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Giant vesicles are widely used as a model membrane system, both for basic biological systems and for their promising applications in the development of smart materials and cell mimetics, as well as in driving new technologies in synthetic biology and for the cosmetics and pharmaceutical industry. The reader is guided to use giant vesicles, from the formation of simple membrane platforms to advanced membrane and cell system models. It also includes fundamentals for understanding lipid or polymer membrane structure, properties and behavior. Every chapter includes ideas for further applications and discussions on the implications of the observed phenomena towards understanding membrane-related processes. The Giant Vesicle Book is meant to be a road companion, a trusted guide for those making their first steps in this field as well as a source of information required by experts. Key Features • A complete summary of the field, covering fundamental concepts, practical methods, core theory, and the most promising applications • A start-up package of theoretical and experimental information for newcomers in the field • Extensive protocols for establishing the required preparations and assays • Tips and instructions for carefully performing and interpreting measurements with giant vesicles or for observing them, including pitfalls • Approaches developed for investigating giant vesicles as well as brief overviews of previous studies implementing the described techniques • Handy tables with data and structures for ready reference Part I: The making of Chapter 1 Preparation methods for giant unilamellar vesicles - Rumiana Dimova, Pasquale Stano, Carlos M. Marques and Peter Walde Chapter 2 Preparation and properties of giant plasma membrane vesicles and giant unilamellar vesicles from natural membranes - Joseph H. Lorent and Ilya Levental Chapter 3 Protein reconstitution in giant vesicles - Matthias Garten, Daniel Lévy and Patricia Bassereau　 Chapter 4 GUVs with cytoskeleton - Tobias Härtel and Petra Schwille Part II: Giant vesicles theoretically and in silico Chapter 5 Understanding giant vesicles – a theoretical perspective - Reinhard Lipowsky Chapter 6 Simulating membranes, vesicles, and cells - Thorsten Auth, Dmitry A. Fedosov and Gerhard Gompper Chapter 7 Theory of vesicle dynamics in flow and electric fields - Petia M. Vlahovska and Chaouqi Misbah Chapter 8 Particle-membrane interactions - Jaime Agudo-Canalejo, Reinhard Lipowsky Chapter 9 Theory of polymer-membrane interactions - Fabrice Thalmann and Carlos M. Marques Part III: GUV-based techniques and what one can learn from them Chapter 10 Application of optical microscopy techniques on giant unilamellar vesicles - Luis A. Bagatolli Chapter 11 Mechanics assays of synthetic lipid membranes based on micropipette aspiration - Elisa Parra and David Needham Chapter 12 Atomic force microscopy of giant unilamellar vesicles - Andreas Janshoff Chapter 13 Manipulation and biophysical characterization of GUVs with an optical stretcher - Gheorghe Cojoc, Antoine Girot, Ulysse Delabre and Jochen Guck Chapter 14 Vesicle fluctuation analysis - John Hjort Ipsen, Allan Grønhøj Hansen and Tripta Bhatia Chapter 15 Using electric fields to assess membrane material properties in GUVs - Rumiana Dimova and　　Karin A. Riske Chapter 16 Creating membrane nanotubes from GUVs - Coline Prévost, Mijo Simunovic and Patricia Bassereau Chapter 17 Measuring GUV adhesion - Kheya Sengupta and Ana Smith Chapter 18 Phase diagrams and tie lines in GUVs - Matthew C. Blosser, Caitlin Cornell, Scott P. Rayermann and Sarah L. Keller Chapter 19 Vesicle dynamics in flow: an experimental approach - Victor Steinberg and Michael Levant Chapter 20 Membrane permeability measurements - Begoña Ugarte-Uribe, Ana J. García-Sáez and Mireille M. A. E. Claessens Part IV: GUVs as membrane interaction platforms Chapter 21 - Lipid and protein mobility in GUVs - Begoña Ugarte-Uribe, Kushal Kumar Das and Ana J. García-Sáez Chapter 22 Shining light on membranes - Rosangela Itri, Carlos M. Marques and Mauricio S. Baptista Chapter 23 Protein-membrane interactions - Eva M Schmid and Daniel A Fletcher Chapter 24 Effects of antimicrobial peptides and detergents on GUVs - Karin A. Riske Chapter 25 Lipid-polymer interactions: effect on GUVs shapes and behavior - Brigitte Pépin-Donat, François Quemeneur and Clément Campillo Part V: GUVs as complex membrane containers Chapter 26 Polymersomes - Praful Nair, David Christian and Dennis E. Discher Chapter 27 Giant hybrid polymer/lipid vesicles - Thi Phuong Tuyen Dao, Khalid Ferji, Fabio Fernandes, Manuel Prieto, Sébastien Lecommandoux, Emmanuel Ibarboure, Olivier Sandre and Jean-François Le Meins Chapter 28 Giant unilamellar vesicles: from protocell models to the construction of minimal cells - Masayuki Imai and Peter Walde Chapter 29 Encapsulation of aqueous two-phase systems and gels within giant lipid vesicles - Allyson M. Marianelli and Christine D. Keating Chapter 30 Droplet-supported giant lipid vesicles as compartments for synthetic biology - Johannes P. Frohnmayer, Marian Weiss, Lucia T. Benk, Jan-Willi Janiesch, Barbara Haller, Rafael B. Lira, Rumiana Dimova, Ilia Plazman and Joachim P. Spatz Appendices Appendix 1 List of lipids and physical constants of lipid bilayers Appendix 2 List of membrane dyes and fluorescent groups conjugated to lipids Appendix 3 List of detergents Appendix 4 List of water-soluble dyes or their fluorescent groups and their structures Rumiana Dimova leads an experimental lab in biophysics at the Max Planck Institute of Colloids and Interfaces in Potsdam, Germany. She has been working with giant vesicles already from the beginning of her scientific career. After being introduced into the magic of their preparation during her studies as a student in Bulgaria, she remained fascinated by their application and over the years pursued a variety of projects employing giant vesicles as a platform to develop new methods for the biophysical characterization of membranes and processes involving them. Until now, these studies have resulted in more than hundred peer-reviewed publications. Recently, she was also awarded the Emmy Noether distinction for women in physics of the European Physical Society. Carlos Marques , a CNRS senior scientist, founded the MCube group at the Charles Sadron Institute in Strasbourg, France, where he gears experimental and theoretical research towards the understanding of the physical properties of self-assembled lipid bilayers. Trained as a polymer theoretician, Carlos first got interested in membranes because they interact with polymers and published the first prediction for the membrane changes expected when polymers adsorb on lipid bilayers. He then expanded the scope of his group to include experiments and numerical simulations, and has now published many papers based on research with giant unilamellar vesicles, including the first study of lipid oxidation in GUVs and the discovery of the so-called PVA method for vesicle growth.

