Glass Microfiber Membrane Research Articles

Target immobilization on glass microfiber membranes as a label-free strategy for hit identification.

The discovery of novel chemical entities targeting G protein-coupled receptors (GPCRs) is usually guided by their receptor affinity. However, traditional affinity assay methods and hit identification procedures are usually laborious and expensive. In this work, the type-2 vasopressin receptor (V2R) was chosen as a prototypical GPCR. Membrane fragments from cells highly expressing SNAP-V2R were immobilized on the surface of a glass microfiber (GMF) coated with O6-benzylguanine (BG). This was achieved by transferring the benzyl group of BG to the active site of the SNAP-tag through a nucleophilic substitution reaction. As a result, a biofilm called SNAP-V2R@GMF-BG was produced that showed good specificity and stability. The adsorption ratio for each V2R ligand treated with SNAP-V2R@GMF-BG was determined by HPLC and exhibited a good linear correlation with the Ki value determined by displacement assays. Furthermore, a Ki prediction assay was performed by comparing the data with that generated by a homogeneous time-resolved fluorescence (HTRF) assay. SNAP-V2R@GMF-BG was also used to screen hit compounds from natural products. After SNAP-V2R@GMF-BG was incubated with the total extract, the ligand that binds to V2R could be separated and subjected to LC‒MS analysis for identification. Baicalein was screened from Clerodendranthus spicatus and verified as a potential V2R antagonist. This V2R-immobilized GMF platform can help determine the affinity of V2R-binding hit compounds and screen the compounds efficiently and accurately.

The Double-Edged Effect of Water on Li-O2 Aprotic Batteries

Storing larger amounts of energy is becoming critical as more renewable and intermittent energy sources emerge in our society. Li-O2 batteries have the highest theoretical energy density, but there are still barriers to overcome. The presence of water in atmospheric air makes studying its effects on battery performance necessary if ambient oxygen ought to be used in such devices. This paper investigates the effect of different concentrations of water in the electrolyte of Li-O2 aprotic batteries, on deep discharge capacity and cyclability. Batteries were prepared with a metallic lithium anode, glass microfiber membrane, 0.1 M LiClO4/DMSO electrolyte with various water concentrations (15–144,000 ppm), and carbon paper cathode. An increase in discharge capacity of >300% was achieved with 550 ppm of water; however, a gradual reduction in cyclability was observed increasing water concentration. We show that it occurs due to changes in the reaction mechanism, composition, and morphology of the discharge products, incomplete decomposition, and formation of a passivating film on the metallic lithium anode. Moreover, this article elucidates the causes underlying the involved mechanism and highlights the double-edged effect of water on the electrochemical performance of Li-O2 batteries, causing improvements in deep discharge capacity at the cost of reduced cyclability.

Concepts for millimeter wave-based detection of African trypanosomes in field-compatible liquid systems

Abstract Human African Trypanosomiasis (HAT) is caused by the African trypanosome, a single-cell parasite that proliferates in the blood and cerebrospinal fluid of infected patients. Diagnostic measures for this pathogen are currently not sufficiently robust and reliable enough to permit effective disease control procedures. As a consequence, we suggested the development of a new sensor type, combining the selectivity of parasite-specific nucleic acid aptamers with the sensitivity of resonant electromagnetic devices to capture and detect the disease-causing organism. While we accomplished the detection of parasite cells in dehydrated specimens, here we summarize our recent progress toward electromagnetic sensors capable of uncovering parasites in liquid patient samples. We present a technique for the removal of blood cells from blood specimens and the deposition of trypanosome cells on glass microfiber membranes for dielectric spectrometry. Liquid suspensions of trypanosomes are characterized to determine the actual dielectric properties of single parasites and lastly, we present two sensor concepts optimized for the detection in liquids, along with a fabrication technique for the integration of microfluidic sample confinements.

Synergy of copper Selenide/MXenes composite with enhanced solar-driven water evaporation and seawater desalination

Despite significant of solar energy to power water evaporation in seawater desalination, the commercial application of this technology is limited by the poor light absorption and low photothermal conversion of existing photothermal materials. Herein, we report a simple method for solar-driven water evaporation using a device comprising Cu2-xSe/Nb2CTx nanocomposites supported by a glass microfiber membrane, which utilizes cotton thread as water transport pathway. The proposed device demonstrates excellent light absorption, water transportation, and thermal management. Benefiting from the strong synergetic photothermal effect of Cu2-xSe and Nb2CTx, the Cu2-xSe/Nb2CTx nanocomposites function as an efficient solar absorber with excellent photothermal conversion efficiency. The rough surface, low thermal conductivity and good hydrophilicity of glass microfiber membrane could maximize light capture, limit heat loss, and timely replenish water during the water evaporation process. When evaluated as a water evaporation system for outdoor seawater desalination, the system achieved a water evaporation of 12.60 kg·m−2 within 6 h. High fresh water generation rate is an important embodiment of high photothermal conversion efficiency. This study demonstrates a new route for designing solar desalination devices with high photothermal conversion properties.

