151
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Semerak SN, Frank CW. Excimer fluorescence as a molecular probe of blend miscibility. 3. Effect of molecular weight of the host matrix. Macromolecules 2002. [DOI: 10.1021/ma50003a039] [Citation(s) in RCA: 35] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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152
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Char K, Frank CW, Gast AP, Tang WT. Hydrophobic attraction of pyrene-end-labeled poly(ethylene glycol) in water and water-methanol mixtures. Macromolecules 2002. [DOI: 10.1021/ma00174a023] [Citation(s) in RCA: 41] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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153
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Frank CW, Gashgari MA. Excimer Fluorescence as a Molecular Probe of Polymer Blend Compatibility. 1. Blends of Poly(2-vinylnaphthalene) with Poly(alkyl methacrylates). Macromolecules 2002. [DOI: 10.1021/ma60067a038] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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154
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Frederickson GH, Andersen HC, Frank CW. Electronic excited-state transport and trapping on polymer chains. Macromolecules 2002. [DOI: 10.1021/ma00131a010] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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155
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Hemker DJ, Garza V, Frank CW. Complexation of poly(acrylic acid) and poly(methacrylic acid) with pyrene-end-labeled poly(ethylene glycol): pH and fluorescence measurements. Macromolecules 2002. [DOI: 10.1021/ma00222a014] [Citation(s) in RCA: 50] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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156
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Fitzgibbon PD, Frank CW. Excimer formation in dilute solution. 1. Effect of pressure on 1,3-bis(2-naphthyl)propane and poly(2-vinylnaphthalene). Macromolecules 2002. [DOI: 10.1021/ma50007a009] [Citation(s) in RCA: 25] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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157
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Gelles R, Frank CW. Energy migration in the aromatic vinyl polymers. 2. Miscible blends of polystyrene with poly(vinyl methyl ether). Macromolecules 2002. [DOI: 10.1021/ma00231a012] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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158
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Fredrickson GH, Andersen HC, Frank CW. Electronic excitation transport as a probe of chain flexibility. Macromolecules 2002. [DOI: 10.1021/ma00138a013] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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159
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Gashgari MA, Frank CW. Excimer fluorescence as a molecular probe of polymer blend miscibility. 7. Nonequilibrium solvent casting effects in blends of poly(2-vinylnaphthalene) with poly(n-butyl methacrylate) and poly(methyl methacrylate). Macromolecules 2002. [DOI: 10.1021/ma00187a024] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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160
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Gelles R, Frank CW. Phase separation in polystyrene/poly(vinyl methyl ether) blends as studied by excimer fluorescence. Macromolecules 2002. [DOI: 10.1021/ma00234a007] [Citation(s) in RCA: 48] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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161
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Leezenberg PB, Frank CW. Selective Sorption and Solvation in Dansyl-Labeled Poly(dimethylsiloxane) Networks Swollen in Binary Solvent Mixtures. Macromolecules 2002. [DOI: 10.1021/ma00126a019] [Citation(s) in RCA: 15] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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162
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Oyama HT, Tang WT, Frank CW. Complex formation between poly(acrylic acid) and pyrene-labeled polyethylene glycol in aqueous solution. Macromolecules 2002. [DOI: 10.1021/ma00169a002] [Citation(s) in RCA: 74] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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163
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Frank CW. Observation of Relaxation Processes Near the Glass Transition by Means of Excimer Fluorescence. Macromolecules 2002. [DOI: 10.1021/ma60045a012] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
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164
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Torkelson JM, Tirrell M, Frank CW. Polystyrene-methylcyclohexane solutions undergoing phase separation: a study by fluorescence spectroscopy. Macromolecules 2002. [DOI: 10.1021/ma00138a015] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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165
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Viovy JL, Frank CW, Monnerie L. Fluorescence anisotropy decay studies of local polymer dynamics in the melt. 2. Labeled model compounds of variable chain length. Macromolecules 2002. [DOI: 10.1021/ma00154a042] [Citation(s) in RCA: 19] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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166
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Chen LT, Frank CW. Influence of the head-to-head defect and the molecular weight on the .alpha. .fwdarw. .gamma. solid-state transformation of poly(vinylidene fluoride). Macromolecules 2002. [DOI: 10.1021/ma00153a017] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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167
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Schönherr H, Paraschiv V, Zapotoczny S, Crego-Calama M, Timmerman P, Frank CW, Vancso GJ, Reinhoudt DN. Unraveling the nanostructure of supramolecular assemblies of hydrogen-bonded rosettes on graphite: an atomic force microscopy study. Proc Natl Acad Sci U S A 2002; 99:5024-7. [PMID: 11929980 PMCID: PMC122715 DOI: 10.1073/pnas.072685399] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The self-organization of multicomponent tetrarosette assemblies into ordered nanostructures on graphite surfaces has been studied by atomic force microscopy (AFM). Real-space information on the level of individual molecules allowed us to analyze the underlying structure in unprecedented detail. In highly ordered nanorod domains, tetrarosettes 1(3) x (DEB)(12) arrange in the form of parallel rows with a spacing of 4.6 +/- 0.1 nm. High resolution AFM revealed the internal packing of the tetrarosette assemblies in these rows, which can be described by an oblique lattice with a = 2.5 +/- 0.3 nm, b = 5.0 +/- 0.1 nm, and gamma = 122 +/- 3 degrees. The results, together with recent improvements in synthetic approaches, contribute to the development of a general strategy to develop H-bonding-based nanostructures with molecular precision.
