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Hassler JF, Lawson M, Arroyo EC, Bates FS, Hackel BJ, Lodge TP. Discovery of Kinetic Trapping of Poloxamers inside Liposomes via Thermal Treatment. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2023; 39:14263-14274. [PMID: 37755825 PMCID: PMC10853007 DOI: 10.1021/acs.langmuir.3c01499] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/28/2023]
Abstract
Poloxamers, a class of biocompatible, commercially available amphiphilic block polymers (ABPs) comprising poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO) blocks, interact with phospholipid bilayers, resulting in altered mechanical and surface properties. These block copolymers are useful in a variety of applications including therapeutics for Duchenne muscular dystrophy, as cell membrane stabilizers, and for drug delivery, as liposome surface modifying agents. Hydrogen bonding between water and oxygen atoms in PEO and PPO units results in thermoresponsive behavior because the bound water shell around both blocks dehydrates as the temperature increases. This motivated an investigation of poloxamer-lipid bilayer interactions as a function of temperature and thermal history. In this study, we applied pulsed-field-gradient NMR spectroscopy to measure the fraction of chains bound to 1-palmitoyl-2-oleoyl-glycero-3-phosphocholine (POPC) liposomes between 10 and 50 °C. We measured an (11 ± 3)-fold increase in binding affinity at 37 °C relative to 27 °C. Moreover, following incubation at 37 °C, it takes weeks for the system to re-equilibrate at 25 °C. Such slow desorption kinetics suggests that at elevated temperatures polymer chains can pass through the bilayer and access the interior of the liposomes, a mechanism that is inaccessible at lower temperatures. We propose a molecular mechanism to explain this effect, which could have important ramifications on the cellular distribution of ABPs and could be exploited to modulate the mechanical and surface properties of liposomes and cell membranes.
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Nagao M, Seto H. Neutron scattering studies on dynamics of lipid membranes. BIOPHYSICS REVIEWS 2023; 4:021306. [PMID: 38504928 PMCID: PMC10903442 DOI: 10.1063/5.0144544] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 01/30/2023] [Accepted: 05/01/2023] [Indexed: 03/21/2024]
Abstract
Neutron scattering methods are powerful tools for the study of the structure and dynamics of lipid bilayers in length scales from sub Å to tens to hundreds nm and the time scales from sub ps to μs. These techniques also are nondestructive and, perhaps most importantly, require no additives to label samples. Because the neutron scattering intensities are very different for hydrogen- and deuterium-containing molecules, one can replace the hydrogen atoms in a molecule with deuterium to prepare on demand neutron scattering contrast without significantly altering the physical properties of the samples. Moreover, recent advances in neutron scattering techniques, membrane dynamics theories, analysis tools, and sample preparation technologies allow researchers to study various aspects of lipid bilayer dynamics. In this review, we focus on the dynamics of individual lipids and collective membrane dynamics as well as the dynamics of hydration water.
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Affiliation(s)
| | - Hideki Seto
- Institute of Materials Structure Science, High Energy Accelerator Research Organization, Tsukuba, Ibaraki 305-0801, Japan
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Hassler JF, Crabtree A, Liberman L, Bates FS, Hackel BJ, Lodge TP. Effect of Bottlebrush Poloxamer Architecture on Binding to Liposomes. Biomacromolecules 2023; 24:449-461. [PMID: 36563027 DOI: 10.1021/acs.biomac.2c01274] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022]
Abstract
Poloxamers─triblock copolymers consisting of poly(ethylene oxide) (PEO) and poly(propylene oxide) (PPO)─have demonstrated cell membrane stabilization efficacy against numerous types of stress. However, the mechanism responsible for this stabilizing effect remains elusive, hindering engineering of more effective therapeutics. Bottlebrush polymers have a wide parameter space and known relationships between architectural parameters and polymer properties, enabling their use as a tool for mechanistic investigations of polymer-lipid bilayer interactions. In this work, we utilized a versatile synthetic platform to create novel bottlebrush analogues to poloxamers and then employed pulsed-field-gradient NMR and an in vitro osmotic stress assay to explore the effect of bottlebrush architectural parameters on binding to, and protection of, model phospholipid bilayers. We found that the binding affinity of a bottlebrush poloxamer (BBP) (B-E1043P515, Mn ≈ 26 kDa) is about 3 times higher than a linear poloxamer with a similar composition and number of PPO units (L-E93P54E93, Mn ≈ 11 kDa). Furthermore, BBP binding is sensitive to overall molecular weight, side-chain length, and architecture (statistical versus block). Finally, all tested BBPs exhibit a protective effect on cell membranes under stress at sub-μM concentrations. As the factors controlling membrane affinity and protection efficacy of bottlebrush poloxamers are not understood, these results provide important insight into how they adhere to and stabilize a lipid bilayer surface.
