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Phase separation in polymer-based biomimetic structures containing planar membranes. Biointerphases 2022; 17:060802. [PMID: 36575113 DOI: 10.1116/6.0002078] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/28/2022] Open
Abstract
Phase separation in biological membranes is crucial for proper cellular functions, such as signaling and trafficking, as it mediates the interactions of condensates on membrane-bound organelles and transmembrane transport to targeted destination compartments. The separation of a lipid bilayer into phases and the formation of lipid rafts involve the restructuring of molecular localization, their immobilization, and local accumulation. By understanding the processes underlying the formation of lipid rafts in a cellular membrane, it is possible to reconstitute this phenomenon in synthetic biomimetic membranes, such as hybrids of lipids and polymers or membranes composed solely of polymers, which offer an increased physicochemical stability and unlimited possibilities of chemical modification and functionalization. In this article, we relate the main lipid bilayer phase transition phenomenon with respect to hybrid biomimetic membranes, composed of lipids mixed with polymers, and fully synthetic membranes. Following, we review the occurrence of phase separation in biomimetic hybrid membranes based on lipids and/or direct lipid analogs, amphiphilic block copolymers. We further exemplify the phase separation and the resulting properties and applications in planar membranes, free-standing and solid-supported. We briefly list methods leading to the formation of such biomimetic membranes and reflect on their improved overall stability and influence on the separation into different phases within the membranes. Due to the importance of phase separation and compartmentalization in cellular membranes, we are convinced that this compiled overview of this phenomenon will be helpful for any researcher in the biomimicry area.
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Mikhailov IV, Darinskii AA, Birshtein TM. Bending Rigidity of Branched Polymer Brushes with Finite Membrane Thickness. POLYMER SCIENCE SERIES C 2022. [DOI: 10.1134/s1811238222700199] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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Abstract
Hierarchic self-assembly underpins much of the form and function seen in synthetic or biological soft materials. Lipids are paramount examples, building themselves in nature or synthetically in a variety of meso/nanostructures. Synthetic block copolymers capture many of lipid's structural and functional properties. Lipids are typically biocompatible and high molecular weight polymers are mechanically robust and chemically versatile. The development of new materials for applications like controlled drug/gene/protein delivery, biosensors, and artificial cells often requires the combination of lipids and polymers. The emergent composite material, a "polymer-lipid hybrid membrane", displays synergistic properties not seen in pure components. Specific examples include the observation that hybrid membranes undergo lateral phase separation that can correlate in registry across multiple layers into a three-dimensional phase-separated system with enhanced permeability of encapsulated drugs. It is timely to underpin these emergent properties in several categories of hybrid systems ranging from colloidal suspensions to supported hybrid films. In this review, we discuss the form and function of a vast number of polymer-lipid hybrid systems published to date. We rationalize the results to raise new fundamental understanding of hybrid self-assembling soft materials as well as to enable the design of new supramolecular systems and applications.