Production of lactic acid bacteria starters for manufacturing food, probiotic, and chemical products requires the application of successive steps: fermentation, concentration, stabilization, and storage. Despite process optimization, losses of bacterial viability and functional activities are observed after stabilization and storage steps due to cell exposure to environmental stresses (thermal, osmotic, mechanical, and oxidative). Bacterial membrane is the primary target for injury and its damage is highly dependent on its physical properties and lipid organization. Membrane fluidity is a key property for maintaining cell functionality, and depends on lipid composition and cell environment. Extensive evidence has been reported on changes in membrane fatty acyl chains when modifying fermentation conditions. However, a deep characterization of membrane physical properties and their evolution following production processes is scarcely reported. Therefore, the aims of this mini-review are (i) to define the membrane fluidity and the methods used to assess it and (ii) to summarize the effect of environmental conditions on membrane fluidity and the resulting impact on the resistance of lactic acid bacteria to the stabilization processes. This will make it possible to highlight existing gaps of knowledge and opens up novel approaches for future investigations.

Lipid composition determines membrane properties, and cholesterol plays a major role in this determination as it regulates membrane fluidity and permeability, as well as induces the formation of coexisting phases and domains in the membrane. Biological membranes display a very diverse lipid composition, the lateral organization of which plays a crucial role in regulating a variety of membrane functions. We hypothesize that, during biological evolution, membranes with a particular cholesterol content were selected to perform certain functions in the cells of eukaryotic organisms. In this review, we discuss the major membrane properties induced by cholesterol, and their relationship to certain membrane functions.

