scholarly journals Adhesion and Structural Changes of PEGylated Lipid Nanocarriers on Silica Surfaces

Physchem ◽  
2021 ◽  
Vol 1 (2) ◽  
pp. 133-151
Author(s):  
Philipp Grad ◽  
Katarina Edwards ◽  
Víctor Agmo Hernández
Keyword(s):  
Lipid Bilayers ◽  
Structural Changes ◽  
Lipid Membrane ◽  
Complete Separation ◽  
Supported Lipid Bilayers ◽  
Pegylated Liposomes ◽  
Silica Surfaces ◽  
Lipid Nanocarriers ◽  
Liquid Ordered ◽  
Pegylated Lipids

PEGylated lipid nanoparticles have a continuously expanding range of applications, particularly within pharmaceutical areas. Hereby, it is shown with the help of the Quartz Crystal Microbalance with Dissipation monitoring (QCM-D) and other surface sensitive techniques that, at room temperature, PEGylated liposomes and lipodisks adhere strongly to silica surfaces resulting in the displacement of the hydration layer of silica and the formation of immobilized nanoparticle films. Furthermore, it is shown that drastic changes in the structure of the immobilized films occur if the temperature is increased to >35 °C. Thus, intact immobilized PEGylated liposomes rupture and spread, even in the gel phase state; immobilized lipodisks undergo complete separation of their components (bilayer forming lipids and PEGylated lipids) resulting in a monolayer of adsorbed PEGylated lipids; and PEGylated supported lipid bilayers release part of the water trapped between the lipid membrane and the surface. It is hypothesized that these changes occur mainly due to the changes in the configuration of PEG chains and a drastic decrease of the affinity of the polymer for water. The observed phenomena can be applied, e.g., for the production of defect-free supported lipid bilayers in the gel or liquid ordered phase states.

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.

scholarly journals Structural Insights on Fusion Mechanisms of Extracellular Vesicles with Model Plasma Membrane

2020 ◽  
Author(s):  
Fabio Perissinotto ◽  
Valeria Rondelli ◽  
Beatrice Senigagliesi ◽  
Paola Brocca ◽  
László Almásy ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Extracellular Vesicles ◽  
Small Angle ◽  
Biochemical Characterization ◽  
The Body ◽  
Supported Lipid Bilayers ◽  
Force Microscopy ◽  
X Ray Scattering ◽  
Atomic Force ◽  
Liquid Ordered

AbstractExtracellular vesicles (EVs) represent a potent intercellular communication system. Within a lipid bilayer such small vesicles transport biomolecules between cells and throughout the body, strongly influencing the fate of recipient cells. Due to their specific biological functions they have been proposed as biomarkers for various diseases and as optimal candidates for therapeutic applications. Despite of their extreme biological relevance, the small size (30 to a few hundred nanometers in diameter) of EVs still poses a great challenge for their isolation, quantification and biophysical/biochemical characterization, therefore the complex network of EVs and cells as well as their interaction remains to be further revealed. Here we propose a multiscale platform based on Atomic Force Microscopy, Small Angle X-ray Scattering, Small Angle Neutron Scattering and Neutron Reflectometry to reveal structure-function correlations of purified EVs through the analysis of their interaction with model membrane systems, in form of both supported lipid bilayers and suspended unilamellar vesicles of variably complex composition. The analysis reveals a strong interaction of EVs with the model membranes and preferentially with liquid ordered raft-like lipid domains, and opens the way to understand uptake mechanisms in different vesicle to cell membrane relative compositions.

scholarly journals Correlative microscopy reveals the nanoscale morphology of E. coli-derived supported lipid bilayers

2021 ◽  
Author(s):  
Karan Bali ◽  
Zeinab Mohamed ◽  
Anna-Maria Pappa ◽  
Susan Daniel ◽  
Clemens F. Kaminski ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membrane ◽  
Lipid Vesicles ◽  
Outer Membrane Vesicles ◽  
Atomic Scale ◽  
Membrane Properties ◽  
Supported Lipid Bilayers ◽  
Structured Illumination ◽  
Structured Illumination Microscopy ◽  
Natural And Synthetic