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168
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Schönherr H, Wiyatno W, Pople J, Frank CW, Fuller GG, Gast AP, Waymouth RM. Morphology of Thermoplastic Elastomers: Elastomeric Polypropylene. Macromolecules 2002. [DOI: 10.1021/ma010959m] [Citation(s) in RCA: 57] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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169
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Naumann CA, Prucker O, Lehmann T, Rühe J, Knoll W, Frank CW. The polymer-supported phospholipid bilayer: tethering as a new approach to substrate-membrane stabilization. Biomacromolecules 2002; 3:27-35. [PMID: 11866552 DOI: 10.1021/bm0100211] [Citation(s) in RCA: 179] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
We present a new molecular engineering approach in which a polymer-supported phospholipid bilayer is vertically stabilized by controlled covalent tethering at both the polymer-substrate and polymer-bilayer interfaces. This approach is based on lipopolymer molecules, which not only form a polymer cushion between the phospholipid bilayer and a solid glass substrate but also act as covalent connections (tethers) between the bilayer and cushion. Our approach involves Langmuir-Blodgett transfer of a phospholipid-lipopolymer monolayer followed by Schaefer transfer of a pure phospholipid monolayer and is capable of varying the tethering density between the polymer layer and the phospholipid bilayer in a very controlled manner. Further stabilization is achieved if the glass substrate is surface-functionalized with a benzophenone silane. In this case, a photocross-linking reaction between the polymer and benzophenone group allows for the covalent attachment of the polymer cushion to the glass substrate. This approach is similar to that recently reported by Wagner and Tamm in which double tethering is achieved via lipopolymer silanes (Wagner, M. L.; Tamm, L. K. Biophys. J. 2000, 79, 1400). To obtain a deeper understanding of how the covalent tethering affects the lateral mobility of the bilayer, we performed fluorescence recovery after photobleaching (FRAP) experiments on polymer-tethered bilayers at different tethering densities (lipopolymer/phospholipid molar ratios). The FRAP data clearly indicate that the hydrophobic lipopolymer moieties act as rather immobile obstacles within the phospholipid bilayer, thereby leading to hindered diffusion of phospholipids. Whereas the high lateral diffusion coefficient of D = 17.7 mum(2)/s measured at low tethering density (5 mol % lipopolymer) indicates rather unrestricted motion within the bilayer, corresponding values at moderate (10 mol % lipopolymer) and high (30 mol % lipopolymer) tethering densities of D = 9.7 mum(2)/s and D = 1.1 mum(2)/s, respectively, show significant hindered diffusion. These results are contrary to the recent findings on similar membrane systems reported by Wagner and Tamm in which no significant change in phospholipid diffusion was found between 0 and 10 mol % lipopolymer. Our experimental report leads to a deeper understanding of the complex problem of interlayer coupling and offers a path toward a compromise between stability of the whole system and lateral mobility within the bilayer. Furthermore, the FRAP measurements show that polymer-tethered membranes are very interesting model systems for studying problems of restricted diffusion within two-dimensional fluids.
