Polyethylene Glycol-polypropylene Glycol Research Articles

Poly(gamma-glutamic acid) based thermosetting hydrogels for injection: Rheology and functional parameters evaluation

Biocompatible thermosetting hydrogels are attractive compounds either for the delivery of drugs or as medical devices for tissue regeneration purposes. In this work Poly(Gamma-Glutamic Acid) (G-PGA) and G-PGA based hydrogels were explored. The hypothesis was to evaluate G-PGA and crosslinking agents combinations in order to obtain thermosetting hydrogels suitable for injection. Attention focused on hydrogels that can form by ionic interaction with compounds bearing amine groups, and/or by interaction with polymers such as chitosan and symmetric triblock copolymer (polyethylene glycol-polypropylene glycol- polyethylene glycol). Polymer solutions and related hydrogels characterization involved: rheologic behavior, osmolarity, syringeability and injectability.Results showed that G-PGA solutions syringeability was always acceptable, while injectability test did not meet aspiration by 22G needle. Osmolarity value suitable for injection could be obtain by adding buffering solutions. Only ternary blends made of chitosan, sodium beta-glyceroposphate and G-PGA, or G-PGA, Pluronic F68 and l-lysine, with fixed compositions, resulted in thermosetting gels. The obtained thermosetting gels were not reversible.

Truxene-Based Hyperbranched Conjugated Polymers: Fluorescent Micelles Detect Explosives in Water.

We report two hyperbranched conjugated polymers (HCP) with truxene units as core and 1,4-didodecyl-2,5-diethynylbenzene as well as 1,4-bis(dodecyloxy)-2,5-diethynylbenzene as comonomers. Two analogous poly(para-phenyleneethynylene)s (PPE) are also prepared as comparison to demonstrate the difference between the truxene and the phenyl moieties in their optical properties and their sensing performance. The four polymers are tested for nitroaromatic analytes and display different fluorescence quenching responses. The quenching efficiencies are dependent upon the spectral overlap between the absorbance of the analyte and the emission of the fluorescent polymer. Optical fingerprints are obtained, based on the unique response patterns of the analytes toward the polymers. With this small sensor array, one can distinguish nine nitroaromatic analytes with 100% accuracy. The amphiphilic polymer F127 (a polyethylene glycol-polypropylene glycol block copolymer) carries the hydrophobic HCPs and self-assembles into micelles in water, forming highly fluorescent HCP micelles. The micelle-bound conjugated polymers detect nitroaromatic analytes effectively in water and show an increased sensitivity compared to the sensing of nitroaromatics in organic solvents. The nitroarenes are also discriminated in water using this four-element chemical tongue.

Co-micellized Pluronic mixture with thermo-sensitivity and residence stability as an injectable tissue adhesion barrier hydrogel.

Although the tissue adhesion which leads to various complications frequently occurs after surgery, the development of an ideal tissue adhesion barrier is still a challenge. In this study, a thermo-sensitive hydrogel, which can fulfill the essential requirements of tissue adhesion barrier (that is, ease of handling for surgeon, flowing down prevention after application, stable residence on the injury during wound healing, and no use of toxic additives), was developed using biocompatible polyethylene glycol-polypropylene glycol copolymers (Pluronic F127/F68/P123 mixture). From the in vitro cell culture and in vivo animal study, it was observed that the Pluronic mixtures showed sol-gel transition at approximately body temperature (for easy injection or coating on the injury site and flowing down prevention after application) and prolonged residence stability in aqueous environment (> ∼7 days for stable protection of injury tissues/organs during wound healing), and thus was highly effective for the prevention of tissue adhesion without adverse tissue responses. Based on these results, the Pluronic F127/F68/P123 mixture itself (without any additives) can be a good candidate as an injectable or coatable tissue adhesion barrier hydrogel applicable to various injury tissues in terms of ease of use, effectiveness, and safety. © 2016 Wiley Periodicals, Inc. J Biomed Mater Res Part B: Appl Biomater, 106B: 172-182, 2018.

