scholarly journals Sensing Hydration of Biomimetic Cell Membranes

Biosensors ◽  
2021 ◽  
Vol 11 (7) ◽  
pp. 241
Author(s):  
Madhurima Chattopadhyay ◽  
Hanna Orlikowska ◽  
Emilia Krok ◽  
Lukasz Piatkowski
Keyword(s):  
Lipid Bilayers ◽  
Structural Integrity ◽  
Aqueous Media ◽  
Chemical Species ◽  
Model Systems ◽  
Develop Model ◽  
Complex Nature ◽  
Water Molecules ◽  
Hydration Properties ◽  
Hydration State

Biological membranes play a vital role in cell functioning, providing structural integrity, controlling signal transduction, and controlling the transport of various chemical species. Owing to the complex nature of biomembranes, the self-assembly of lipids in aqueous media has been utilized to develop model systems mimicking the lipid bilayer structure, paving the way to elucidate the mechanisms underlying various biological processes, as well as to develop a number of biomedical and technical applications. The hydration properties of lipid bilayers are crucial for their activity in various cellular processes. Of particular interest is the local membrane dehydration, which occurs in membrane fusion events, including neurotransmission, fertilization, and viral entry. The lack of universal technique to evaluate the local hydration state of the membrane components hampers understanding of the molecular-level mechanisms of these processes. Here, we present a new approach to quantify the hydration state of lipid bilayers. It takes advantage of the change in the lateral diffusion of lipids that depends on the number of water molecules hydrating them. Using fluorescence recovery after photobleaching technique, we applied this approach to planar single and multicomponent supported lipid bilayers. The method enables the determination of the hydration level of a biomimetic membrane down to a few water molecules per lipid.

The organization and function of water in protein crystals

1977 ◽  
Vol 278 (959) ◽  
pp. 3-32 ◽  
Keyword(s):  
Protein Interactions ◽  
Active Sites ◽  
Structural Integrity ◽  
Bound Water ◽  
Structural Data ◽  
Protein Molecule ◽  
Biologically Active ◽  
Complex Nature ◽  
Water Molecules ◽  
And Function

Dry proteins are dead, or at best asleep. Substitution of D 2 O can drastically alter biological activity. Water is thus essential in maintaining the structural integrity of biologically active macromolecules, and is implicated in their functioning. Such water may occupy a range of dynamical states, from being strongly bound and localized, to more labile and ‘liquid-like’. Spatially ordering the macromolecules aids the search for the more localized water molecules. For example, diffraction experiments on single crystals can resolve ‘bound’ water molecules within a protein molecule - often at active sites, coordinated to metals or ions. Less precise information is obtained on the partially occupied external water sites, which are of importance to the folding and the dynamics of the biomolecule. Orientation of fibrous molecules increases the information obtainable from n.m.r. experiments. Combination of other experimental results on disordered aggregates (e.g. in solution) with chemical and structural data on the macromolecule and water itself yields useful, if circumstantial, information. Statistical and computer techniques may help to elucidate the complex nature of water-protein interactions, and to interpret the results of more complex experiments.

scholarly journals Lipid Transporters Beam Signals from Cell Membranes

Membranes ◽  
2021 ◽  
Vol 11 (8) ◽  
pp. 562
Author(s):  
Miliça Ristovski ◽  
Danny Farhat ◽  
Shelly Ellaine M. Bancud ◽  
Jyh-Yeuan Lee
Keyword(s):  
Membrane Proteins ◽  
Lipid Bilayers ◽  
Lipid Composition ◽  
Structural Integrity ◽  
Current Knowledge ◽  
Integral Membrane Proteins ◽  
Cellular Membranes ◽  
Cytoplasmic Proteins ◽  
Lipid Transporters

Lipid composition in cellular membranes plays an important role in maintaining the structural integrity of cells and in regulating cellular signaling that controls functions of both membrane-anchored and cytoplasmic proteins. ATP-dependent ABC and P4-ATPase lipid transporters, two integral membrane proteins, are known to contribute to lipid translocation across the lipid bilayers on the cellular membranes. In this review, we will highlight current knowledge about the role of cholesterol and phospholipids of cellular membranes in regulating cell signaling and how lipid transporters participate this process.