Background Nanoplastics have been recently found widely distributed in our natural environment where ubiquitously bacteria are major participants in various material cycles. Understanding how nanoplastics interact with bacterial cell membrane is critical to grasp their uptake processes as well as to analyze their associated risks in ecosystems and human microflora. However, little is known about the detailed interaction of differentially charged nanoplastics with bacteria. The present work experimentally and theoretically demonstrated that nanoplastics enter into bacteria depending on the surface charges and cell envelope structural features, and proved the shielding role of membrane lipids against nanoplastics. Results Positively charged polystyrene nanoplastics (PS-NH 2 , 80 nm) can efficiently translocate across cell membranes, while negatively charged PS (PS-COOH) and neutral PS show almost no or much less efficacy in translocation. Molecular dynamics simulations revealed that the PS-NH 2 displayed more favourable electrostatic interactions with bacterial membranes and was subjected to internalisation through membrane penetration. The positively charged nanoplastics destroy cell envelope of Gram-positive B. subtilis by forming membrane pore, while enter into the Gram-negative E. coli with a relatively intact envelope. The accumulated positively charged nanoplastics conveyed more cell stress by inducing a higher level of reactive oxygen species (ROS). However, the subsequently released membrane lipid-coated nanoplastics were nearly nontoxic to cells, and like wise, stealthy bacteria wrapped up with artifical lipid layers became less sensitive to the positively charged nanoplastics, thereby illustrating that the membrane lipid can shield the strong interaction between the positively charged nanoplastics and cells. Conclusions Our findings elucidated the molecular mechanism of nanoplastics’ interaction and accumulation within bacteria, and implied the shielding and internalization effect of membrane lipid on toxic nanoplastics could promote bacteria for potential plastic bioremediation. Graphical Abstract

The quantification of membrane-associated biomolecular interactions is crucial to our understanding of various cellular processes. State-of-the-art single-molecule approaches rely largely on the addition of fluorescent labels, which complicates the quantification of the involved stoichiometries and dynamics because of low temporal resolution and the inherent limitations associated with labeling efficiency, photoblinking and photobleaching. Here, we demonstrate dynamic mass photometry, a method for label-free imaging, tracking and mass measurement of individual membrane-associated proteins diffusing on supported lipid bilayers. Application of this method to the membrane remodeling GTPase, dynamin-1, reveals heterogeneous mixtures of dimer-based oligomers, oligomer-dependent mobilities, membrane affinities and (dis)association of individual complexes. These capabilities, together with assay-based advances for studying integral membrane proteins, will enable the elucidation of biomolecular mechanisms in and on lipid bilayers.Dynamic mass photometry allows label-free tracking and mass measurement of individual membrane-associated proteins diffusing on supported lipid bilayers. The approach can be used to monitor dynamic (dis)assembly of protein complexes.

Hierarchical organization of integral membrane proteins (IMP) and lipids at the membrane is essential for regulating myriad downstream signaling. A quantitative understanding of these processes requires both detections of oligomeric organization of IMPs and lipids directly from intact membranes and determination of key membrane components and properties that regulate them. Addressing this, we have developed a platform that enables native mass spectrometry (nMS) analysis of IMP–lipid complexes directly from intact and customizable lipid membranes. Both the lipid composition and membrane properties (such as curvature, tension, and fluidity) of these bilayers can be precisely customized to a target membrane. Subsequent direct nMS analysis of these intact proteolipid vesicles can yield the oligomeric states of the embedded IMPs, identify bound lipids, and determine the membrane properties that can regulate the observed IMP–lipid organization. Applying this method, we show how lipid binding regulates neurotransmitter release and how membrane composition regulates the functional oligomeric state of a transporter. Editor summary: A native-mass-spectrometry-based approach analyzes integral membrane protein–lipid complexes directly from near-physiological membrane conditions, providing information about protein oligomeric states, lipid identities, and membrane properties.

Exosomes are lipid bilayer membrane vesicles and are emerging as competent nanocarriers for drug delivery. The clinical translation of exosomes faces many challenges such as massive production, standard isolation, drug loading, stability and quality control. In recent years, artificial exosomes are emerging based on nanobiotechnology to overcome the limitations of natural exosomes. Major types of artificial exosomes include ‘nanovesicles (NVs)’, ‘exosome-mimetic (EM)’ and ‘hybrid exosomes (HEs)’, which are obtained by top-down, bottom-up and biohybrid strategies, respectively. Artificial exosomes are powerful alternatives to natural exosomes for drug delivery. Here, we outline recent advances in artificial exosomes through nanobiotechnology and discuss their strengths, limitations and future perspectives. The development of artificial exosomes holds great values for translational nanomedicine.

