scholarly journals Nanobubble-controlled nanofluidic transport

2020 ◽  
Vol 6 (46) ◽  
pp. eabd0126
Author(s):  
Jake Rabinowitz ◽  
Elizabeth Whittier ◽  
Zheng Liu ◽  
Krishna Jayant ◽  
Joachim Frank ◽  
...  
Keyword(s):  
Ion Transport ◽  
Phase Interface ◽  
Ionic Currents ◽  
Dependent Manner ◽  
Material Transport ◽  
Transmission Electron ◽  
Three Phase ◽  
Chemical Gating ◽  
Nanofluidic Device ◽  
Inducing Surface

Nanofluidic platforms offering tunable material transport are applicable in biosensing, chemical detection, and filtration. Prior studies have achieved selective and controllable ion transport through electrical, optical, or chemical gating of complex nanostructures. Here, we mechanically control nanofluidic transport using nanobubbles. When plugging nanochannels, nanobubbles rectify and occasionally enhance ionic currents in a geometry-dependent manner. These conductance effects arise from nanobubbles inducing surface-governed ion transport through interfacial electrolyte films residing between nanobubble surfaces and nanopipette walls. The nanobubbles investigated here are mechanically generated, made metastable by surface pinning, and verified with cryogenic transmission electron microscopy. Our findings are relevant to nanofluidic device engineering, three-phase interface properties, and nanopipette-based applications.

Preparation of ordered Ag@Au hybrid nanotubes arrays and their fluorescence enhancement of poly(3-hexylthiophene)

2021 ◽  
Author(s):  
Wang Jianchao ◽  
Gege Tang ◽  
Huayong Peng
Keyword(s):  
Electron Microscope ◽  
Reaction Time ◽  
Fluorescence Enhancement ◽  
Silver Nanowires ◽  
Phase Interface ◽  
Galvanic Replacement ◽  
Replacement Reaction ◽  
Laser Raman ◽  
Transmission Electron ◽  
Three Phase

Abstract The ordered silver nanowires (Ag NWs) were assembled by three-phase interface method and the ordered Ag@Au hybrid nanotubes were successfully prepared by the galvanic replacement reaction between HAuCl4 solution and the ordered Ag NWs. Field emission scanning electron microscope (FESEM) and transmission electron microscope (TEM) were employed to analyze the morphology of the ordered Ag NWs and Ag@Au nanotubes, and the influence of reaction time in displacement reaction. Fluorescence and laser-Raman properties of conjugated polymerpoly(3-hexylthiophene) (P3HT) were analyzed on various ordered Ag@Au nanotubes on the fluorescence. The results showed that the Au particle grew on ordered Ag@Au hybrid nanotubes with the reaction time going. The fluorescence properties of P3HT films are improved on various ordered Ag@Au hybrid nanotubes compared with those on bare silicon substrate, but the fluorescence intensity of P3HT films on the ordered hybrid nanowires decreases as the galvanic displacement process.

scholarly journals Antitumor Potential of Green Synthesized ZnONPs Using Root Extract of Withania somnifera against Human Breast Cancer Cell Line

Separations ◽  
2021 ◽  
Vol 8 (1) ◽  
pp. 8
Author(s):  
Kollur Shiva Prasad ◽  
Shashanka K Prasad ◽  
Ravindra Veerapur ◽  
Ghada Lamraoui ◽  
Ashwini Prasad ◽  
...  
Keyword(s):  
Breast Cancer ◽  
Electron Microscopy ◽  
Transmission Electron Microscopy ◽  
Cell Line ◽  
Withania Somnifera ◽  
Root Extract ◽  
Dependent Manner ◽  
Sem Images ◽  
Xrd Pattern ◽  
Transmission Electron

Herein we report the synthesis of zinc oxide nanoparticles (ZnONPs) using Withania somnifera root extract (WSE) as an effective chelating agent. The microscopic techniques viz., X-ray diffraction analysis (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), high-resolution transmission electron microscopy (HRTEM), and selected area electron diffraction (SAED) were employed to analyze the as-obtained ZnONPs. The crystalline planes observed from the XRD pattern agrees with the hexagonal wurtzite structure of the as-prepared ZnONPs. The aggregations and agglomerations observed in the SEM images indicated that the size of the as-prepared ZnONPs was between 30 and 43 nm. The interplanar distance between the lattice fringes observed in the HRTEM image was found to be 0.253 nm, which is in good agreement with the (100) plane obtained in the XRD pattern. Furthermore, the anti-breast cancer cytotoxic evaluation was carried out using the MCF-7 cell line, and the results showed significant cytotoxic effects in a dose-dependent manner.