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Crabtree AA, Bates FS, Hackel BJ. Concentration Threshold for Membrane Protection by PEO-PPO Block Copolymers with Variable Molecular Architectures. ACS APPLIED POLYMER MATERIALS 2022; 4:3259-3269. [PMID: 36777189 PMCID: PMC9907980 DOI: 10.1021/acsapm.1c01807] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/15/2023]
Abstract
Poloxamer 188, a poly(ethylene oxide)-b-poly(propylene oxide)-b-poly(ethylene oxide) (PEO-PPO-PEO) triblock copolymer, protects cell membranes in several injury models. However, the nature of the copolymer/membrane interaction and the mechanism of membrane protection remain unknown. Systematic variations of the block copolymer architecture - including PPO-PEO-PPO triblocks and PPO-PEO diblocks - were used to probe the mechanism and evaluate the potential for alternative architectures to yield superior protection. To test the polymers, murine myoblasts were subjected to an osmotic stress, and membrane integrity was quantified by measuring lactate dehydrogenase (LDH) leakage. These experiments exposed a concentration threshold effect where all tested polymers reach 50% leakage of LDH compared to a non-treated buffer only control over a narrow concentration range of 0.8-4 μM. Differences in polymer protection at lower concentrations indicate that protection increases with the PPO-PEO-PPO molecular architecture and increasing hydrophobicity.
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Affiliation(s)
| | | | - Benjamin J. Hackel
- Corresponding Author: Benjamin J. Hackel – Department of Chemical Engineering and Materials Science, University of Minnesota, Minneapolis, MN 55455, Phone: 612-624-7102,
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Hassler JF, Van Zee NJ, Crabtree AA, Bates FS, Hackel BJ, Lodge TP. Synthesis and Micellization of Bottlebrush Poloxamers. ACS Macro Lett 2022; 11:460-467. [PMID: 35575325 PMCID: PMC9726453 DOI: 10.1021/acsmacrolett.2c00053] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
Bottlebrush polymers are characterized by an expansive parameter space, including graft length and spacing along the backbone, and these features impact various structural and physical properties such as molecular diffusion and bulk viscosity. In this work, we report a synthetic strategy for making grafted block polymers with poly(propylene oxide) and poly(ethylene oxide) side chains, bottlebrush analogues of poloxamers. Combined anionic and sequential ring-opening metathesis polymerization yielded low dispersity polymers, at full conversion of the macromonomers, with control over graft length, graft end-groups, and overall molecular weight. A set of bottlebrush poloxamers (BBPs), with identical graft lengths and composition, was synthesized over a range of molecular weights. Dynamic light scattering and transmission electron microscopy were used to characterize micelle formation in aqueous buffer. The critical micelle concentration scales exponentially with overall molecular weight for both linear and bottlebrush poloxamers; however, the bottlebrush architecture shifts micelle formation to a much higher concentration at a comparable molecular weight. Consequently, BBPs can exist in solution as unimers at significantly higher molecular weights and concentrations than the linear analogues.
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Grigoreva A, Tarankova K, Zamyshlyayeva O, Zaitsev S. Aggregation behaviour of poly(fluoro(meth)acrylate)-block-poly(acrylic acid) copolymers at the air /water interface. JOURNAL OF POLYMER RESEARCH 2021. [DOI: 10.1007/s10965-021-02629-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/21/2022]
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Yang Z, Zhao J, Emrick T. Functional Polymer Zwitterions as Reactive Surfactants for Nanoparticle Capture. ACS APPLIED MATERIALS & INTERFACES 2021; 13:21898-21904. [PMID: 33942613 DOI: 10.1021/acsami.1c05955] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
We describe the synthesis of sulfothetin (ST)-containing polymer zwitterions and their use as polymer surfactants for stabilizing emulsion droplets and for capturing and transporting nanoparticles (NPs) through a flowing aqueous fluid. In contrast to conventional zwitterions, which are chemically inert, the multifunctional ST-containing copolymers we describe both participate in droplet stabilization and embed reactive functionality directly into the zwitterionic framework. Advantageously including these ST zwitterions in phosphorylcholine (PC)-containing copolymers proved particularly useful for producing surfactants that contributed characteristics of droplet stabilization and interfacial reactivity. This was demonstrated by NP pickup, or "capture", experiments that were performed by circulating ST-coated emulsion droplets across a substrate, in a flow cell, containing amine-functionalized silica NPs. The resultant NP adherence to the fluid-fluid interface of the droplets hinged on the available reactivity of both the electrophilic (from ST) and nucleophilic (from the NPs) components as well as the solution pH and extent of amine functionality on the NPs.
