Porous Membrane Electrode Research Articles

Cell Culture Device with a Porous Membrane Electrode for in Situ Electrochemical Measurement of Glucose Uptake and Extracellular pH

Animal testing has been widely used in drug screening. However, the metabolisms of animals are different from those of humans, and thus the failure is discovered at the clinical trial stage. Therefore, reliable tissue models using human cells are needed for drug screening. Microphysiological systems (MPSs) have recently attracted attention for constructing in vivo-like microenvironments. Porous membranes have been used in cell culture devices to fabricate tissue interfaces and functional cell spheroids. Endpoint assays are general for cell evaluation in these systems. For example, labeling of biomarkers and collecting of supernatants are required to evaluate cells. Electrochemical measurements have been used in cell analysis because of their good properties including real-time and in-situ measurements.[1] Previously, we have reported a microfluidic device with a porous membrane electrode for in-situ measurement of nitric oxide released from vascular endothelial cells.[2] In this study, we fabricated an electrochemical device integrated with a porous membrane electrode for in-situ measurement of glucose uptake[3] and extracellular pH. In glucose uptake measurement, cancer cell spheroids were put on the porous membrane electrode, and glucose was measured by enzyme-free method. In extracellular pH measurement, cells were cultured on a polyaniline-modified porous membrane electrode, and the open circuit potential versus a Ag/AgCl reference electrode was monitored.[1] Y. Utagawa et al., Electrochemical Science Advances, 2, 2022, e2100089.[2] Y. Utagawa et al., Analytical Chemistry, 95, 2023, 18158-18165.[3] Y. Utagawa et al., in preparation.

Enzyme-Free In-Situ Electrochemical Measurement Using a Porous Membrane Electrode for Glucose Transport into Cell Spheroids.

Microphysiological systems have attracted attention because of their use in drug screening. However, it is challenging to measure cell functions in real time using a device. In this study, we developed a cell culture device using a porous membrane electrode for in situ electrochemical glucose measurements for cell analysis. First, a porous membrane electrode was fabricated and electrochemically evaluated for enzyme-free glucose measurement. Subsequently, the glucose uptake of MCF-7 spheroids was evaluated using living spheroids, fixed spheroids, supernatants, and glucose transporter inhibitor-treated spheroids. Conventionally, the direct optical measurement of glucose uptake requires fluorescence-labeled glucose derivatives. In addition, the glucose uptake can be evaluated by measuring the glucose concentration in the medium by optical or electrochemical measurements. However, glucose needs to be consumed in the entire cell culture medium, which needs a long culture time. In contrast, our system can measure glucose in approximately 5 min without any labels because of in situ electrochemical measurements. This system can be used for in situ measurements in in vitro cell culture systems, including organ-on-a-chip for drug screening.

Vasculature-on-a-Chip with a Porous Membrane Electrode for In Situ Electrochemical Detection of Nitric Oxide Released from Endothelial Cells.

Vasculature-on-a-chip is a microfluidic cell culture device used for modeling vascular functions by culturing endothelial cells. Porous membranes are widely used to create cell culture environments. However, in situ real-time measurements of cellular metabolites in microchannels are challenging. In this study, a novel microfluidic device with a porous membrane electrode was developed for the in situ monitoring of nitric oxide (NO) released by endothelial cells in real time. In this system, a porous Au membrane electrode was placed directly beneath the cells for in situ and real-time measurements of NO, a biomarker of endothelial cells. First, the device was electrochemically characterized to construct a calibration plot for NO. Next, NO released by human umbilical vein endothelial cells under l-arginine stimulation was successfully quantified. Furthermore, the changes in NO release with culture time (in days) using the same sample were successfully recorded by exploiting minimally invasive measurements. This is the first report on the combination of a microfluidic device and porous membrane electrode for the electrochemical analysis of endothelial cells. This device will contribute to the development of organ-on-a-chip technology for real-time in situ cell analyses.

Electrolyte migration through electrochemical membranes: Potential source of error in batch electrochemical cells

AbstractElectrochemical membranes (ECMs) and porous electrodes have gained much attention in a broad range of applications including water and wastewater treatment, energy production and storage, and carbon dioxide capture. Lab scale batch experiments (electrochemical stirred cells) are the baseline for developing ECMs and porous electrodes. We observed electrochemical dissolution of metal fasteners (alligator clips), used to hold porous conductive and non‐conductive membranes in batch electrochemical cells, despite being kept outside the electrolyte. The electrolyte migrated through the porous membranes by the action of capillary forces, forming a closed electrochemical circuit with the metal fasteners. This unexpected leaching can lead to misleading results for electrochemical experiments on porous electrodes and ECMs. In this study, we compared (1) porous membranes versus non‐porous electrodes, (2) hydrophilic versus hydrophobic membranes, and (3) conductive versus non‐conductive membranes in their ability to cause capillary wetting‐induced corrosion of metal fasteners. We proposed a simple solution for the problem: separating the metal fasteners from the porous membrane electrode with a non‐porous conductive graphite foil, which keeps the electrochemical circuit open. We have validated this solution and propose it as a standard method for experiments using porous electrodes and electrically conductive membranes.

