The different faces of poly(ethylene glycol)

Israelachvili, Jacob N.

doi:10.1073/pnas.94.16.8378

Cited by 279 publications

(217 citation statements)

References 10 publications

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“…Thus, we can conclude that this rough estimation is consistent with the experimental results. Budding transformation was more frequent with PEG than with dextran at an identical molecular weight and concentration because PEG has a greater osmotic activity (22,51), resulting in a more substantial depletion interaction. Qualitatively, we can extend this discussion for transformations from multivesicular, torus, and horseshoe shapes (Fig.…”

Section: Resultsmentioning

confidence: 99%

Coupling of the fusion and budding of giant phospholipid vesicles containing macromolecules

Terasawa

Nishimura

Suzuki

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

160

166

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Mechanisms that enabled primitive cell membranes to self-reproduce have been discussed based on the physicochemical properties of fatty acids; however, there must be a transition to modern cell membranes composed of phospholipids [Budin I, Szostak JW (2011) Proc Natl Acad Sci USA 108:5249–5254]. Thus, a growth-division mechanism of membranes that does not depend on the chemical nature of amphiphilic molecules must have existed. Here, we show that giant unilamellar vesicles composed of phospholipids can undergo the coupled process of fusion and budding transformation, which mimics cell growth and division. After gaining excess membrane by electrofusion, giant vesicles spontaneously transform into the budded shape only when they contain macromolecules (polymers) inside their aqueous core. This process is a result of the vesicle maximizing the translational entropy of the encapsulated polymers (depletion volume effect). Because the cell is a lipid membrane bag containing highly concentrated biopolymers, this coupling process that is induced by physical and nonspecific interactions may have a general importance in the self-reproduction of the early cellular compartments.

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Section: Resultsmentioning

confidence: 99%

Coupling of the fusion and budding of giant phospholipid vesicles containing macromolecules

Terasawa

Nishimura

Suzuki

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

160

166

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“…The properties of polyethylene glycol make it unique among other watersoluble polymers. 30,31 A small Flory-Huggins parameter and close-to-unity intramolecular expansion factor characterize the interactions of PEG with water. 54 The amphipathic composition of this polyether, containing hydrophobic ethylene units (-CH 2 -CH 2 -) and hydrogen-bond-accepting ether oxygens (-O-), appears to dictate its behavior and conformation in aqueous media.…”

Section: Considerations In the Strategy For Surface Derivatizationmentioning

confidence: 99%

“…22,31,64 It is believed that the hydration of the PEG chains dictates its nonfouling characteristics. In aqueous media, PEG assumes helical conformation, in which the distance between neighboring ether oxygens,~0.29 nm, is similar to the average separation between the oxygens in liquid water.…”

Section: Introductionmentioning

confidence: 99%

Surface-Bound Proteins with Preserved Functionality

et al. 2009

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Abstract-Biocompatibility of materials strongly depends on their surface properties. Therefore, surface derivatization in a controllable manner provides means for achieving interfaces essential for a broad range of chemical, biological, and medical applications. Bioactive interfaces, while manifesting the activity for which they are designed, should suppress all nonspecific interaction between the supporting substrates and the surrounding media. This article describes a procedure for chemical derivatization of glass and silicon surfaces with polyethylene glycol (PEG) layers covalently functionalized with proteins. While the proteins introduce the functionality to the surfaces, the PEGs provide resistance against nonspecific interactions. For formation of aldehyde-functionalized surfaces, we coated the substrates with acetals (i.e., protected aldehydes). To avoid deterioration of the surfaces, we did not use strong mineral acids for the deprotection of the aldehydes. Instead, we used a relatively weak Lewis acid for conversion of the acetals into aldehydes. Introduction of a,x-bifunctional polymers into the PEG layers, bound to the aldehydes, allowed us to covalently attach green fluorescent protein and bovine carbonic anhydrase to the surfaces. Spectroscopic studies indicated that the surface-bound proteins preserve their functionalities. The surface concentrations of the proteins, however, did not manifest linear proportionality to the molar fractions of the bifunctional PEGs used for the coatings. This finding suggests that surface-loading ratios cannot be directly predicted from the compositions of the solutions of competing reagents used for chemical derivatization.