A Theoretical and Experimental Approach to E-pH Diagram for the Niobium-Water System

CORROSION ◽  
10.5006/3871 ◽  
2021 ◽  
Author(s):  
Rodney Santandrea ◽  
Simone BRASIL ◽  
Leila Reznik ◽  
Ladimir Carvalho ◽  
Luiz Miranda
Keyword(s):  
Experimental Approach ◽  
Ph Monitoring ◽  
Aqueous Media ◽  
Water System ◽  
Chemical Species ◽  
Polarization Curves ◽  
Buffer Solutions ◽  
Excellent Corrosion Resistance ◽  
Experimental Diagram ◽  
Selection Of

E-pH diagrams are usually built from thermodynamic databases available in the literature or from specific software. However, depending on the conditions and the chemical species defined for elaborating a diagram, it may present completely different immunity, passivation, and corrosion domains. In order to obtain a result closer to a real system, experimental E-pH diagrams can be built from polarization curves obtained in the evaluated conditions. This work discloses the construction of a diagram for the Nb-H<sub>2</sub>O system at 25°C from theoretical study and the specific selection of chemical species in the solutions through computer simulations. The polarization curves for the construction of the experimental diagram were gathered without the use of buffer solutions and under pH monitoring in the solution bulk throughout all assays. The methodology proposed was considered adequate since, from experimental data, a final result compatible with the classic diagram for the Nb-H<sub>2</sub>O system and the excellent corrosion resistance of niobium in aqueous media were achieved.

scholarly journals Formation of flavorant–propylene Glycol Adducts With Novel Toxicological Properties in Chemically Unstable E-Cigarette Liquids

2018 ◽  
Vol 21 (9) ◽  
pp. 1248-1258 ◽  
Author(s):  
Hanno C Erythropel ◽  
Sairam V Jabba ◽  
Tamara M DeWinter ◽  
Melissa Mendizabal ◽  
Paul T Anastas ◽  
...  
Keyword(s):  
Propylene Glycol ◽  
Electronic Cigarettes ◽  
Aqueous Media ◽  
Chemical Species ◽  
Resonance Spectroscopy ◽  
Reaction Products ◽  
Chemical Systems ◽  
Toxicological Effects ◽  
Wide Range ◽  
Irritant Receptors

Abstract Introduction “Vaping” electronic cigarettes (e-cigarettes) is increasingly popular with youth, driven by the wide range of available flavors, often created using flavor aldehydes. The objective of this study was to examine whether flavor aldehydes remain stable in e-cigarette liquids or whether they undergo chemical reactions, forming novel chemical species that may cause harm to the user. Methods Gas chromatography was used to determine concentrations of flavor aldehydes and reaction products in e-liquids and vapor generated from a commercial e-cigarette. Stability of the detected reaction products in aqueous media was monitored by ultraviolet spectroscopy and nuclear magnetic resonance spectroscopy, and their effects on irritant receptors determined by fluorescent calcium imaging in HEK-293T cells. Results Flavor aldehydes including benzaldehyde, cinnamaldehyde, citral, ethylvanillin, and vanillin rapidly reacted with the e-liquid solvent propylene glycol (PG) after mixing, and upward of 40% of flavor aldehyde content was converted to flavor aldehyde PG acetals, which were also detected in commercial e-liquids. Vaping experiments showed carryover rates of 50%–80% of acetals to e-cigarette vapor. Acetals remained stable in physiological aqueous solution, with half-lives above 36 hours, suggesting they persist when inhaled by the user. Acetals activated aldehyde-sensitive TRPA1 irritant receptors and aldehyde-insensitive TRPV1 irritant receptors. Conclusions E-liquids are potentially reactive chemical systems in which new compounds can form after mixing of constituents and during storage, as demonstrated here for flavor aldehyde PG acetals, with unexpected toxicological effects. For regulatory purposes, a rigorous process is advised to monitor the potentially changing composition of e-liquids and e-vapors over time, to identify possible health hazards. Implications This study demonstrates that e-cigarette liquids can be chemically unstable, with reactions occurring between flavorant and solvent components immediately after mixing at room temperature. The resulting compounds have toxicological properties that differ from either the flavorants or solvent components. These findings suggest that the reporting of manufacturing ingredients of e-liquids is insufficient for a safety assessment. The establishment of an analytical workflow to detect newly formed compounds in e-liquids and their potential toxicological effects is imperative for regulatory risk analysis.

scholarly journals The Structural Integrity of the Model Lipid Membrane during Induced Lipid Peroxidation: The Role of Flavonols in the Inhibition of Lipid Peroxidation