Thiophilic-Lithiophilic Hierarchically Porous Membrane-Enabled Full Lithium-Sulfur Battery with a Low N/P Ratio.

Lithium-sulfur batteries stand out as the next-generation batteries because of their high energy density and low cost. However, the shuttle effect of lithium polysulfides (LiPSs), growth of lithium dendrites, and overuse of lithium resources still hinder their further application. To address these problems, we constructed a porous network structure in which Sn is melted and coated on a frame that has a carbon nanotube (CNT) core and a nitrogen-doped carbon (NC) coating as cross-linking shell (CNT@NC@Sn). This hierarchically porous membrane electrode, which has an ultrahigh porosity of approximately 90%, works as a matrix to strengthen the conductivity of Li+ and electrons and provides enough space for the conversion between sulfur and LiPSs. Moreover, the in situ thin coating of Sn not only promotes the adsorption and catalytic conversion of LiPSs but also provides lithiophilic binding sites and induces uniform lithium deposition. Thus, the thiophilic-lithiophilic porous membrane electrode with lithium loaded on the frame (in the form of Sn-Li alloy) by electroplating can replace lithium sheets, reduce the use of Li, and improve the safety performance of the battery. Additionally, these dual-functional membranes boost the reaction kinetics and conductivity of the cathode by dispersing the sulfur slurry in the porous membrane framework. As a result, the lithium-sulfur full battery assembled with the CNT@NC@Sn integrated membrane electrode exhibits stable cycling with a reversible capacity of 617.1 mAh g-1 after 200 cycles at 1 C. The capacity decay rate per cycle is 0.105%, and the N/P ratio is as low as 2.98.

Position difference between Mo clusters and N sites induced highly synergistic electrocatalysis in integrated electrode-separator membranes with crosslinked hierarchically porous interface

Herein, scalable integrated electrode-separator membranes with hierarchical porous interface are reported for promoting Li+/electrolyte transfer and Al-free refined Li-S battery configuration. The electrode side (CNT@Mo-NC) with ultrahigh porosity of 89% is composed with CNT as skeleton and Mo/N-codoped carbon (Mo-NC) as the crosslinked shell, the unique porous membrane electrode side and interface can strengthen transfer of Li+/electrons/electrolyte for fast reaction kinetics, and provide large space for polysulfide (LiPSs) anchoring and volume expansion. Furthermore, the N active sites with Li+-transfer transition function and Mo clusters with LiPSs adsorption and catalytic ability constitute a highly-efficient synergistic effect in mitigating shuttle effect and reducing energy barrier of redox reaction. For the Mo13NC-a surface with adjacent Mo and N, the LiPSs are adsorbed by Mo during the discharge process, and the N sites with lone electron pairs can accelerate diffusion of the positively charged Li+ to Mo, and to react quickly with LiPSs and transform into Li2S. For Mo13NC-b surface, however, the repulsion effect between Mo and Li+ during the charge process can promote the rapid migration of the dissociated Li+ to surround graphene due to the N center is occupied by Mo, which is beneficial to the dissociation reaction of Li2S. For the separator side (CNT@NP) with CNT as the skeleton and nonconductive polymer (NP) as crosslinked shell, the porous structure also facilitates the Li+/electrolyte transport. With uniform sulfur loading in the electrode side, an Al/Cu free Li-S battery with refined configuration and long-term cycle stability is formed. The proposed strategy has an important guiding significance for the design of membrane-based electrode/separator/interlayer with low ion/electrolyte transfer resistance in Li-S batteries.

Freestanding N-doped graphene membrane electrode with interconnected porous architecture for efficient capacitive deionization

Freestanding electrodes without the influences of additives have been considered as a kind of ideal electrode structure in the field of capacitive deionization (CDI). However, subjected to conductivity, available surface areas, hydrophilicity and etc., effectively construction of freestanding CDI electrodes with high water desalination performance still face great challenges. Herein, we will demonstrate a unique N-doped graphene freestanding porous membrane electrode with excellent water desalination performance. The preparation process mainly includes the assembly of core-shell composites with incomplete graphene oxide shells into bulk membranes using compression molding method and the heat-treatment under NH3 atmosphere. These reserved spherical shells with loopholes and N-doping make up the freestanding membrane electrodes with network porous architecture. The interconnected sphere shells efficiently improve the availability of surface and pores in the monolithic assembly, while the doping of nitrogen element further enhances the accessibility of graphene-based surface by the electrolyte. As a result, such graphene carbonaceous freestanding electrodes exhibit excellent water desalination performance with a high CDI capacity of about 21.8 mg/g in NaCl solution. Moreover, such freestanding membrane electrodes also possess good desalination abilities towards some other salts such as KCl, CaCl2 and MgCl2, suggesting their potential applications in complex brine solution.

