(Cryo)Transmission Electron Microscopy of Phospholipid Model Membranes Interacting with Amphiphilic and Polyphilic Molecules

Meister, Annette; Blume, Alfred

doi:10.3390/polym9100521

Cited by 24 publications

(14 citation statements)

References 99 publications

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“…All azidolipid/DPPC suspensions showed the formation of collapsed vesicles in a size range between 100 and 200 nm (Figure B,D,F,H). These vesicles are folded because of the drying procedure during sample preparation . Similar aggregate shapes could be observed for azidolipid/DMPC suspensions (Figure A,C,E,G).…”

Section: Resultssupporting

confidence: 71%

Azide-Modified Membrane Lipids: Miscibility with Saturated Phosphatidylcholines

et al. 2019

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In this study, we describe the miscibility of four azide-modified membrane phospholipids (azidolipids) with conventional phospholipids. The azidolipids bear an azide group at different positions of the sn-1 or sn-2 alkyl chain and they further differ in the type of linkage (ester vs ether) of the sn-2 alkyl chain. Investigations regarding the miscibility of the azidolipids with bilayer-forming phosphatidylcholines will evaluate lipid mixtures that are suitable for the production of stable azidolipid-doped liposomes. These vesicles then serve as model membranes for the incorporation of model peptides or proteins in the future. The miscibility of both types of phospholipids was studied by calorimetric assays, electron microscopy, small-angle X-ray scattering, infrared spectroscopy, and dynamic light scattering to provide a complete biophysical characterization of the mixed systems.

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Section: Resultssupporting

confidence: 71%

Azide-Modified Membrane Lipids: Miscibility with Saturated Phosphatidylcholines

et al. 2019

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“…The mechanism for the gelation of microscale blood cells (as well as nanoscale vesicles) by hmC has been hypothesized to involve hydrophobic interactions. − Specifically, some of the hydrophobic tails on hmC are expected to embed in the lipid membranes of blood cells (the interiors of these bilayer membranes are hydrophobic due to the lipid tails being located there − ). Through such hydrophobic anchoring, each hmC chain is expected to bind to multiple cells, i.e., the chains will bridge adjacent cells.…”

Section: Introductionmentioning

confidence: 99%

How Do Amphiphilic Biopolymers Gel Blood? An Investigation Using Optical Microscopy

2020

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Amphiphilic biopolymers such as hydrophobically modified chitosan (hmC) have been shown to convert liquid blood into elastic gels. This interesting property could make hmC useful as a hemostatic agent in treating severe bleeding. The mechanism for blood gelling by hmC is believed to involve polymer–cell self-assembly, i.e., insertion of hydrophobic side chains from the polymer into the lipid bilayers of blood cells, thereby creating a network of cells bridged by hmC. Here, we probe the above mechanism by studying dilute mixtures of blood cells and hmC in situ using optical microscopy. Our results show that the presence of hydrophobic side chains on hmC induces significant clustering of blood cells. The extent of clustering is quantified from the images in terms of the area occupied by the 10 largest clusters. Clustering increases as the fraction of hydrophobic side chains increases; conversely, clustering is negligible in the case of the parent chitosan that lacks hydrophobes. Moreover, the longer the hydrophobic side chains, the greater the clustering (i.e., C12 > C10 > C8 > C6). Clustering is negligible at low hmC concentrations but becomes substantial above a certain threshold. Finally, clustering due to hmC can be reversed by adding the supramolecule α-cyclodextrin, which is known to capture hydrophobes in its binding pocket. Overall, the results from this work are broadly consistent with the earlier mechanism, albeit with a few modifications.

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“…The TEM images of stained samples are not unproblematic and, e.g., an effect of the staining agent on the shape of aggregates could occur or artifacts could be produced during sample preparation (drying process). , Therefore, also to further clarify the shape of aggregates formed, we additionally prepared cryo-EM images of vitrified specimens of both lipid mixtures. The results are shown in Figure C,D and in the Supporting Information (Figures S1 and S2).…”

Section: Results and Discussionmentioning

confidence: 99%

Tuning the Thickness of a Biomembrane by Stapling Diamidophospholipids with Bolalipids

Drescher

Meister²,

Hause

et al. 2020

Langmuir

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In a biological membrane, proteins require specific lipids of distinctive length and chain saturation surrounding them. The active tuning of the membrane thickness therefore opens new possibilities in the study and manipulation of membrane proteins. Here, we introduce the concept of stapling phospholipids to different degrees of interdigitation depth by mixing 1,3-diamidophospholipids with single-chain bolalipids. The mixed membranes were studied by calorimetric assays, electron microscopy, X-ray, and infrared measurements to provide a complete biophysical characterization of membrane stapling. The matching between the diamidophospholipids and the bolalipids can be so strong as to completely induce a new phase that is more stable than the gel phase of the individual components.

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(Cryo)Transmission Electron Microscopy of Phospholipid Model Membranes Interacting with Amphiphilic and Polyphilic Molecules

Cited by 24 publications

References 99 publications

Azide-Modified Membrane Lipids: Miscibility with Saturated Phosphatidylcholines

Azide-Modified Membrane Lipids: Miscibility with Saturated Phosphatidylcholines

How Do Amphiphilic Biopolymers Gel Blood? An Investigation Using Optical Microscopy

Tuning the Thickness of a Biomembrane by Stapling Diamidophospholipids with Bolalipids

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