Insightful understanding of three-phase interface behaviors in 1T-2H MoS2/CFP electrode for hydrogen evolution improvement

2021 ◽  
Author(s):  
Jiamu Cao ◽  
Jing Zhou ◽  
Mingxue Li ◽  
Junyu Chen ◽  
Yufeng Zhang ◽  
...  
Keyword(s):  
Hydrogen Evolution ◽  
Phase Interface ◽  
Three Phase

Effects of histamine and histamine receptor antagonists on ion transport in rabbit descending colon

1984 ◽  
Vol 247 (4) ◽  
pp. G411-G418 ◽  
Author(s):  
R. D. McCabe ◽  
P. L. Smith
Keyword(s):  
Ion Transport ◽  
Receptor Antagonist ◽  
Prostaglandin E1 ◽  
Short Circuit ◽  
Bathing Solution ◽  
Ionophore A23187 ◽  
Dependent Manner ◽  
H2 Receptor Antagonist ◽  
Maximal Inhibition ◽  
Descending Colon

The effects of histamine on colonic ion transport were examined in in vitro preparations of rabbit descending colon. Serosal addition of histamine (10(-5) M) produced a transient increase in short-circuit current (Isc) and transepithelial conductance. The Isc response to histamine could be blocked by removing Cl from both bathing solutions, adding furosemide (10(-3) M) to the serosal bathing solution, adding indomethacin to the serosal and mucosal bathing solutions (10(-5) M), or removing Ca from the serosal bathing solution. In addition, the histamine-induced increase in Isc was inhibited in a dose-dependent manner by the H1-receptor antagonist diphenhydramine, with a maximal inhibition at 10(-4) M and a half-maximal inhibition at 3 X 10(-7) M. The H2-receptor antagonist cimetidine (10(-3) M) was without effect on the histamine response. Measurement of unidirectional Na, K, and Cl fluxes revealed that serosal addition of diphenhydramine (10(-3) M) reduced basal Isc due to a decrease in mucosal-to-serosal Na flux. Serosal addition of diphenhydramine (10(-3) M) also inhibited the increase in Isc produced by serosal addition of prostaglandin E1, 8-bromo-cAMP, cholera toxin, or the ionophore A23187. Measurement of unidirectional K and Cl fluxes revealed that prostaglandin E1 alone increased serosal-to-mucosal K and Cl fluxes and reduced the mucosal-to-serosal K flux, thereby increasing net K and Cl secretion. Serosal diphenhydramine (10(-3) M) abolished the changes in Cl fluxes produced by prostaglandin E1 and reduced the magnitude of the changes in K fluxes.(ABSTRACT TRUNCATED AT 250 WORDS)

scholarly journals Kinetic analysis of the action of Leiurus scorpion alpha-toxin on ionic currents in myelinated nerve.

1985 ◽  
Vol 86 (5) ◽  
pp. 739-762 ◽  
Author(s):  
G K Wang ◽  
G Strichartz
Keyword(s):  
Steady State ◽  
Ionic Currents ◽  
Na Channel ◽  
Dependent Manner ◽  
Na Current ◽  
Toxin Concentration ◽  
Toxin Molecule ◽  
Channel Inactivation ◽  
Na Currents ◽  
Voltage Dependent

The effects of a neurotoxin, purified from the venom of the scorpion Leiurus quinquestriatus, on the ionic currents of toad single myelinated fibers were studied under voltage-clamp conditions. Unlike previous investigations using crude scorpion venom, purified Leiurus toxin II alpha at high concentrations (200-400 nM) did not affect the K currents, nor did it reduce the peak Na current in the early stages of treatment. The activation of the Na channel was unaffected by the toxin, the activation time course remained unchanged, and the peak Na current vs. voltage relationship was not altered. In contrast, Na channel inactivation was considerably slowed and became incomplete. As a result, a steady state Na current was maintained during prolonged depolarizations of several seconds. These steady state Na currents had a different voltage dependence from peak Na currents and appeared to result from the opening of previously inactivated Na channels. The opening kinetics of the steady state current were exponential and had rates approximately 100-fold slower than the normal activation processes described for transitions from the resting state to the open state. In addition, the dependence of the peak Na current on the potential of preceding conditioning pulses was also dramatically altered by toxin treatment; this parameter reached a minimal value near a membrane potential of -50 mV and then increased continuously to a "plateau" value at potentials greater than +50 mV. The amplitude of this plateau was dependent on toxin concentration, reaching a maximum value equal to approximately 50% of the peak current; voltage-dependent reversal of the toxin's action limits the amplitude of the plateauing effect. The measured plateau effect was half-maximum at a toxin concentration of 12 nM, a value quite similar to the concentration producing half of the maximum slowing of Na channel inactivation. The results of Hill plots for these actions suggest that one toxin molecule binds to one Na channel. Thus, the binding of a single toxin molecule probably both produces the steady state currents and slows the Na channel inactivation. We propose that Leiurus toxin inhibits the conversion of the open state to inactivated states in a voltage-dependent manner, and thereby permits a fraction of the total Na permeability to remain at membrane potentials where inactivation is normally complete.