Supported lipid bilayers (SLBs) made from reconstituted lipid vesicles are an important tool in molecular biology. A breakthrough in the field has come with the use of vesicles derived from cell membranes to form SLBs. These new supported bilayers, consisting both of natural and synthetic components, provide a physiologically relevant system on which to study protein-protein interactions as well as protein-ligand interactions and other lipid membrane properties. These complex bilayer systems hold promise but have not yet been fully characterised in terms of their composition, ratio of natural to synthetic component and membrane protein content. Here, we describe a method of correlative atomic force (AFM) with structured illumination microscopy (SIM) for the accurate mapping of complex lipid bilayers that consist of a synthetic fraction and a fraction of lipids derived from Escherichia coli outer membrane vesicles (OMVs). We exploit the enhanced resolution and molecular specificity that SIM can offer to identify areas of interest in these bilayers and the atomic scale resolution that the AFM provides to create detailed topography maps of the bilayers. We are thus able to understand the way in which the two different lipid fractions (natural and synthetic) mix within the bilayers, quantify the amount of bacterial membrane incorporated in the bilayer and directly visualise the interaction of these bilayers with bacteria-specific, membrane-binding proteins. Our work sets the foundation for accurately understanding the composition and properties of OMV-derived SLBs and establishes correlative AFM/ SIM as a method for characterising complex systems at the nanoscale.

scholarly journals Broadband Plasmon Waveguide Resonance Spectroscopy for Probing Biological Thin Films

2009 ◽  
Vol 63 (9) ◽  
pp. 1062-1067 ◽  
Author(s):  
Han Zhang ◽  
Kristina S. Orosz ◽  
Hiromi Takahashi ◽  
S. Scott Saavedra
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membrane ◽  
Resonance Wavelength ◽  
Supported Lipid Bilayers ◽  
Resonance Spectroscopy ◽  
Silica Layer ◽  
Transmembrane Receptors ◽  
Bk7 Glass ◽  
Biological Thin Films ◽  
Waveguide Resonance

A commercially available spectrometer has been modified to perform plasmon waveguide resonance (PWR) spectroscopy over a broad spectral bandwidth. When compared to surface plasmon resonance (SPR), PWR has the advantage of allowing measurements in both s- and p-polarizations on a waveguide surface that is silica or glass rather than a noble metal. Here the waveguide is a BK7 glass slide coated with silver and silica layers. The resonance wavelength is sensitive to the optical thickness of the medium adjacent to the silica layer. The sensitivity of this technique is characterized and compared with broadband SPR both experimentally and theoretically. The sensitivity of spectral PWR is comparable to that of spectral SPR for samples with refractive indices close to that of water. The hydrophilic surface of the waveguide allows supported lipid bilayers to be formed spontaneously by vesicle fusion; in contrast, the surface of an SPR chip requires chemical modification to create a supported lipid membrane. Broadband PWR spectroscopy should be a useful technique to study biointerfaces, including ligand binding to transmembrane receptors and adsorption of peripheral proteins on ligand-bearing membranes.

scholarly journals Proteins and Ions Compete for Membrane Interaction: the case of Lactadherin

2020 ◽  
Author(s):  
A. M. De Lio ◽  
D. Paul ◽  
R. Jain ◽  
J. H. Morrissey ◽  
T. V. Pogorelov
Keyword(s):  
Plasma Membrane ◽  
Blood Coagulation ◽  
Lipid Bilayers ◽  
Species Interactions ◽  
Drug Targets ◽  
Structural Changes ◽  
Lipid Membrane ◽  
Cell Damage ◽  
Experimental Studies ◽  
Coagulation Cascade

ABSTRACTCharged molecular species, such as ions, play a vital role in the life of the cell. In particular, divalent calcium ions (Ca2+) are critical for activating cellular membranes. Interactions between Ca2+ and anionic phosphatidylserine (PS) lipids result in structural changes of the plasma membrane and are vital for many signaling pathways, such as the tightly regulated blood coagulation cascade. Upon cell damage, PS lipids are externalized to the outer leaflet, where they are not only exposed to Ca2+, but also to proteins. Lactadherin is a glycoprotein, important for cell-adhesion, that can act as an anticoagulant. While a number of experimental studies have been performed on lactadherin’s C2 domain’s (LactC2) binding affinity for PS molecules, an atomistic description of LactC2 interactions with PS lipids in the plasma membrane is lacking. We performed extensive all-atom molecular dynamics simulations of mixed lipid bilayers and experimental characterization of LactC2-membrane interactions in the presence and absence of Ca2+ and characterized PS-Ca2+ and PS-LactC2 interactions to guide our understanding of how these interactions initiate and impede blood coagulation, respectively. The captured spontaneously formed long-lived PS-Ca2+ and PS-LactC2 complexes revealed that the protein side chains involved in PS-LactC2 interactions appear to be affected by the presence of Ca2+. The degree of LactC2 insertion into the lipid bilayer also appears to be dependent on the presence of Ca2+. Characterizing the interactions between Ca2+ and LactC2 with PS lipids can lead to a greater understanding of the activation and regulation of the blood coagulation cascade and of the basis of charged species interactions with the lipid membrane.STATEMENT OF SIGNIFICANCELactadherin plays an important role in cellular signaling including blood coagulation. Many of these processes involve lactadherin interacting with the lipids of the cell plasma membrane. Lactadherin acts as an anticoagulant and contributes to a number of health issues. Understanding the interactions that drive lactadherin’s anticoagulant properties can lead to potential new drug targets.