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Affiliation(s)
- Zhefei Yang
- Polymer Science & Engineering Department Conte Center for Polymer Research, University of Massachusetts, 120 Governors Drive, Amherst 01003, Massachusetts, United States
| | - Jing Zhao
- Polymer Science & Engineering Department Conte Center for Polymer Research, University of Massachusetts, 120 Governors Drive, Amherst 01003, Massachusetts, United States
| | - Todd Emrick
- Polymer Science & Engineering Department Conte Center for Polymer Research, University of Massachusetts, 120 Governors Drive, Amherst 01003, Massachusetts, United States
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De Mel JU, Gupta S, Willner L, Allgaier J, Stingaciu LR, Bleuel M, Schneider GJ. Manipulating Phospholipid Vesicles at the Nanoscale: A Transformation from Unilamellar to Multilamellar by an n-Alkyl-poly(ethylene oxide). LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2021; 37:2362-2375. [PMID: 33570419 PMCID: PMC8023706 DOI: 10.1021/acs.langmuir.0c03302] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/17/2020] [Revised: 01/27/2021] [Indexed: 05/05/2023]
Abstract
We investigated the influence of an n-alkyl-PEO polymer on the structure and dynamics of phospholipid vesicles. Multilayer formation and about a 9% increase in the size in vesicles were observed by cryogenic transmission electron microscopy (cryo-TEM), dynamic light scattering (DLS), and small-angle neutron/X-ray scattering (SANS/SAXS). The results indicate a change in the lamellar structure of the vesicles by a partial disruption caused by polymer chains, which seems to correlate with about a 30% reduction in bending rigidity per unit bilayer, as revealed by neutron spin echo (NSE) spectroscopy. Also, a strong change in lipid tail relaxation was observed. Our results point to opportunities using synthetic polymers to control the structure and dynamics of membranes, with possible applications in technical materials and also in drug and nutraceutical delivery.
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Affiliation(s)
- Judith U. De Mel
- Department
of Chemistry and Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Sudipta Gupta
- Department
of Chemistry and Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
| | - Lutz Willner
- Jülich
Center for Neutron Science (JCNS-1) and Institute of Biological Information
Processing (IBI-8) Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Jürgen Allgaier
- Jülich
Center for Neutron Science (JCNS-1) and Institute of Biological Information
Processing (IBI-8) Forschungszentrum Jülich GmbH, 52428 Jülich, Germany
| | - Laura R. Stingaciu
- Neutron
Sciences Directorate, Oak Ridge National
Laboratory (ORNL), POB 2008, 1 Bethel Valley Road, Oak Ridge, Tennessee 37831, United States
| | - Markus Bleuel
- NIST
Center for Neutron Research, National Institute
of Standards and Technology, Gaithersburg, Maryland 20899-8562, United States
| | - Gerald J. Schneider
- Department
of Chemistry and Department of Physics & Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803, United States
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Qian S, Sharma VK, Clifton LA. Understanding the Structure and Dynamics of Complex Biomembrane Interactions by Neutron Scattering Techniques. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:15189-15211. [PMID: 33300335 DOI: 10.1021/acs.langmuir.0c02516] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
The membrane is one of the key structural materials of biology at the cellular level. Composed predominantly of a bilayer of lipids with embedded and bound proteins, it defines the boundaries of the cell and many organelles essential to life and therefore is involved in almost all biological processes. Membrane-specific interactions, such as drug binding to a membrane receptor or the interactions of an antimicrobial compound with the lipid matrix of a pathogen membrane, are of interest across the scientific disciplines. Herein we present a review, aimed at nonexperts, of the major neutron scattering techniques used in membrane studies: small-angle neutron scattering, neutron membrane diffraction, neutron reflectometry, quasielastic neutron scattering, and neutron spin echo. Neutron scattering techniques are well suited to studying biological membranes. The nondestructive nature of cold neutrons means that samples can be measured for long periods without fear of beam damage from ultraviolet, electron, or X-ray radiation, and neutron beams are highly penetrating, thus offering flexibility in samples and sample environments. Most important is the strong difference in neutron scattering lengths between the two most abundant forms of hydrogen, protium and deuterium. Changing the relative amounts of protium/deuterium in a sample allows the production of a series of neutron scattering data sets, enabling the observation of differing components within complex membrane architectures. This approach can be as simple as using the naturally occurring neutron contrast between different biomolecules to study components in a complex by changing the solution H2O/D2O ratio or as complex as selectively labeling individual components with hydrogen isotopes. This review presents an overview of each experimental technique with the neutron instrument configuration, related sample preparation and sample environment, and data analysis, highlighted by a special emphasis on using prominent neutron contrast to understand structure and dynamics. This review gives researchers a practical introduction to the often enigmatic suite of neutron beamlines, thereby lowering the barrier to taking advantage of these large-facility techniques to achieve new understandings of membranes and their interactions with other molecules.