scholarly journals Modulation of cardiac Na+,K+-ATPase cell surface abundance by simulated ischemia-reperfusion and ouabain preconditioning

2013 ◽  
Vol 304 (1) ◽  
pp. H94-H103 ◽  
Author(s):  
Aude Belliard ◽  
Yoann Sottejeau ◽  
Qiming Duan ◽  
Jessa L. Karabin ◽  
Sandrine V. Pierre
Keyword(s):  
Cell Surface ◽  
Atpase Activity ◽  
Ion Transport ◽  
Cell Viability ◽  
Ischemia Reperfusion ◽  
Resistant Mutant ◽  
Surface Expression ◽  
Live Cells ◽  
Mutant Form ◽  
Dependent Manner

Na+,K+-ATPase and cell survival were investigated in a cellular model of ischemia-reperfusion (I/R)-induced injury and protection by ouabain-induced preconditioning (OPC). Rat neonatal cardiac myocytes were subjected to 30 min of substrate and coverslip-induced ischemia followed by 30 min of simulated reperfusion. This significantly compromised cell viability as documented by lactate dehydrogenase release and Annexin V/propidium iodide staining. Total Na+,K+-ATPase α1- and α3-polypeptide expression remained unchanged, but cell surface biotinylation and immunostaining studies revealed that α1-cell surface abundance was significantly decreased. Na+,K+-ATPase-activity in crude homogenates and 86Rb+ transport in live cells were both significantly decreased by about 30% after I/R. OPC, induced by a 4-min exposure to 10 μM ouabain that ended 8 min before the beginning of ischemia, increased cell viability in a PKCε-dependent manner. This was comparable with the protective effect of OPC previously reported in intact heart preparations. OPC prevented I/R-induced decrease of Na+,K+-ATPase activity and surface expression. This model also revealed that Na+,K+-ATPase-mediated 86Rb+ uptake was not restored to control levels in the OPC group, suggesting that the increased viability was not conferred by an increased Na+,K+-ATPase-mediated ion transport capacity at the cell membrane. Consistent with this observation, transient expression of an internalization-resistant mutant form of Na+,K+-ATPase α1 known to have increased surface abundance without increased ion transport activity successfully reduced I/R-induced cell death. These results suggest that maintenance of Na+,K+-ATPase cell surface abundance is critical to myocyte survival after an ischemic attack and plays a role in OPC-induced protection. They further suggest that the protection conferred by increased surface expression of Na+,K+-ATPase may be independent of ion transport.

scholarly journals Synthesis, Characterization, and Optimization of Green Silver Nanoparticles Using Neopestalotiopsis clavispora and Evaluation of Its Antibacterial, Antibiofilm, and Genotoxic Effects

2021 ◽  
Vol 5 (3) ◽  
pp. 109-122
Author(s):  
Tuğba Kahraman ◽  
Safiye Elif Korcan ◽  
Recep Liman ◽  
İbrahim Hakkı Ciğerci ◽  
Yaser Acikbas ◽  
...  
Keyword(s):  
Silver Nanoparticles ◽  
Nuclear Ribosomal Dna ◽  
Diffusion Method ◽  
Dependent Manner ◽  
Transmission Electron ◽  
Infrared Spectrophotometer ◽  
Average Size ◽  
Novel Applications ◽  
Dose Dependent