scholarly journals Antibody-Hapten Recognition at the Surface of Functionalized Liposomes Studied by SPR: Steric Hindrance of Pegylated Phospholipids in Stealth Liposomes Prepared for Targeted Radionuclide Delivery

2011 ◽  
Vol 2011 ◽  
pp. 1-9 ◽  
Author(s):  
Eliot. P. Botosoa ◽  
Mike Maillasson ◽  
Marie Mougin-Degraef ◽  
Patricia Remaud-Le Saëc ◽  
Jean-François Gestin ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Steric Hindrance ◽  
Lipid Fraction ◽  
Binding Kinetics ◽  
Specific Interactions ◽  
Pegylated Liposomes ◽  
Stealth Liposomes ◽  
Indium Complex ◽  
Pegylated Lipids ◽  
Pegylated Phospholipids

Targeted PEGylated liposomes could increase the amount of drugs or radionuclides delivered to tumor cells. They show favorable stability and pharmacokinetics, but steric hindrance of the PEG chains can block the binding of the targeting moiety. Here, specific interactions between an antihapten antibody (clone 734, specific for the DTPA-indium complex) and DTPA-indium-tagged liposomes were characterized by surface plasmon resonance (SPR). Non-PEGylated liposomes fused on CM5 chips whereas PEGylated liposomes did not. By contrast, both PEGylated and non-PEGylated liposomes attached to L1 chips without fusion. SPR binding kinetics showed that, in the absence of PEG, the antibody binds the hapten at the surface of lipid bilayers with the affinity of the soluble hapten. The incorporation of PEGylated lipids hinders antibody binding to extents depending on PEGylated lipid fraction and PEG molecular weight. SPR on immobilized liposomes thus appears as a useful technique to optimize formulations of liposomes for targeted therapy.

scholarly journals Structure, Formation, and Biological Interactions of Supported Lipid Bilayers (SLB) Incorporating Lipopolysaccharide

Coatings ◽  
2020 ◽  
Vol 10 (10) ◽  
pp. 981
Author(s):  
Palak Sondhi ◽  
Dhanbir Lingden ◽  
Keith J. Stine
Keyword(s):  
Lipid Bilayers ◽  
Lipid Membranes ◽  
Lipid Membrane ◽  
Biologically Active ◽  
Supported Lipid Bilayers ◽  
Biological Interactions ◽  
Relevant Model ◽  
Biologically Relevant ◽  
Model Lipid Membranes ◽  
Biomimetic Membrane

Biomimetic membrane systems play a crucial role in the field of biosensor engineering. Over the years, significant progress has been achieved creating artificial membranes by various strategies from vesicle fusion to Langmuir transfer approaches to meet an ever-growing demand for supported lipid bilayers on various substrates such as glass, mica, gold, polymer cushions, and many more. This paper reviews the diversity seen in the preparation of biologically relevant model lipid membranes which includes monolayers and bilayers of phospholipid and other crucial components such as proteins, characterization techniques, changes in the physical properties of the membranes during molecular interactions and the dynamics of the lipid membrane with biologically active molecules with special emphasis on lipopolysaccharides (LPS).

Quaternary Amine-Terminated Quantum Dots Induce Structural Changes to Supported Lipid Bilayers

Langmuir ◽  
2018 ◽  
Vol 34 (41) ◽  
pp. 12369-12378 ◽  
Author(s):  
Arielle C. Mensch ◽  
Joseph T. Buchman ◽  
Christy L. Haynes ◽  
Joel A. Pedersen ◽  
Robert J. Hamers
Keyword(s):  
Quantum Dots ◽  
Lipid Bilayers ◽  
Structural Changes ◽  
Supported Lipid Bilayers ◽  
Quaternary Amine
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