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170
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Würsch A, Möller M, Glauser T, Lim LS, Voytek SB, Hedrick JL, Frank CW, Hilborn JG. Dendritic−Linear AxBx Block Copolymers Prepared via Controlled Ring-Opening Polymerization of Lactones from Orthogonally Protected Multifunctional Initiators. Macromolecules 2001. [DOI: 10.1021/ma0105035] [Citation(s) in RCA: 38] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/17/2022]
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171
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Heise A, Diamanti S, Hedrick JL, Frank CW, Miller RD. Investigation of the Initiation Behavior of a Dendritic 12-Arm Initiator in Atom Transfer Radical Polymerization. Macromolecules 2001. [DOI: 10.1021/ma001508p] [Citation(s) in RCA: 58] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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172
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Heise A, Trollsås M, Magbitang T, Hedrick JL, Frank CW, Miller RD. Star Polymers with Alternating Arms from Miktofunctional μ-Initiators Using Consecutive Atom Transfer Radical Polymerization and Ring-Opening Polymerization. Macromolecules 2001. [DOI: 10.1021/ma0012954] [Citation(s) in RCA: 110] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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173
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Knoll W, Frank CW, Heibel C, Naumann R, Offenhäusser A, Rühe J, Schmidt EK, Shen WW, Sinner A. Functional tethered lipid bilayers. J Biotechnol 2000; 74:137-58. [PMID: 11143794 DOI: 10.1016/s1389-0352(00)00012-x] [Citation(s) in RCA: 148] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Our strategy to provide the structural basis for the build-up of functional tethered membranes focuses on three approaches: the first one is based on the pre-organization of a monomolecular layer of a lipopolymer at the water/air interface which is then transferred to a solid support. Prior to deposition, the substrate is coated with a layer of benzophenone-derivatized silane molecules that allow for a stable covalent attachment by photo-cross-linking of some of the monomer units of the lipopolymer to the support. An alternative concept realizes a layer-by-layer deposition of the various structural elements: (1) the attachment layer with the reactive sites for the chemical stabilization; (2) a polymer 'cushion' prepared by adsorption and simultaneous or subsequent partial covalent binding to the reactive sites; and (3) a lipid monolayer transferred from the water/air interface, that contains a certain amount of lipids with reactive headgroups which, upon binding to the polymer tether, act as anchor lipids stabilizing the whole monolayer/cushion-composite. And finally, we build peptide-supported monolayers by first (self-) assembling amino acid sequences of various lengths via a SH-group near their N-terminus onto Au substances and use then their COO(-)-terminus to chemically attach phosphatidyl-ethanolamine lipids to form a stable monolayer of lipid-peptide conjugates. All the individual preparation steps and the various resulting (multi-) layers are characterized by surface plasmon spectroscopy, X-ray and neutron-reflectometry, contact angle measurements, IR spectroscopy, fluorescence microscopy, scanning probe microscopies, as well as, electrochemical techniques. For all tethering systems, the final membranes' architecture is obtained by fusing lipid vesicles onto the lipid monolayer. Proteins can be incorporated by either fusing vesicles that are loaded with the respective receptors, pores, or ion pumps via a reconstitution procedure, or via a transfer directly from a micellar solution to the pre-formed lipid bilayer at the solid support by a dialysis step. Two structural/dynamical features of tethered membranes which are considered to be of particular functional relevance, i.e. the degree of water uptake and, hence, the degree of swelling of the polymer support, as well as the lateral mobility of the lipid molecules in the membrane, are tested by surface plasmon optics and by measurements of the fluorescence recovery after photobleaching (FRAP), respectively. The results confirm that the presented preparation protocols yield fluid bilayers that mimic certain relevant properties of biological membranes. The functional characterization of tethered membranes, which is briefly summarized, is based on various electrochemical techniques, in particular, impedance spectroscopy, cyclic voltammetry, and chronoamperometric studies. The results obtained for reconstituted H(+)-ATPase from chloroplasts and E. coli and for cytochrome oxidase (with and without cytochrome c) confirm the incorporation of the proteins in an active form, thus, opening opportunities for novel sensor formats or offering a completely new model membrane system.
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174
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Heise A, Nguyen C, Malek R, Hedrick JL, Frank CW, Miller RD. Starlike Polymeric Architectures by Atom Transfer Radical Polymerization: Templates for the Production of Low Dielectric Constant Thin Films. Macromolecules 2000. [DOI: 10.1021/ma991091r] [Citation(s) in RCA: 106] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
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175
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Chang YC, Frank CW, Forstmann GG, Johannsmann D. Quadrupolar and polar anisotropy in end-grafted α-helical poly(γ-benzyl-L-glutamate) on solid substrates. J Chem Phys 1999. [DOI: 10.1063/1.479909] [Citation(s) in RCA: 26] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
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