT3ThP)-modified and poly(FeT3ThP)-modified electrodes are highly versatile, because these electrodes can detect either O2-• or NO by switching the applied potential. Since the Nafion®/poly(FeT3ThP)-modified and poly(FeT3ThP)-modified electrodes contain no bio-derived compounds, the reactive oxygen/nitrogen species sensor should be safe even when it is used in vivo.

Comparison of Carboxybetaine with Sulfobetaine as Lipid Headgroup Involved in Intermolecular Interaction between Lipids in the Membrane.

Diacylglycerides (DAGs) constitute an important category of lipids owing to their ability to form a lipid membrane, which can be used in a wide variety of biomedical applications. DAGs often include a zwitterionic polar headgroup that can influence the properties of the lipid membrane (e.g., protein adsorption, ion binding, hydration, membrane fluidity, phase stability) and affect their applicability. To clarify the effect of the charge arrangement of zwitterionic headgroups on intermolecular interactions in the DAG bilayers, we investigated the intermolecular interaction between a naturally occurring DAG (1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC)) and synthetic DAGs (which is called "inverse charge zwitterlipids (ICZLs)") whose headgroup charges were antiparallel with respect to those of DPPC. We used 1,2-dipalmitoyl-sn-glycero-3-carboxybetaine (DPCB) and 1,2-dipalmitoyl-sn-glycero-3-sulfobetaine (DPSB) as ICZLs and compared two combinations of the lipids (DPPC-DPCB and DPPC-DPSB). We obtained surface pressure-area (π-A) isotherms to elucidate the intermolecular interaction between the lipids in the monolayer at the air/water interface. We found shrinkage of the area per molecule in both lipid combinations, indicating that mixing DPPC with ICZLs results in an attractive intermolecular force. As an overall trend, the degree of shrinkage of the mixed monolayer and the thermodynamic favorability of mixing were greater in the DPPC-DPCB combination than in the DPPC-DPSB combination. These trends were also observed in the lipid bilayers, as determined from the gel-to-liquid crystal phase transition temperature (T c) of the aqueous dispersion of the lipid vesicles. In the highly compressed lipid monolayers and vesicles (lipid bilayer), the molar fractions of ICZLs, in which the intermolecular interaction reached a maximum, were 0.6-0.8 for the DPPC-DPCB combination and 0.5 (equimolar composition) for the DPPC-DPSB combination. Therefore, in the compressed monolayers and bilayers, the mechanism of intermolecular interaction between DPPC and DPCB is different from that between DPPC and DPSB.