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Affiliation(s)
- Yoo Kyung Go
- Department of Materials Science and Engineering, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States
| | - Cecilia Leal
- Department of Materials Science and Engineering, University of Illinois at Urbana─Champaign, Urbana, Illinois 61801, United States
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Jbeily M, Kressler J. Fluorophilicity and lipophilicity of fluorinated rhodamines determined by their partition coefficients in biphasic solvent systems. J Fluor Chem 2017. [DOI: 10.1016/j.jfluchem.2016.11.018] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023]
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Scholtysek P, Shah SWH, Müller SS, Schöps R, Frey H, Blume A, Kressler J. Unusual triskelion patterns and dye-labelled GUVs: consequences of the interaction of cholesterol-containing linear-hyperbranched block copolymers with phospholipids. SOFT MATTER 2015; 11:6106-6117. [PMID: 26133098 DOI: 10.1039/c5sm01017a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Cholesterol (Ch) linked to a linear-hyperbranched block copolymer composed of poly(ethylene glycol) (PEG) and poly(glycerol) (hbPG) was investigated for its membrane anchoring properties. Two polyether-based linear-hyperbranched block copolymers with and without a covalently attached rhodamine fluorescence label (Rho) were employed (Ch-PEG30-b-hbPG23 and Ch-PEG30-b-hbPG17-Rho). Compression isotherms of co-spread 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) or 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) with the respective polymers were measured on the Langmuir trough and the morphology development of the liquid-condensed (LC) domains was studied by epi-fluorescence microscopy. LC domains were strongly deformed due to the localization of the polymers at the domain interface, indicating a line activity for both block copolymers. Simultaneously, it was observed that the presence of the fluorescence label significantly influences the domain morphology, the rhodamine labelled polymer showing higher line activity. Adsorption isotherms of the polymers to the water surface or to monolayers of DPPC and 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC), respectively, were collected. Again the rhodamine labelled polymer showed higher surface activity and a higher affinity for insertion into lipid monolayers, which was negligibly affected when the sub-phase was changed to aqueous sodium chloride solution or phosphate buffer. Calorimetric investigations in bulk confirmed the results found using tensiometry. Confocal laser scanning microscopy (CLSM) of giant unilamellar vesicles (GUVs) also confirmed the polymers' fast adsorption to and insertion into phospholipid membranes.
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Affiliation(s)
- Peggy Scholtysek
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, von-Danckelmann-Platz 4, D-06120 Halle (Saale), Germany.
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Mohr K, Müller SS, Müller LK, Rusitzka K, Gietzen S, Frey H, Schmidt M. Evaluation of multifunctional liposomes in human blood serum by light scattering. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:14954-14962. [PMID: 25469945 DOI: 10.1021/la502926e] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
To overcome the limited functionality of "stealth" lipids based on linear poly(ethylene glycol) (PEG) chains, hyperbranched polyether-based lipids that bear multiple hydroxyl groups for further chemical modification may be a suitable replacement. This study focuses on the development and characterization of "stealth" liposomes modified with a novel hyperbranched polyglycerol lipid (cholesterol-PEG30-hbPG23). An emphasis was placed on the stability of these liposomes in comparison to those containing a linear PEG derivative (cholesterol-PEG44) directly in human blood serum, characterized via dynamic light scattering (DLS). Polymer lipid contents were varied between 0 and 30 mol %, resulting in liposomes with sizes between 150 and 80 nm in radius, depending on the composition. DLS analysis showed no aggregation inducing interactions between serum components and liposomes containing 10-30 mol % of the hyperbranched lipid. In contrast, liposomes functionalized with comparable amounts of linear PEG exhibited aggregate formation in the size range of 170-330 nm under similar conditions. In addition to DLS, cryo-transmission electron microscopy (TEM) was employed for all liposome samples to prove the formation of unilamellar vesicles. These results demonstrate the outstanding potential of the introduction of hyperbranched polyglycerol into liposomes to stabilize the assemblies against aggregation while providing additional functionalization sites.