Background The reconstitution of membrane proteins and complexes into nanoscale lipid bilayer structures has contributed significantly to biochemical and biophysical analyses. Current methods for performing such reconstitutions entail an initial detergent-mediated step to solubilize and isolate membrane proteins. Exposure to detergents, however, can destabilize many membrane proteins and result in a loss of function. Amphipathic copolymers have recently been used to stabilize membrane proteins and complexes following suitable detergent extraction. However, the ability of these copolymers to extract proteins directly from native lipid bilayers for subsequent reconstitution and characterization has not been explored. Results The styrene-maleic acid (SMA) copolymer effectively solubilized membranes of isolated mitochondria and extracted protein complexes. Membrane complexes were reconstituted into polymer-bound nanoscale discs along with endogenous lipids. Using respiratory Complex IV as a model, these particles were shown to maintain the enzymatic activity of multicomponent electron transporting complexes. Conclusions We report a novel process for reconstituting fully operational protein complexes directly from cellular membranes into nanoscale lipid bilayers using the SMA copolymer. This facile, single-step strategy obviates the requirement for detergents and yields membrane complexes suitable for structural and functional studies.

Carboxylic acids are an attractive biorenewable chemical. However, like many other fermentatively produced compounds, they are inhibitory to the biocatalyst. An understanding of the mechanism of toxicity can aid in mitigating this problem. Here, we show that hexanoic and octanoic acids are completely inhibitory to Escherichia coli MG1655 in minimal medium at a concentration of 40 mM, while decanoic acid was inhibitory at 20 mM. This growth inhibition is pH-dependent and is accompanied by a significant change in the fluorescence polarization (fluidity) and integrity. This inhibition and sensitivity to membrane fluidization, but not to damage of membrane integrity, can be at least partially mitigated during short-term adaptation to octanoic acid. This short-term adaptation was accompanied by a change in membrane lipid composition and a decrease in cell surface hydrophobicity. Specifically, the saturated/unsaturated lipid ratio decreased and the average lipid length increased. A fatty acid-producing strain exhibited an increase in membrane leakage as the product titer increased, but no change in membrane fluidity. These results highlight the importance of the cell membrane as a target for future metabolic engineering efforts for enabling resistance and tolerance of desirable biorenewable compounds, such as carboxylic acids. Knowledge of these effects can help in the engineering of robust biocatalysts for biorenewable chemicals production.

In order to compete with petroleum-based fuel and chemicals, engineering a robust biocatalyst that can convert renewable feedstocks into biorenewable chemicals, such as carboxylic acids, is increasingly important. However, product toxicity is often problematic. In this study, the toxicity of the carboxylic acids hexanoic, octanoic, and decanoic acid on Saccharomyces cerevisiae was investigated, with a focus on octanoic acid. These compounds are completely inhibitory at concentrations of magnitude 1 mM, and the toxicity increases as chain length increases and as media pH decreases. Transciptome analysis, reconstruction of gene regulatory network, and network component analysis suggested decreased membrane integrity during challenge with octanoic acid. This was confirmed by quantification of dose-dependent and chain length-dependent induction of membrane leakage, though membrane fluidity was not affected. This induction of membrane leakage could be significantly decreased by a period of pre-adaptation, and this pre-adaptation was accompanied by increased oleic acid content in the membrane, significantly increased production of saturated lipids relative to unsaturated lipids, and a significant increase in the average lipid chain length in the membrane. However, during adaptation cell surface hydrophobicity was not altered. The supplementation of oleic acid to the medium not only elevated the tolerance of yeast cells to octanoic acid but also attenuated the membrane leakiness. However, while attempts to mimic the oleic acid supplementation effects through expression of the Trichoplusia ni acyl-CoA Δ9 desaturase OLE1(TniNPVE desaturase) were able to increase the oleic acid content, the magnitude of the increase was not sufficient to reproduce the supplementation effect and increase octanoic acid tolerance. Similarly, introduction of cyclopropanated fatty acids through expression of the Escherichia coli cfa gene was not helpful for tolerance. Thus, we have provided quantitative evidence that carboxylic acids damage the yeast membrane and that manipulation of the lipid content of the membrane can increase tolerance, and possibly production, of these valuable products.