Antioxidants ◽  
2020 ◽  
Vol 9 (5) ◽  
pp. 430 ◽  
Author(s):  
Anja Sadžak ◽  
Janez Mravljak ◽  
Nadica Maltar-Strmečki ◽  
Zoran Arsov ◽  
Goran Baranović ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Structural Changes ◽  
Structural Integrity ◽  
Lipid Membrane ◽  
Membrane Properties ◽  
Structural Reorganization ◽  
Unsaturated Lipids ◽  
Oxidative Attack

The structural integrity, elasticity, and fluidity of lipid membranes are critical for cellular activities such as communication between cells, exocytosis, and endocytosis. Unsaturated lipids, the main components of biological membranes, are particularly susceptible to the oxidative attack of reactive oxygen species. The peroxidation of unsaturated lipids, in our case 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), induces the structural reorganization of the membrane. We have employed a multi-technique approach to analyze typical properties of lipid bilayers, i.e., roughness, thickness, elasticity, and fluidity. We compared the alteration of the membrane properties upon initiated lipid peroxidation and examined the ability of flavonols, namely quercetin (QUE), myricetin (MCE), and myricitrin (MCI) at different molar fractions, to inhibit this change. Using Mass Spectrometry (MS) and Fourier Transform Infrared Spectroscopy (FTIR), we identified various carbonyl products and examined the extent of the reaction. From Atomic Force Microscopy (AFM), Force Spectroscopy (FS), Small Angle X-Ray Scattering (SAXS), and Electron Paramagnetic Resonance (EPR) experiments, we concluded that the membranes with inserted flavonols exhibit resistance against the structural changes induced by the oxidative attack, which is a finding with multiple biological implications. Our approach reveals the interplay between the flavonol molecular structure and the crucial membrane properties under oxidative attack and provides insight into the pathophysiology of cellular oxidative injury.

Reducing lactose content of milk from livestock and humans via lactose imprinted poly(2-hydroxyethyl methacrylate-N-methacryloyl-i-aspartic acid) cryogels

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Kadir Erol ◽  
Gönül Arslan Akveran ◽  
Kazım Köse ◽  
Dursun Ali Köse
Keyword(s):  
Aspartic Acid ◽  
Structural Integrity ◽  
Lactose Intolerance ◽  
Aqueous Media ◽  
Surface Characteristics ◽  
Fold Increase ◽  
Hydroxyethyl Methacrylate ◽  
Micro Computed Tomography ◽  
Adsorption Parameters ◽  
Milk Samples

Abstract Lactase, which can cause lactose intolerance in its deficiency, is a vital enzyme concerning digestion. To overcome lactose intolerance for patients with digestion problem depending of this kind of issue, lactose in food should be removed. In this study, lactose imprinted poly(2-hydroxyethyl methacrylate-N-methacryloyl-l-aspartic acid), poly(HEMA-MAsp), cryogels were synthesized to reduce the amount of lactose content of milk samples. Occurrence of desired bounds, structural integrity, and surface characteristics were analyzed via Fourier transform infrared spectroscopy (FT-IR), nuclear magnetic resonance (NMR), scanning electron microscope (SEM), micro computed tomography (CT), and confocal microscope methods. Water retention characteristic were tested in solution with different electrolytic nature. Adsorption parameters were optimized in an aqueous medium. The adsorption performance of imprinted cryogels was studied in milk samples obtained from cow, sheep, goat, buffalo, and from human volunteers at different intervals after birth. Amount of lactose adsorbed in aqueous media and milk sample from humans were 322 (56.7%) and 179.5 (5.94%) mg lactose/g polymer, respectively. Selectivity studies revealed an approximately 8-fold increase in adsorption rate of molecularly imprinted cryogels as compared to that of nonimprinted cryogels. In addition, competitive adsorption was conducted using lactose-imprinted cryogels in aqueous media containing lactose, glucose, and galactose molecules resulting in adsorption rates of 220.56, 57.87, and 61.65 mg biomolecule/g polymer, respectively.

scholarly journals Application of Game Theory to Explore the Dynamics of Host−Pathogen Association in Phytobiomes

2018 ◽  
Vol 2 (3) ◽  
pp. 111-116 ◽  
Author(s):  
Man S. Kim ◽  
Huan Zhang ◽  
Won Bo Shim
Keyword(s):  
Game Theory ◽  
Big Data Analytics ◽  
Model Systems ◽  
Complex Nature ◽  
New Era ◽  
Host Pathogen ◽  
Single Host ◽  
Experimental Approaches ◽  
Improved Technology ◽  
Open Access Article