Abstract Silver nanoparticles (AgNPs) have been used in a variety of biomedical applications in the last two decades, including antimicrobial, anti-inflammatory, and anticancer treatments. The present study highlights the extracellular synthesis of silver nanoparticles AgNPs using Neopestalotiopsis clavispora MH244410.1 and its antibacterial, antibiofilm, and genotoxic properties. Locally isolated N. clavispora MH244410.1 was identified by Internal transcribed spacer (ITS) sequences of nuclear ribosomal DNA. Optimization of synthesized AgNPs was performed by using various parameters (pH (2, 4, 7, 9 and 12), temperature (25, 35 and 45 °C), and substrate concentration (0.05, 0.1, 0.15, 0.2 and 0.25 mM)). After 72 hours of incubation in dark conditions, the best condition for the biosynthesis of AgNPs was determined as 0.25 mM metal concentration at pH 12 and 35 °C. Fungal synthesized AgNPs were characterized via spectroscopic and microscopic techniques such as Fouirer Transform Infrared Spectrophotometer (FTIR), UV-Visible Spectroscopy, and Transmission Electron Microscopy (TEM). The average size of the AgNPs was determined less than 60 nm using the TEM and Zetasizer measurement system (measured in purity water suspension). The characteristic peak of AgNPs was observed at ~414 nm from UV-Vis results. Antibacterial and genotoxic activity of synthesized AgNPs (0.1, 1, and 10 ppm) were also determined by using the agar well diffusion method and in vivo Somatic Mutation and Recombination Test (SMART) in Drosophila melanogaster. AgNPs exhibited potential antimicrobial activity against all the tested bacteria (Bacillus subtilis, Staphylococcus aureus, and Pseudomonas aeruginosa) except Escherichia coli in a dose-dependent manner. AgNPs did not induce genotoxicity in the Drosophila SMART assay. 79.33, 65.47, and 41.95% inhibition of biofilms formed by P. aeruginosa were observed at 10, 1, and 0.1 ppm of AgNPs, respectively. The overall results indicate that N. clavispora MH244410.1 is a good candidate for novel applications in biomedical research.

scholarly journals Arachidonic acid promotes the binding of 5-lipoxygenase on nanodiscs containing 5-lipoxygenase activating protein in the absence of calcium-ions

2020 ◽  
Author(s):  
Ramakrishnan B. Kumar ◽  
Pasi Purhonen ◽  
Hans Hebert ◽  
Caroline Jegerschöld
Keyword(s):  
Arachidonic Acid ◽  
Complex Formation ◽  
Calcium Ions ◽  
Dependent Manner ◽  
Present Communication ◽  
Nuclear Membranes ◽  
His Tag ◽  
C Terminus ◽  
Transmission Electron

AbstractAmong the first steps in inflammation is the conversion of arachidonic acid (AA) stored in the cell membranes into leukotrienes. This occurs mainly in leukocytes and depends on the interaction of two proteins: 5-lipoxygenase (5LO), stored away from the nuclear membranes until use and 5-lipoxygenase activating protein (FLAP), a transmembrane, homotrimeric protein, constitutively present in nuclear membrane. We could earlier visualize the binding of 5LO to nanodiscs in the presence of Ca2+-ions by the use of transmission electron microscopy (TEM) on samples negatively stained by sodium phosphotungstate. In the absence of Ca2+-ions 5LO did not bind to the membrane. In the present communication, FLAP reconstituted in the nanodiscs which could be purified if the His-tag was located on the FLAP C-terminus but not the N-terminus. Our aim was to find out if 1) 5LO would bind in a Ca2+-dependent manner also when FLAP is present? 2) Would the substrate (AA) have effects on 5LO binding to FLAP-nanodiscs? TEM was used to assess the complex formation between 5LO and FLAP-nanodiscs along with, sucrose gradient purification, gel-electrophoresis and mass spectroscopy. It was found that presence of AA by itself induces complex formation in the absence of added calcium. This finding corroborates that AA is necessary for the complex formation and that a Ca2+-flush is mainly needed for the recruitment of 5LO to the membrane. Our results also showed that the addition of Ca2+-ions promoted binding of 5LO on the FLAP-nanodiscs as was also the case for nanodiscs without FLAP incorporated. In the absence of added substances no 5LO-FLAP complex was formed. Another finding is that the formation of a 5LO-FLAP complex appears to induce fragmentation of 5LO in vitro.

Wetting Behavior at Micro-/Nanoscales: Direct Imaging of a Microscopic Water/Air/Solid Three-Phase Interface

Small ◽  
2009 ◽  
Vol 5 (8) ◽  
pp. 908-912 ◽  
Author(s):  
Peipei Chen ◽  
Long Chen ◽  
Dong Han ◽  
Jin Zhai ◽  
Yongmei Zheng ◽  
...  
Keyword(s):  
Phase Interface ◽  
Direct Imaging ◽  
Wetting Behavior ◽  
Three Phase
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