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Affiliation(s)
- Shuo Qian
- Neutron Scattering Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37830, United States
| | - Veerendra Kumar Sharma
- Solid State Physics Division, Bhabha Atomic Research Centre, Mumbai 400085, India
- Homi Bhabha National Institute, Anushaktinagar, Mumbai 400094, India
| | - Luke A Clifton
- ISIS Neutron and Muon Source, Rutherford Appleton Laboratory, Harwell Campus, Didcot, Oxfordshire, U.K. OX11 0QX
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Zeng T, Gautam RP, Barile CJ, Li Y, Tse ECM. Nitrile-Facilitated Proton Transfer for Enhanced Oxygen Reduction by Hybrid Electrocatalysts. ACS Catal 2020. [DOI: 10.1021/acscatal.0c03506] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/08/2023]
Affiliation(s)
- Tian Zeng
- Department of Chemistry, CAS-HKU Joint Laboratory of Metallomics on Health and Environment, University of Hong Kong, Hong Kong SAR 999077, China
| | - Rajendra P. Gautam
- Department of Chemistry, University of Nevada, Reno, Nevada 89557, United States
| | | | - Ying Li
- Department of Chemistry, CAS-HKU Joint Laboratory of Metallomics on Health and Environment, University of Hong Kong, Hong Kong SAR 999077, China
- HKU Shenzhen Institute of Research and Innovation, Shenzhen 518057, China
| | - Edmund C. M. Tse
- Department of Chemistry, CAS-HKU Joint Laboratory of Metallomics on Health and Environment, University of Hong Kong, Hong Kong SAR 999077, China
- HKU Zhejiang Institute of Research and Innovation, Zhejiang 311305, China
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Yu J, Mao J, Nagao M, Bu W, Lin B, Hong K, Jiang Z, Liu Y, Qian S, Tirrell M, Chen W. Structure and dynamics of lipid membranes interacting with antivirulence end-phosphorylated polyethylene glycol block copolymers. SOFT MATTER 2020; 16:983-989. [PMID: 31851201 DOI: 10.1039/c9sm01642b] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
The structure and dynamics of lipid membranes in the presence of extracellular macromolecules are critical for cell membrane functions and many pharmaceutical applications. The pathogen virulence-suppressing end-phosphorylated polyethylene glycol (PEG) triblock copolymer (Pi-ABAPEG) markedly changes the interactions with lipid vesicle membranes and prevents PEG-induced vesicle phase separation in contrast to the unphosphorylated copolymer (ABAPEG). Pi-ABAPEG weakly absorbs on the surface of lipid vesicle membranes and slightly changes the structure of 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) unilamellar vesicles at 37 °C, as evidenced by small angle neutron scattering. X-ray reflectivity measurements confirm the weak adsorption of Pi-ABAPEG on DMPC monolayer, resulting in a more compact DMPC monolayer structure. Neutron spin-echo results show that the adsorption of Pi-ABAPEG on DMPC vesicle membranes increases the membrane bending modulus κ.
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Affiliation(s)
- Jing Yu
- Centre for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA. and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
| | - Jun Mao
- Centre for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA. and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
| | - Michihiro Nagao
- NIST Centre for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102, USA and Centre for Exploration of Energy and Matter, Indiana University, Bloomington, IN 47408, USA
| | - Wei Bu
- Centre for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637, USA
| | - Binhua Lin
- Centre for Advanced Radiation Sources, University of Chicago, Chicago, IL 60637, USA and James Franck Institute, University of Chicago, Chicago, IL 60637, USA
| | - Kunlun Hong
- Centre for Nanophase Materials Sciences, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Zhang Jiang
- Advanced Photon Source, Argonne National Laboratory, Lemont, IL 60439, USA
| | - Yun Liu
- NIST Centre for Neutron Research, National Institute of Standards and Technology, Gaithersburg, MD 20899-6102, USA and Department of Chemical and Biomolecular Engineering, Centre for Neutron Science, University of Delaware, Newark, DE 19716, USA
| | - Shuo Qian
- Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, TN 37831, USA
| | - Matthew Tirrell
- Centre for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA. and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
| | - Wei Chen
- Centre for Molecular Engineering and Materials Science Division, Argonne National Laboratory, Lemont, IL 60439, USA. and Pritzker School of Molecular Engineering, University of Chicago, Chicago, IL 60637, USA.
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