Recent advances in sequencing technology and big data analytics are moving plant pathology into a new era where we are now pursuing a deeper systems-level understanding of host–pathogen associations. For past several decades, scientists have predominantly tried to delineate and streamline these interactions into single pathogen–single host model systems, using reductionist experimental approaches. As many of us are aware, there have been several significant proposed ideas and models to help simplify and conceptualize the complex nature of associations that occur between plants and pathogens. However, equipped with vastly improved technology we now have opportunities to further explore multicomponent host–pathogen associations as well as microbe–microbe associations in phytobiomes and agroecosystems. Here, we would like to share our perspective on how game theory concepts could be adopted to study the dynamics of complex phytobiomes and to help us gain fresh and transformative insight. [Formula: see text] Copyright © 2018 The Author(s). This is an open-access article distributed under the CC BY-NC-ND 4.0 International license .

scholarly journals Recruitment of receptors at supported lipid bilayers promoted by the multivalent binding of ligand-modified unilamellar vesicles

2020 ◽  
Vol 11 (12) ◽  
pp. 3307-3315 ◽  
Author(s):  
Daniele Di Iorio ◽  
Yao Lu ◽  
Joris Meulman ◽  
Jurriaan Huskens
Keyword(s):  
Lipid Bilayers ◽  
Model Systems ◽  
Supported Lipid Bilayers ◽  
Biological Interactions ◽  
Unilamellar Vesicles ◽  
Multivalent Binding

The development of model systems that mimic biological interactions and allow the control of both receptor and ligand densities, is essential for a molecular understanding of biomolecular processes, such as the recruitment of receptors at interfaces.

Chemo-Hydrodynamic Patterns and Instabilities

2020 ◽  
Vol 52 (1) ◽  
pp. 531-555 ◽  
Author(s):  
A. De Wit
Keyword(s):  
Chemical Reactions ◽  
Chemical Species ◽  
Physical Property ◽  
Model Systems ◽  
Spatial Mobility ◽  
Convective Flows ◽  
Hydrodynamic Coupling ◽  
Theoretical Predictions ◽  
The Common ◽  
Nontrivial Coupling

By modifying a physical property of a solution like its density or viscosity, chemical reactions can modify and even trigger convective flows. These flows in turn affect the spatiotemporal distribution of the chemical species. A nontrivial coupling between reactions and flows then occurs. We present simple model systems of this chemo-hydrodynamic coupling. In particular, we illustrate the possibility of chemical reactions controlling or triggering viscous fingering, Rayleigh–Taylor, double-diffusive, and convective dissolution instabilities. We discuss laboratory experiments performed to study these phenomena and compare the experimental results to theoretical predictions. In each case we contrast the chemo-hydrodynamic patterns and instabilities with those that develop in nonreactive systems and unify the different dynamics in terms of the common features of the related spatial mobility profiles.

Photoluminescence Spectral Change in Self-Assembled Layered Titanate Oxide Intercalated with Eu3+

2006 ◽  
Vol 988 ◽  
Author(s):  
Shintaro Ida ◽  
Ugur Unal ◽  
Kazuyoshi Izawa ◽  
Chikako Ogata ◽  
Yasumichi Matsumoto
Keyword(s):  
Emission Intensity ◽  
Uv Light ◽  
Hole Burning ◽  
Water Molecules ◽  
Initial State ◽  
Excitation Spectra ◽  
Excitation Peak ◽  
State Of Water ◽  
Hydration State ◽  
Irradiation Wavelength

AbstractTitanate layered oxide intercalated with hydrated Eu3+ was synthesized by the electrostatic self-assembly deposition (ESD) method. The emission intensity of Eu3+ decreased rapidly with time during irradiation by UV light having energy higher than the band gap energy of the host Ti1.81O4 (TiO) layer. This is presumably due to the decrease in energy transfer from the host TiO layer to Eu3+ as a result of the change in the hydration state of water molecules surrounding Eu3+, which is caused by the hole produced in the TiO valence band. When irradiation was discontinued, the emission intensity gradually recovered. The recovery time increased when the water in the interlayer is removed by heat treatment. This indicates that the state of interlayer water changes during irradiation and returns to its initial state after discontinuation of irradiation. The excitation spectra changed drastically at any given wavelength upon irradiation with UV light. A comparison of the excitation spectra before and after irradiation reveals that only the excitation peak at around the irradiation wavelength decreased upon irradiation, as in the case of spectral hole burning. The hydration state of water molecules surrounding Eu3+ presumably changes depending on the irradiation wavelength.

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