Wicking microfluidic approach to separate blood plasma from whole blood to facilitate downstream assays.

Separation of blood plasma or serum from blood is essential for accurate analysis. Conventional blood separation requires instrumentation, reagents, and large sample volumes, limiting this process to laboratory environments with trained personnel. Full implementation of effective blood separation and analysis on microliter sample volumes for point of care (POC) diagnostics has proven extremely challenging resulting in a growing market demand, with common challenges such as expensive device fabrication processes or devices being comprised of materials which are not easily disposable. We developed a membrane-based wicking microfluidic device which is made using a simple fabrication process. This device uses a unique 3D flow channel geometry, fabricated in a polycaprolactone-filled glass microfiber membrane, to efficiently separate microliter sample volumes of blood. Colorimetric assay chemistries were integrated to demonstrate utility of these devices in POC diagnostics. The devices are capable of separating both fresh and anticoagulant-treated blood at microscale sample volumes (<15.0μL). Modifications to the base device are also reported herein which increased sample volume capacity and separation efficiency. Integrated colorimetric assay enabled semi-quantitative detection of conjugated bilirubin in real blood samples (1.0-1.5mg/dL). These blood separation devices, fabricated on polycaprolactone-filled glass microfiber, enabled effective blood plasma (anticoagulant-treated blood) and serum (fresh blood) separation with microscale sample volumes. Sample volume capacity and separation efficiency are customizable for specific applications and devices can be integrated with downstream assay chemistries to develop complete POC devices that offer blood separation and diagnostics at the same time on a single membrane.

Robust and continuous oil/water separation with superhydrophobic glass microfiber membrane by vertical polymerization under harsh conditions

We report a robust and continuous oil/water separation with nanostructured glass microfiber (GMF) membranes modified by oxygen plasma treatment and self-assembled monolayer coating with vertical polymerization. The modified GMF membrane had a nanostructured surface and showed excellent superhydrophobicity. With an appropriate membrane thickness, a high water intrusion pressure (< 62.7 kPa) was achieved for continuous pressure-driven separation of oil/water mixtures with high flux (< 4418 L h−1 m−2) and high oil purity (> 99%). Under simulated industrial conditions, the modified GMF membrane exhibited robust chemical stability against strong acidic/alkaline solutions and corrosive environments. The proposed superhydrophobic composite coating technique is simple, low cost, environmentally friendly, and suitable for the mass production of scalable three-dimensional surfaces. Moreover, its stability and customizable functionality offers considerable potential for a wide range of novel applications.

Hydrogel-Polymer Electrolyte for Electrochemical Capacitors with High Volumetric Energy and Life Span.

AC/AC (AC=activated carbon) electrochemical capacitors (ECs) were designed with a 1 mol L-1 lithium sulfate hydrogel- polymer electrolyte (HPE) based on carboxymethyl cellulose sodium salt (CMC). The electrochemical performance of the ECs was compared with that of cells composed of common separators such as a polyolefin membrane (Celgard 3501, polypropylene separator coated by surfactant) and a glass microfiber membrane (Whatman GF/A). The ECs with Celgard 3501 and home-made CMC-HPE demonstrated a higher volumetric energy than that with Whatman GF/A. However, after 120 h of floating at 1.5 V, the capacitance of the EC with Celgard 3501 decreased dramatically by 25 %, whereas with CMC-HPE and Whatman GF/A, the decrease was only 4 and 6 %, respectively. Post-mortem observations of the Celgard 3501 separator after floating suggested that the surfactant layer was removed, which caused a decrease of separator wettability, as confirmed by the slow evolution of the electrolyte contact angle on its surface. Hence, CMC-HPE is a very attractive option to develop aqueous-electrolyte-based ECs with an excellent life span and high volumetric energy density.

High-performance and low-leakage phosphoric acid fuel cell with synergic composite membrane stacking of micro glass microfiber and nano PTFE

A novel composite membrane consisting glass microfiber (GMF) and polytetrafluoroethylene (PTFE) nanoporous film is applied to phosphoric acid fuel cell (PAFC) for performance enhancement and reducing electrolyte leakage. With 93% high porosity, the GMF can fully load phosphoric acid to maintain high proton conductivity. However, the large opening of the GMF membrane cannot effectively prevent the leakage of phosphoric acid. Therefore, in this study, a 25 μm thick PTFE thin film with pore size 50–400 nm is employed to cover the surface of GMF for preventing phosphoric acid leakage. This composite proton exchange membrane possesses both thermal and chemical stability at the working temperature of phosphoric acid fuel cell, while providing high proton conductivity. The proton conductivity of the composite membrane (0.71 S/cm at 150 °C) is much higher than those of reported phosphoric acid porous membranes (∼10−2 S/cm at 150 °C). The fuel cell using the composite membrane with Pt/C catalyst exhibits excellent performance with peak power density of 614 mW/cm2 and current density of 1761 mA/cm2 at 140 °C under pure H2 and O2 supply, while proton conductivity is maintained 2.6 times higher than that of the pure GMF membrane due to the less phosphoric acid leakage by using PTFE film.

