Cross-Linking Polymerization in Two-Dimensional Assemblies:  Effect of the Reactive Group Site

Liu, Sanchao; O’Brien, David F.

doi:10.1021/ma990528s

Cited by 43 publications

(53 citation statements)

References 27 publications

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“…Although cross-linked PSLBs are formed by both methods, previous studies on poly(bis-SorbPC) vesicles have shown that redox initiation produces a greater degree of polymerization (X n = 50-500) than UV irradiation (X n = 3-10). [32][33][34] A similar trend likely occurs in bis-SorbPC PSLBs polymerized by these two methods, and significant differences in their respective structural properties have been observed. 14,15 The origin of these differences may be different propagation mechanisms for the two methods.…”

Section: Xps Of Uv-and Redox-polymerized Bis-sorbpc Bilayerssupporting

confidence: 52%

Ultra-High Vacuum Surface Analysis Study of Rhodopsin Incorporation into Supported Lipid Bilayers

et al. 2008

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Planar supported lipid bilayers that are stable under ambient atmospheric and ultra-high-vacuum conditions were prepared by cross-linking polymerization of bis-sorbylphosphatidylcholine (bisSorbPC). X-ray photoelectron spectroscopy (XPS) and time-of-flight secondary ion mass spectrometry (ToF-SIMS) were employed to investigate bilayers that were cross-linked using either redox-initiated radical polymerization or ultraviolet photopolymerization. The redox method yields a more structurally intact bilayer; however, the UV method is more compatible with incorporation of transmembrane proteins. UV polymerization was therefore used to prepare cross-linked bilayers with incorporated bovine rhodopsin, a light-activated, G-protein-coupled receptor (GPCR). A previous study (Subramaniam, V.; Alves, I. D.; Salgado, G. F. J.; Lau, P. W.; Wysocki, R. J.; Salamon, Z.; Tollin, G.; Hruby, V. J.; Brown, M. F.; Saavedra, S. S. J. Am. Chem. Soc. 2005, 127, 5320-5321) showed that rhodopsin retains photoactivity after incorporation into UV-polymerized bis-SorbPC, but did not address how the protein is associated with the bilayer. In this study, we show that rhodopsin is retained in supported bilayers of poly(bis-SorbPC) under ultra-high-vacuum conditions, on the basis of the increase in the XPS nitrogen concentration and the presence of characteristic amino acid peaks in the ToF-SIMS data. Angle-resolved XPS data show that the protein is inserted into the bilayer, rather than adsorbed on the bilayer surface. This is the first study to demonstrate the use of ultra-high-vacuum techniques for structural studies of supported proteolipid bilayers.

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Section: Xps Of Uv-and Redox-polymerized Bis-sorbpc Bilayerssupporting

confidence: 52%

Ultra-High Vacuum Surface Analysis Study of Rhodopsin Incorporation into Supported Lipid Bilayers

et al. 2008

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“…Previous studies demonstrated that cross-linked lipid vesicles were stable in the presence of excess surfactant, whereas unpolymerized or linearly polymerized vesicles were dissolved by surfactant. 7,21 Further studies also showed that the surfactant solubilization was dependent on the degree of polymerization, extent of cross-linking, and location of the reactive groups in the lipid. Vesicles composed of oligomers were efficiently dissolved with TX-100, while vesicles composed of longer linear polymeric lipids were less readily solubilized.…”

Section: Resultsmentioning

confidence: 99%

Synthesis and Polymerization of Heterobifunctional Amphiphiles to Cross-Link Supramolecular Assemblies

2000

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The cross-linking of supramolecular assemblies of hydrated amphiphiles is an effective method to stabilize the assembly. A well-known strategy for cross-linking of lipids in lyotropic phases is the inclusion of identical reactive groups in each hydrophobic tail of the lipids. An alternative approach is to incorporate two similar but distinct groups into different locations within a single hydrophobic tail of the amphiphile. In principle, these heterobifunctional amphiphiles could react to form ladderlike polymers or cross-linked polymers. This report describes the synthesis, characterization, and polymerization in lipid vesicles of two series of heterobifunctional phosphatidylcholine (PC) lipids with different separation distances between the two reactive groups. One of the groups, i.e., dienoyl (Den), is attached to the secondary oxygen of the glycerol backbone of the lipid, and the other is either an acryloyl (Acryl) or sorbyl (Sorb) functional group located at the sn-2 chain terminus. Polymerization of both reactive groups in the Acryl/DenPC or the Sorb/DenPC was achieved by either redox polymerization or direct photoirradiation. The degree of polymerization depends on the initiation chemistry. Photoirradiation yields oligomers that are insufficient to cross-link the vesicles, whereas redox-initiated radical polymerization affords cross-linked polymeric vesicles. Under radical polymerization conditions a spacer length of seven or more atoms between the two reactive groups was long enough to ensure that each reactive group can follow an independent reaction path.