Fabrication of tubular porous titanium membrane electrode and application in electrochemical membrane reactor for treatment of wastewater

In this study, tubular titanium membrane (TTM) /SnO2-Sb/SnO2-Sb-CeO2 porous anode was fabricated and used in continuous tubular membrane reactor for electrochemical treatment of dye wastewater. X-ray diffraction (XRD), scanning electron microscopy (SEM) and high-resolution transmission electron microscopy (HRTEM) were used to evaluate the morphology and microstructure of the different tubular titanium membrane. Linear sweep voltammetry (LSV) and accelerated service life test are employed to illustrate the performance of TTM/SnO2-Sb/SnO2-Sb-CeO2 porous membrane electrode. It is found that TTM/SnO2-Sb/SnO2-Sb-CeO2 active layer on titanium membrane has compact microstructure, high over-potential for oxygen evolution (2.10V vs saturated calomel electrode). The effects of pore diameter, applied voltage and flow rate on the electro-catalytic property of the tubular porous electrode were investigated. Study shows titanium membrane reactor with an optimized pore diameter of 10μm has the lowest energy consumption which is important for the practical application of electrochemical technology. The performance of titanium tubular membrane reactor is investigated by treating methylene blue (MB) wastewater under the cell voltage of 3.0–4.5V and the flow rate of 2.5–3.5Lmin−1. This continuous titanium membrane electrochemical reactor using solar cell show excellent performance in treating dye wastewater and the further potential application in electrochemical synthesis.

Engineering Interface with a One-Dimensional RuO2/TiO2 Heteronanostructure in an Electrocatalytic Membrane Electrode: Toward Highly Efficient Micropollutant Decomposition.

Decomposition of micropollutants using an electrocatalytic membrane reactor is a promising alternative to traditional advanced oxidation processes due to its high efficiency and environmental compatibility. Rational interface design of electrocatalysts in the membrane electrode is critical to the performance of the reactor. We herein developed a three-dimensional porous membrane electrode via in situ growth of one-dimensional RuO2/TiO2 heterojunction nanorods on a carbon nanofiber membrane by a facile hydrothermal and subsequent thermal treatment approach. The membrane electrode was used as the anode in a gravity-driven electrocatalytic membrane reactor, exhibiting a high degradation efficiency of over 98% toward bisphenol-A and sulfadiazine. The superior electrocatalytic performance was attributed to the 1D RuO2/TiO2 heterointerfacial structure, which provided the fast electron transfer, high generation rate of the hydroxyl radical, and large effective surface area. Our work paves a novel way for the fundamental understanding and designing of novel highly effective and low-consumptive electrocatalytic membranes for wastewater treatment.

Compact mixed-reactant fuel cells

The compact mixed-reactant (CMR) fuel cell is an important new “platform” approach to the design and operation of all types of fuel cell stacks. Amongst several other advantages, CMR has the potential to reduce polymer electrolyte membrane (PEM) stack component costs by around a third and to raise volumetric power densities by an order of magnitude. Mixed-reactant fuel cells, in which the fuel and oxidant within a cell are allowed to mix, rely upon the selectivity of anode and cathode electrocatalysts to separate the electrochemical oxidation of fuel and reduction of oxidant. A comprehensive review of the 50-year history of mixed-reactant literature has demonstrated that such systems can perform as well as and, in some circumstances, much better than conventional fuel cells. The significant innovation that Generics has introduced to this field is to combine the concept of mixed-reactant fuel cells with that of a fully porous membrane electrode assembly (MEA) structure. Passing a fuel–oxidant mixture through a stack of porous cells allows the conventional bipolar flow-field plates required in many fuel cell designs to be eliminated. In a conventional PEM stack, for example, the bipolar carbon flow-field plates may block up to half of the active cell area and account for up to 90% of the volume of the stack and of the order of one-third of the materials costs. In addition to all the advantages of mixed-reactant systems, the “flow-through” mode, embodied in Generics’ CMR approach, significantly enhances mass-transport of reactants to the electrodes and can reduce reactant pressure drops across the stack. Redesigning fuel cells to operate in a CMR mode with selective electrodes offers the attractive prospect of much reduced stack costs and significantly higher stack power densities for all types of fuel cell. Initial modeling and proof of principle experiments using an alkaline system have confirmed the validity of the CMR approach and the potential for substantial performance improvements.