Robust and thermal-enhanced melamine formaldehyde–modified glassfiber composite separator for high-performance lithium batteries

The composite separator of melamine formaldehyde resin coated glass microfiber membrane was prepared for high performance lithium ion battery. It was demonstrated that this composite membranes possessed a significantly enhanced tensile strength and a modified porous structure, compared with that of pristine glass microfiber membrane. Impressive improvements in thermo-stability, with no shrinkage at an elevated temperature of 150°C. Meanwhile, such composite membrane presented a favorable wettability and remarkable electrochemical stability in commercial liquid electrolyte. In addition, the battery test results of LiCoO2/graphite cells proved the composite membrane was a promising separator with an improved cycling performance and rate capability. The cycle performance of LiFePO4/Li cells at the elevated temperature of 120°C demonstrated their excellent safety characteristic as separator in LIB, indicating the composite membrane was a potential separator candidate for high power battery.

Investigating Li Microstructure Formation on Li Anodes for Lithium Batteries by in Situ 6Li/7Li NMR and SEM

The growth of lithium microstructures during battery cycling has, to date, prohibited the use of Li metal anodes and raises serious safety concerns even in conventional lithium-ion rechargeable batteries, particularly if they are charged at high rates. The electrochemical conditions under which these Li microstructures grow have, therefore, been investigated by in situ nuclear magnetic resonance (NMR), scanning electron microscopy (SEM), and susceptibility calculations. Lithium metal symmetric bag cells containing LiPF6 in EC/DMC electrolytes were used. Distinct 7Li NMR resonances were observed due to the Li metal bulk electrodes and microstructures, the changes in peak positions and intensities being monitored in situ during Li deposition. The changes in the NMR spectra, observed as a function of separator thickness and porosity (using Celgard and Whatmann glass microfiber membranes) and different applied pressures, were correlated with changes in the type of microstructure, by using SEM. Isotopically en...

A superior thermostable and nonflammable composite membrane towards high power battery separator

The composite membrane of glass microfiber and polyimide was prepared by paper making method and following dip-coating process to explore the feasibility as high performance separator of lithium ion battery (LIB). It was demonstrated that the composite membranes, with a thickness of about 45μm, possessed a significantly enhanced tensile strength and a modified porous structure, compared with that of pristine glass microfiber membrane. Impressive improvements in thermostability and flame retarding were achieved for composite membrane, with no shrinkage at the elevated temperature of 200°C, even no burn on fire, compared with commercial polyolefin separators. Meanwhile, the composite membrane presented a favorable wettability and remarkable electrochemical stability in commercial liquid electrolyte. In addition, the battery test results of LiFePO4/Li and LiFePO4/graphite cells proved the composite membrane was a promising separator with an improved rate capability. The cycle performance of cells at the elevated temperature of 120°C demonstrated their excellent safety characteristic as separator in LIB, indicating the composite membrane was a potential separator candidate for high power battery.

Chemisorption of estrone in nylon microfiltration membranes: Adsorption mechanism and potential use for estrone removal from water

Estrone is a representative steroid estrogen contaminant that has been detected in effluents from sewage treatment facilities, as well as in surface and ground waters. Our study shows that estrone can be readily removed from water via a unique chemisorption mechanism using nylon microfiltration membranes. Experiments on a laboratory in-line filtration system showed instant removal of estrone from 200 μg/l aqueous solutions by 0.45-μm nylon membranes ( ca. 35 L per m 2 membrane). Comparisons with 0.45-μm PVDF, PTFE and glass microfiber membranes suggested that the significant estrone adsorption in nylon membrane should be predominately driven by a different mechanism rather than common physical adsorption. Fourier transform infrared spectroscopy study on nylon membranes and a model compound, N-methylacetamide, showed that the significant adsorption originated from the hydrogen bonding between terminal –OH groups on estrone molecules and nucleophile –C O groups in amide groups of nylon 6,6. The saturated nylon membrane showed very low leachability in ambient water, while it could be effectively regenerated in alkaline or ethanol solutions. Preliminary reusability study showed that the membrane maintained a consistent adsorption capacity for estrone during ten cycles of reuse. The chemisorption-based polymeric adsorption may provide a new alternative approach for removing estrone and potentially other trace organic contaminants from water.