Oxyethylene Oligomers Research Articles

Flexible antibodies with nonprotein hinges

There is a significant need for antibodies that can bind targets with greater affinity. Here we describe a novel strategy employing chemical semisynthesis to produce symmetroadhesins: antibody-like molecules having nonprotein hinge regions that are more flexible and extendible and are capable of two-handed binding. Native chemical ligation was carried out under mild, non-denaturing conditions to join a ligand binding domain (Aβ peptide) to an IgG1 Fc dimer via discrete oxyethylene oligomers of various lengths. Two-handed Aβ–Fc fusion proteins were obtained in quantitative yield and shown by surface plasmon resonance to bind an anti-Aβ antibody with a KD at least two orders of magnitude greater than the cognate Aβ peptide. MALDI-TOF MS analysis confirmed the protein/nonprotein/protein structure of the two-handed molecules, demonstrating its power to characterize complex protein-nonprotein hybrids by virtue of desorption/ionization mediated by peptide sequences contained therein. We anticipate many applications for symmetroadhesins that combine the target specificity of antibodies with the novel physical, chemical and biological properties of nonprotein hinges.

Preparation of hybrid organic–inorganic materials based on a di-ureasil matrix doped with lithium bis(trifluoromethanesulfonyl)imide

In this presentation we describe the preparation of solvent-free solid polymer electrolytes (SPEs) by the sol–gel route with the incorporation of controlled quantities of lithium bis(trifluoromethanesulfonyl) imide (LiTFSI) into the host matrix. The host framework of these xerogels, designated as di-ureasils and represented by d-U(900), contains oxyethylene oligomers with about 15 repeat units bonded at each end to a siliceous backbone through urea bridging links. Electrolytes were characterized by ionic conductivity measurements, cyclic voltammetry at a gold microelectrode and thermal analysis. The results obtained reveal that these hybrid materials are completely amorphous and exhibit appropriate electrochemical characteristics for a variety of applications.

Thermotropic Aromatic Poly(amide-ether)s

Novel poly(amide ether)s were synthesized from aminophenyl-terminated oxyethylene oligomers and terephthaloyl chloride or 4,4′-biphenyldicarboxylic acid dichloride. The polymers were produced in high yield and high molecular weight (ηinh = 0.8–1.9 dl/g), and were characterized by elemental analyses, NMR spectroscopy and viscosity measurements. They showed low solubility in organic solvents, and a remarkable ability to develop high crystallinity, with melting temperatures in the range 300–370°C. Polymers containing biphenylene units formed stable mesophases (smectic) upon melting, as revealed by calorimetry, optical microscopy and X-ray diffraction.

Microcalorimetric investigation on interaction between poly(acrylic acid) and oxyethylene oligomers in water

The interaction between poly(acrylic acid) (PAA) and oxyethylene oligomers (PEG) was investigated by solution microcalorimetry in water at 25°C. The enthalpy of interaction is endothermic, and, in the case of PEG-400 in large excess, the enthalpic parameter increases sharply with PEG/PAA ratio. No such behaviour was found for PEG-1000 and for dimethylated PEG-400. The apparent monomolar heat capacity of the binary solute was also determined, and the corresponding excess quantity is negative at any PEG/PAA ratio. The two series of microcalorimetric results indicate that PAA and oxyethylene oligomers interact noticeably in water and that a long PAA chain may be regarded as a linear adsorption surface for short PEG chains.

Controlled release of herbicides bound to poly[oligo(oxyethylene) methacrylate] hydrogels

A series of polymeric hydrogels containing different oxyethylene oligomers has been prepared by radical polymerization of oligo(oxyethylene) methacrylate monomers in the presence of different amounts of N, N′-methylenebisacrylamide as crosslinking agent or acrylamide as hydrophilic comonomer. Systemic herbicides, such as 2,4-dichlorophenoxyacetic acid and 4-chloro-2-methylphenoxyacetic acid, were covalently supported on the polymeric hydrogels by esterification of the side chain hydroxyl groups. In the investigated samples, swelling in water depends mainly on the length of the oligo(oxyethylene) side chains, the content of hydrophilic comonomer and, to a minor extent, on the degree of crosslinking. Herbicide loading produces a substantial drop in the water uptake by the polymer. The release of herbicides, investigated at room temperature in water at different pH values, is very much affected by alkalinity and to a lesser extent by the polymer structure.

Effect of end group and solvent on gel permeation chromatography of oligo(oxyethylene) compounds

Samples of three series of homogeneous oxyethylene oligomers: (i) H(OCH 2CH 2) mOH, m in the range 1 to 45; (ii) CH 3(OCH 2CH 2) m,OCH 3, m in the range 2 to 45; (iii) H(CH 2) n(OCH 2CH 2) 4O(CH 2) nH, n = 2, 3, 7, 9; were eluted through a PL-gel low-porosity gel permeation chromatographic column with several solvents; dichloromethane, tetrahydrofuran, 1,1,1-trichloroethane, 1,2,4-trichlorobenzene, and N,N′-dimethylacetamide. The elution volumes of the oligomers were determined by a combination of size-exclusion and partition—adsorption effects.

Sequential Copolymers of Oxyethylene Oligomers and α,ι-Poly(methylenedithiols)

Sequential Copolymers of Oxyethylene Oligomers and α,ι-Poly(methylenedithiols)