Lubricin: a versatile, biological anti-adhesive with properties comparable to polyethylene glycol

Lubricin is a glycoprotein found in articular joints which has been recognized as being an important biological boundary lubricant molecule. Besides providing lubrication, we demonstrate, using a quartz crystal microbalance, that lubricin also exhibits anti-adhesive properties and is highly effective at preventing the non-specific adsorption of representative globular proteins and constituents of blood plasma. This impressive anti-adhesive property, combined with lubricin's ability to readily self-assemble to form dense, highly stable telechelic polymer brush layers on virtually any substrates, and its innate biocompatibility, makes it an attractive candidate for anti-adhesive and anti-fouling coatings. We show that coatings of lubricin protein are as effective as, or better than, self-assembled monolayers of polyethylene glycol over a wide range of pH and that this provides a simple, versatile, highly stable, and highly effective method of controlling unwanted adhesion to surfaces.

Biodegradable polyethylene glycol-based ionic liquids for effective inhibition of shale hydration

A series of ionic liquids based on polyethylene glycol (PEG) with different molecular weights were prepared for inhibiting shale hydration and swelling. The antiswelling ratio was measured to investigate the effect of different PEG-based ionic liquids on bentonite volume expansion, and it has shown that the ionic liquid based PEG200, i.e. PEG with molecular weight of 200, exhibited superior inhibition. The structures of the PEG200-based ionic liquids were characterized by ¹H NMR studies. The XRD results indicated that the PEG200-based ionic liquids intercalated into sodium montmorillonite (Na-MMT) reducing the water uptake by the clay. The formation of complexes of Na-MMT and PEG200-based ionic liquids was also verified by FTIR spectroscopy. Thermal degradation analysis suggested that the PEG200-based ionic liquids accessed the interlamellar spaces of Na-MMT and reduced the water content of the complexes obtained. Moreover, no breaks and collapse were observed on the shale samples after immersion in PEG200-based ionic liquid solutions. All the PEG200-based ionic liquids showed biodegradability and potential application in effective inhibition for clay hydration.

Blue electrogenerated chemiluminescence from water-soluble iridium complexes containing sulfonated phenylpyridine or tetraethylene glycol derivatized triazolylpyridine ligands

Incorporating phenylpyridine- and triazolylpyridine-based ligands decorated with methylsulfonate or tetraethylene glycol (TEG) groups, a series of iridium(III) complexes has been created for green and blue electrogenerated chemiluminescence under analytically useful aqueous conditions, with tri-n-propylamine as a coreactant. The relative electrochemiluminescence (ECL) intensities of the complexes were dependent on the sensitivity of the photodetector over the wavelength range and the pulse time of the applied electrochemical potential. In terms of the integrated area of corrected ECL spectra, with a pulse time of 0.5 s, the intensities of the Ir(III) complexes were between 18 and 102 % that of [Ru(bpy)3 ](2+) (bpy=2,2'-bipyridine). However, when the intensities were measured with a typical bialkali photomultiplier tube, the signal of the most effective blue emitter, [Ir(df-ppy)2 (pt-TEG)](+) (df-ppy=2-(2,4-difluorophenyl)pyridine anion, pt-TEG=1-(2-(2-(2-(2-hydroxyethoxy)ethoxy)ethoxy)ethyl)-4-(2-pyridyl)-1,2,3-triazole), was over 1200 % that of the orange-red emitter [Ru(bpy)3 ](2+) . A combined experimental and theoretical investigation of the electrochemical and spectroscopic properties of the Ir(III) complexes indicated that the greater intensity from [Ir(df-ppy)2 (pt-TEG)](+) relative to those of the other Ir(III) complexes resulted from a combination of many factors, rather than being significantly favored in one area.

Analytically useful blue chemiluminescence from a water-soluble iridium(iii) complex containing a tetraethylene glycol functionalised triazolylpyridine ligand

We examine [Ir(df-ppy)2(pt-TEG)](+) as the first highly water soluble, blue-luminescent iridium(iii) complex for chemiluminescence detection. Marked differences in selectivity were observed between the new complex and the conventional [Ru(bpy)3](2+) reagent, which will enable this mode of detection to be extended to new areas of application.