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“…Monomer 2c can form a Q II phase without co-monomers and is intrinsically cross-linkable, but the doubly-reactive single tail is synthetically complex to produce. 25 These papers, as well as other papers by O'Brien and co-workers on these polymerizable Q II -phase systems, [28][29][30][31] focused mostly on fundamental studies of chainaddition polymerization in Q phases. They also studied the diffusion of dendrimers in the water channels of the cross-linked Q II -phase mixed-lipid systems and found that it was sufficiently rapid for the materials to be potentially useful for controlled release applications of encapsulated large drugs and macromolecules.…”

Section: Nanoporous Polymer Materials Via the Direct Polymerization Omentioning

confidence: 99%

Nanoporous polymer materials based on self-organized, bicontinuous cubic lyotropic liquid crystal assemblies and their applications

Wiesenauer

Gin

2012

Polym J

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The bicontinuous cubic (Q) lyotropic liquid crystal (LLC) phases formed by the phase-separation and self-organization of amphiphilic molecules in water are intriguing structures for a number of transport-related applications because they possess ordered, uniform, 3D-interconnected water channels on the size of single molecules. Polymeric materials formed from either the templated polymerization or cross-linking of conventional monomers around Q phases, or the direct polymerization or cross-linking of Q phases formed by reactive amphiphiles retain the desired LLC nanostructure but are more robust for true application development. The structures of Q LLC phases were only elucidated in the late 1980s, and the first successful preparation of polymers based on Q phases was reported soon after. However, the development and demonstration of these nanoporous polymers for material applications were not realized until the first decade of the twenty-first century. This focus review provides an overview of work in the area of Q LLC phase-based polymer materials, with a focus on the work of our research group and that of our collaborators on polymer networks prepared by the direct polymerization of reactive Q phases and their development as functional materials for several engineering applications. Keywords: bicontinuous cubic; liquid crystal; lyotropic; nanoporous; polymer INTRODUCTION Lyotropic liquid crystals (LLCs) are amphiphilic molecules typically composed of a hydrophilic headgroup section and a hydrophobic tail section that have the ability to phase-separate and self-organize into nanostructured assemblies in the presence of water. The resulting fluid, ordered LLC phases have varying degrees of average order, different levels of hydrophilic and hydrophobic domain interconnectivity, and uniform periodic features in the circa 1-10 nm size range (For general reviews on LLC phases and their classifications, see: refs 1-3). LLC phases have recently attracted a great deal of attention because of their benefits as a versatile platform for the design of functional, nanoporous polymer materials. For example, by employing reactive LLCs (that is, monomers), the desired phase can be locked-in directly via chemical cross-linking to afford robust, nanoporous polymer networks (For reviews on the synthesis and applications of nanostructured polymers made from polymerizable LLCs, see: refs 4-6). LLC networks made by this approach have been used for applications such as templated nanocomposite synthesis, drug delivery, molecular transport/separation and heterogeneous catalysis. 7,8 Alternatively, non-polymerizable LLC phases have been used as nanostructured templates for the polymerization of conventional monomers dissolved in either the hydrophilic or hydrophobic domains. Subsequent

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Cross-Linking Polymerization in Two-Dimensional Assemblies: Effect of the Reactive Group Site

Cited by 43 publications

References 27 publications

Ultra-High Vacuum Surface Analysis Study of Rhodopsin Incorporation into Supported Lipid Bilayers

Ultra-High Vacuum Surface Analysis Study of Rhodopsin Incorporation into Supported Lipid Bilayers

Synthesis and Polymerization of Heterobifunctional Amphiphiles to Cross-Link Supramolecular Assemblies

Nanoporous polymer materials based on self-organized, bicontinuous cubic lyotropic liquid crystal assemblies and their applications

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