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Affiliation(s)
- Kristin Mohr
- Institute of Physical Chemistry, Johannes Gutenberg University Mainz , Welderweg 11, 55128 Mainz, Germany
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Schwieger C, Achilles A, Scholz S, Rüger J, Bacia K, Saalwaechter K, Kressler J, Blume A. Binding of amphiphilic and triphilic block copolymers to lipid model membranes: the role of perfluorinated moieties. SOFT MATTER 2014; 10:6147-6160. [PMID: 24942348 DOI: 10.1039/c4sm00830h] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
A novel class of symmetric amphi- and triphilic (hydrophilic, lipophilic, fluorophilic) block copolymers has been investigated with respect to their interactions with lipid membranes. The amphiphilic triblock copolymer has the structure PGMA(20)-PPO(34)-PGMA(20) (GP) and it becomes triphilic after attaching perfluoroalkyl moieties (F9) to either end which leads to F(9)-PGMA(20)-PPO(34)-PGMA(20)-F(9) (F-GP). The hydrophobic poly(propylene oxide) (PPO) block is sufficiently long to span a lipid bilayer. The poly(glycerol monomethacrylate) (PGMA) blocks have a high propensity for hydrogen bonding. The hydrophobic and lipophobic perfluoroalkyl moieties have the tendency to phase segregate in aqueous as well as in hydrocarbon environments. We performed differential scanning calorimetry (DSC) measurements on polymer bound lipid vesicles under systematic variation of the bilayer thickness, the nature of the lipid headgroup, and the polymer concentration. The vesicles were composed of phosphatidylcholines (DMPC, DPPC, DAPC, DSPC) or phosphatidylethanolamines (DMPE, DPPE, POPE). We showed that GP as well as F-GP binding have membrane stabilizing and destabilizing components. PPO and F9 blocks insert into the hydrophobic part of the membrane concomitantly with PGMA block adsorption to the lipid headgroup layer. The F9 chains act as additional membrane anchors. The insertion of the PPO blocks of both GP and F-GP could be proven by 2D-NOESY NMR spectroscopy. By fluorescence microscopy we show that F-GP binding increases the porosity of POPC giant unilamellar vesicles (GUVs), allowing the influx of water soluble dyes as well as the translocation of the complete triphilic polymer and its accumulation at the GUV surface. These results open a new route for the rational design of membrane systems with specific properties.
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Affiliation(s)
- Christian Schwieger
- Institute of Chemistry, Martin Luther University Halle-Wittenberg, 06120 Halle (Saale), Germany.
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Fritz T, Hirsch M, Richter FC, Müller SS, Hofmann AM, Rusitzka KAK, Markl J, Massing U, Frey H, Helm M. Click Modification of Multifunctional Liposomes Bearing Hyperbranched Polyether Chains. Biomacromolecules 2014; 15:2440-8. [DOI: 10.1021/bm5003027] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Thomas Fritz
- Institute
of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, Staudingerweg
5, 55122 Mainz, Germany
| | - Markus Hirsch
- Institute
of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, Staudingerweg
5, 55122 Mainz, Germany
| | - Felix C. Richter
- Institute
of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, Staudingerweg
5, 55122 Mainz, Germany
| | - Sophie S. Müller
- Institute
of Organic Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14, 55122 Mainz, Germany
- Graduate School MAINZ, Staudingerweg
9, 55128 Mainz, Germany
| | - Anna M. Hofmann
- Institute
of Organic Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14, 55122 Mainz, Germany
| | - Kristiane A. K. Rusitzka
- Institute
of Zoology, Johannes Gutenberg-University Mainz, J.-J. Becher-Weg
7, 55122 Mainz, Germany
| | - Jürgen Markl
- Institute
of Zoology, Johannes Gutenberg-University Mainz, J.-J. Becher-Weg
7, 55122 Mainz, Germany
| | - Ulrich Massing
- Department
of Clinical Research, Tumor Biology Center, 79106 Freiburg, Germany
| | - Holger Frey
- Institute
of Organic Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14, 55122 Mainz, Germany
| | - Mark Helm
- Institute
of Pharmacy and Biochemistry, Johannes Gutenberg-University Mainz, Staudingerweg
5, 55122 Mainz, Germany
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Thomas A, Müller SS, Frey H. Beyond Poly(ethylene glycol): Linear Polyglycerol as a Multifunctional Polyether for Biomedical and Pharmaceutical Applications. Biomacromolecules 2014; 15:1935-54. [DOI: 10.1021/bm5002608] [Citation(s) in RCA: 170] [Impact Index Per Article: 17.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Affiliation(s)
- Anja Thomas
- Institute
of Organic Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
| | - Sophie S. Müller
- Institute
of Organic Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
- Graduate School Materials Science in Mainz, Staudingerweg 9, 55128 Mainz, Germany
| | - Holger Frey
- Institute
of Organic Chemistry, Johannes Gutenberg-University Mainz, Duesbergweg 10-14, 55128 Mainz, Germany
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