Nano-capsules of amphiphilic poly (ethylene glycol)-block-poly (bisphenol A carbonate) copolymers via thermodynamic entrapment

The synthesis of amphiphilic poly(ethylene glycol)-block-poly(bisphenol A carbonate) (PEG-b-PC) block copolymer is presented here using a simple bio-chemistry coupling reaction between poly(bisphenol A carbonate) (PC) with a monomethylether poly(ethylene glycol) (mPEG-OH) block, mediated by dicyclohexylcarbodiimide/4-dimethylaminopyridine. This method inherently allows great flexibility in the choice of starting materials as well as easy product purification only requiring phase separation and water washing. Collective data from Fourier transform infrared spectroscopy (FTIR), nuclear magnetic resonance spectroscopy (NMR) and modulated dynamic scanning calorimetry (MDSC) confirmed the successful attachment of the poly(ethylene glycol) (mPEG-OH) and poly(bisphenol A carbonate) (PC) blocks. The preparation of nano-capsules was carried out by sudden addition of water to PEG-b-PC copolymers dispersed in THF, resulting in the controlled precipitation (i.e. thermodynamic entrapment) of the copolymer. Nano-capsules as small as 85 nm ± 30 nm were produced using this simple and fast methodology. We also demonstrate that encapsulating a water-insoluble bisphenol A diglycidyl ether (DGEBA) epoxy resin is possible highlighting the potential use of these capsules as a chemical delivery system.

Synthesis and self-assembly behaviour of poly(Nα-Boc-l-tryptophan)-block-poly(ethylene glycol)-block-poly(Nα-Boc-l-tryptophan)

We report for the first time the use of Nα-Boc-l-tryptophan for the synthesis of amphiphilic BAB triblock copolymers for potential drug delivery applications. A library of poly(Nα-Boc-l-tryptophan)-block-poly(ethylene glycol)-block-poly(Nα-Boc-l-tryptophan) (PBoclTrp-b-PEG-b-PBoclTrp) amphiphilic copolymers were synthesized through the ring opening polymerization of Nα-Boc-l-tryptophan Nα-carboxy anhydride as initiated by diamino-terminated PEG of fixed molecular weight (Mn 3350). The influence of the hydrophobic block length over self-assembly was investigated for 4 of the BAB copolymers of molecular weights varying between Mn 5000 and Mn 17000. It was found that an increase in hydrophobic block length led to an increase in hydrodynamic size of aggregates in solution, as well as a decrease in critical micelle concentration. TEM analysis showed the formation of spherical micelles with the largest of the copolymers forming interconnected networks of spherical micelles. The influence of hydrophobic block length over the formation of secondary structure was analyzed using circular dichroism and infrared spectroscopy. Collectively we found that the presence of t-Boc protected l-tryptophan leads to the preferential formation of α-helix secondary structure through hydrogen bonding, which, in a drug delivery vehicle context, could help in controlling drug release. Also, it is believed that the use of novel Nα-Boc-l-tryptophan could improve drug stabilization in the hydrophobic core via π-π interactions between indole rings.

Enhanced homogeneity and interfacial compatibility in melt-extruded cellulose nano-fibers reinforced polyethylene via surface adsorption of poly(ethylene glycol)-block-poly(ethylene) amphiphiles

In this paper, we demonstrate that an amphiphilic block copolymer such as polyethylene glycol-b-polyethylene can be used as both dispersing and interfacial compatibilizing agent for the melt compounding of LLDPE with cellulose nano-fibers. A simple and effective spray drying methodology was first used for the first time for the preparation of a powdered cellulose nano-fibers extrusion feedstock. Surface adsorption of the amphiphilic PEG-b-PE was carried out directly in solution during this process. These various dry cellulosic feedstock were subsequently combined with LLDPE via extrusion to produce a range of nano-composites. The collective outcomes of this research are several folds. Firstly we show that presence of surface adsorbed PEG-b-PE effectively hindered the aggregation of the cellulose nano-fibers during the extrusion, affording clear homogenous materials with minimum aggregation even at the highest loading of cellulose nano-fibers (∼23 vol.%). Secondly, the tailored LLDPE/cellulose interface arising from intra- and inter-molecular hydrogen and Van der Waals bonds yielded significant levels of mechanical improvements in terms of storage and tensile modulus. We believe this study provides a simple technological template to produce high quality and performant polyolefins cellulose-based nano-composites.

Molecular interactions behind the synergistic effect in mixed monolayers of 1-octadecanol and ethylene glycol monooctadecyl ether

Mixed monolayers of 1-octadecanol (C18OH) and ethylene glycol monooctadecyl ether (C18E1) were studied to assess their evaporation suppressing performance. An unexpected increase in performance and stability was found around the 0.5:0.5 bicomponent mixture and has been ascribed to a synergistic effect of the monolayers. Molecular dynamics simulations have attributed this to an additional hydrogen bonding interaction between the monolayer and water, due to the exposed ether oxygen of C18E1 in the mixed system compared to the same ether oxygen in the pure C18E1 system. This interaction is maximized around the 0.5:0.5 ratio due to the particular interfacial geometry associated with this mixture.