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“…Long chain podands are also used as agents for improving bio-compatibility in immunological applications [32][33][34] and as ion channel models [35]. Improved knowledge of the structures formed when long chain podands coordinate with alkali metal ions, and particularly with the ubiquitous Na ϩ and K ϩ , can be of use in improving the applications of these materials.…”

mentioning

confidence: 99%

Poly(ethylene glycol) doubly and singly cationized by different alkali metal ions: Relative cation affinities and cation-dependent resolution in a quadrupole ion trap mass spectrometer

Bogan

Agnes

2002

J. Am. Soc. Mass Spectrom.

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Structural information of gas phase complexes of poly(ethylene glycol) (PEG) cationized by one or two different alkali metal ions is inferred from MS and MS/MS experiments performed with an electrospray quadrupole ion trap mass spectrometer. The rationale for selecting PEG was that its sites for cation binding are non-selective with respect to the repeating monomeric unit of the polymer, but there is selectivity with respect to the formation of an inner coordination sphere specific to each metal ion. The dissociation of [M 1 ϩ M 2 ϩ (EO23)], where EO23 ϭ linear polymer of ethylene oxide, 23 units in length, resulted in loss of one of the alkali metal ions, with preference for loss of the larger cation, with no fragmentation of the PEG backbone for Na, K, Rb, and Cs. Li was not examined in this portion of the study. The selectivity for loss of the larger alkali metal ion was [Na -20]. Factors involved in the solution phase molecular recognition are solvation enthalpy and entropy for both species and the number of atoms from the ligand that are involved with the binding of the metal ion, plus any conformational change of the ligand between its unbound and bound forms [21]. The intrinsic properties of the ion-dipole bonds in these non-covalent complexes are being deduced using a variety of gas phase techniques, including the equilibrium method [22], threshold CID [23][24][25][26], and ion chromatography [27,28].The long chain podands have received comparatively less attention by mass spectrometry [29,30], yet their industrial usage is immense, ranging from the fabrication of materials with varied properties to their use as phase transfer catalysts in industrial processes [31]. Long chain podands are also used as agents for improving bio-compatibility in immunological applications [32][33][34] and as ion channel models [35]. Improved knowledge of the structures formed when long chain podands coordinate with alkali metal ions, and particularly with the ubiquitous Na ϩ and K ϩ , can be of use in improving the applications of these materials.Here we report the uni-molecular dissociation of modest length podands (PEG, M.W. avg ϭ 1000) that were doubly cationized by different alkali metal ions. These complexes are abbreviated as [M 1 ϩ M 2 ϩ (EOx)], where M 1 ϩ and M 2 ϩ are different alkali metal ions, EO ϭ ethylene oxide unit, and x ϭ degree of polymerization. This study of the doubly cationized PEG has permitted an in situ measure of the relative binding strength of the cumulative ion-dipole bonds when a single PEG molecule coordinates to the s-orbital of two different alkali metal ions.The dissociation of these complexes inside a quadrupole ion trap is a form of the kinetic method [36,37]. In this variation, rather than sandwiching a single cation between two ligands, a single ligand that was large enough to bind two different metal ions was

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The different faces of poly(ethylene glycol)

Cited by 279 publications

References 10 publications

Coupling of the fusion and budding of giant phospholipid vesicles containing macromolecules

Coupling of the fusion and budding of giant phospholipid vesicles containing macromolecules

Surface-Bound Proteins with Preserved Functionality

Poly(ethylene glycol) doubly and singly cationized by different alkali metal ions: Relative cation affinities and cation-dependent resolution in a quadrupole ion trap mass spectrometer

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