Determination of total sulphur and nitrogen in crude oil products by oxidative pyrolysis with detection using a metal-plated membrane electrode

Following oxidative pyrolysis of the sample, the gaseous products are detected amperometrically at a gold-plated porous membrane electrode. In the determination of sulphur, the gaseous products are fed directly to the electrode; in the determination of nitrogen, the gaseous products are passed through a column containing PbO2, in which SO2 is removed and NO is converted into NO2. The calibration graphs are linear in the ranges 7–1500 p.p.m. (S) and 5–1000 p.p.m. (N), the sensitivity of the determination is 8.4 nA (p.p.m.)–1(S) and 4.2 nA (p.p.m.)–1(N), and the detection limits are 2.5 p.p.m. (S) and 7.8 p.p.m. (N). The analysis time is 10–15 s.

Application of a metallized membrane electrode for the determination of gaseous sulphur compounds after reductive pyrolysis

Sulphur-containing gases are converted by non-catalytic reductive pyrolysis into an equivalent amount of H 2S, which is determined by electrochemical oxidation at a gold-plated porous membrane electrode. The calibration for H 2S is linear up to 18 ml/m 3 with a slope of 1.12 μA.m 3.ml −1. The relative standard deviation for the determination of 3.7 ml/m 3 H 2S was 1.0% and the detection limit 4 μl/m. About 60 samples can be determined per hour. The method has been employed for the determination of total sulphur and individual gases after separation on a chromatographic column.

Amperometric detection of nitrates using a flow-through membrane detector

A flow-through amperometric detector has been developed based on the electrochemical reduction of nitrates at a silver cathode. The nitric oxide formed is detected by a gold-plated porous membrane electrode placed downstream in the detector. Nitrates were mostly determined in samples containing 5 × 10 −2 M H 2SO 4. The sensitivity of the determination is expressed as the slope of the regression straight line was 0.85 nA μ M −1 in the range 5 × 10 −6 to 10 −3 M NO − 3. The limit of quantitation determined as ten times the peak-to-peak background noise amplitude was 8 × 10 −7 M NO − 3. The relative standard deviation for the determination of 5 × 10 ∂ and 10 −4 M NO − 3 was 3.6 and 0.8%, respectively. The most important interference in the determination of nitrate is that from nitrite, which exhibits identical behaviour in the determination. A method has been proposed which eliminates the effect of nitrite and permits its simultaneous determination in the presence of nitrate.

Pneumatopotentiometric determination of nanogram amounts of cyanide

Hydrogen cyanide is liberated from aqueous samples by reaction with sulphuric acid and transferred by a stream of nitrogen to a silver porous membrane electrode. Some HCN passes through the membrane into an alkaline dicyanoargentate solution; the cyanide ion produced causes a decrease in the equilibrium Ag + concentration and the change of potential is related to the amount of cyanide in the sample. The detection limit is 3.0 ng ml −1 cyanide in the injected solution; the relative standard deviation is 0.82% for 17 ng of cyanide. Sulphide interferes (as H 2S) but can be removed on a lead acetate column.

Determination of subnanogram amounts of sulfur dioxide and sulfites by pneumatopotentiometry

Gold porous membrane electrode has been used for the potentiometric determination of small amounts of sulfur dioxide absorbed in the solutions of sodium tetrachloromercurate or sodium hydroxide. Sulfur dioxide is released by the reaction with an acid into a stream of nitrogen and led to the electrode immersed into the solution of iodine monochloride. Part of SO2 penetrates through the membrane pores into the solution where it is oxidized. The electrode redox potential change is a measure of the SO2 concentration in the absorption solution. In the solution of 1 . 10-5 M[ICl2]- in 0.02 M-HClO4 the limit of quantitation was found to be 0.07 ng SO2 . ml-1. The relative standard deviations of 1.4% and 2.5% were found for the determinations of 10 ng and 0.5 ng of SO2, respectively. Higher concentrations of H2S interfere only in the hydroxide solution. About 10 samples can be analyzed per one hour.

Determination of gaseous hydrogen sulfide by cathodic stripping voltammetry after preconcentration on a silver metalized porous membrane electrode

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTDetermination of gaseous hydrogen sulfide by cathodic stripping voltammetry after preconcentration on a silver metalized porous membrane electrodeFrantisek. Opekar and Stanley. BruckensteinCite this: Anal. Chem. 1984, 56, 8, 1206–1209Publication Date (Print):July 1, 1984Publication History Published online1 May 2002Published inissue 1 July 1984https://doi.org/10.1021/ac00272a004RIGHTS & PERMISSIONSArticle Views126Altmetric-Citations13LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (532 KB) Get e-Alerts Get e-Alerts