Aqueous two-phase system purification for superoxide dismutase induced by menadione from Phanerochaete chrysosporium

In the present work, the partitioning behavior of menadione-induced superoxide dismutase (SOD; EC 1.15.1.1), an antioxidant enzyme that has various applications in the medical and cosmetic industries, from the white rot fungus Phanerochaete chrysosporium has been characterized on different types of aqueous two-phase systems (ATPSs) (poly(ethylene glycol)/polypropylene glycol (PEG/PPG)-dextran, PEG-salt and PPG-salt). PEG-salt combinations were found most optimal systems for the purification of SOD. The best partition conditions were found using the PEG-3350 24% and K2HPO4 5% (w/w) with pH 7.0 at 25 °C. The partition coefficient of total SOD activity and total protein concentration observed in this system were 0.17 and 6.65, respectively, with the recovery percentage as 78.90% in the bottom phase and 13.17% in the top phase. The highest purification fold for SOD from P. chrysosporium was found as 6.04 in the bottom phase of PEG 3350%24 – K2HPO4%5 (w/w) system with pH 7.0. SOD purified from P. chrysosporium was determined to be a homodimer in its native state with a molecular weight of 60 ± 4 kDa. Consequently, simple and only one step PEG-salt ATPS system was developed for SOD purification from P. chrysosporium.

High transition temperature shape memory polymers (SMPs) by telechelic oligomer approach

This work describes the synthesis and comparative shape memory properties of cross-linked networks derived from epoxy and cyanate ester monomers containing polyether oligomers as reactive shape memory segments. The hydroxy telechelic oligomers viz. polyethyleneglycol (PEG), polypropyleneglycol (PPG), and polytetramethyleneglycol (PTG) are reacted with epoxy–cyanate ester matrix resulting in shape memory polymers with high transition temperatures. The soft oligomer segments act as flexible linker unit which interconnect oxazolidone, isocyanurate and triazine ring structures in the cross-linked polymer. The resultant cyclomatrix SMPs exhibit high transition temperatures 132, 178 and 161°C respectively for PEG, PPG and PTG integrated SMPs. The Eg/Er ratios are increased in the order PEG<PTG<PPG. The PTG and PPG based SMPs show shape retention of 99% and shape recovery of >98% with recovery time <100s. All the SMPs display good thermal stabilities (both inert and oxidative) above 275°C.

Analytical mass spectrometry of poly(ethylene glycol) additives in artists’ acrylic emulsion media, artists’ paints, and microsamples from acrylic paintings using MALDI–MS and nanospray-ESI–MS

Poly(ethylene glycol) (PEG) compounds in artists’ acrylic emulsion paint products from different paint manufacturers, ranging from base emulsions (Rohm and Haas, Röhm and Scott Bader), to modified emulsions and complete paints (Rowney, Winsor and Newton, Golden, Liquitex, Lascaux), were characterised with a newly developed mass spectrometric method which combines data from Matrix assisted laser desorption/ionisation mass spectrometry (MALDI–MS) and nano-electrospray ionisation mass spectrometry (nano-ESI–MS(MS)). MALDI–MS was used for the determination of the molar mass distribution (MMD) and calculation of the molar mass averages ( M w and M n), the polydispersity index ( D) and the relative amount of a specific distribution if multiple PEGs were present. Electrospray ionisation mass spectrometry was used for the end-group analysis. Three different classes of polymers was found being PEG, polypropylene glycol (PPG) and a block copolymer of polyethylene glycol/polypropylene glycol (PEG/PPG) with molar mass averages ranging from 400 to 4200 Da. PEG compounds with a nonylphenyl or an octylphenyl hydrophobic end-group are most common. The hydrophilic end-groups observed are hydroxide and/or sulphate. Water extracts of microsamples from a palette by David Hockney dating from 1970 and samples paintings by Patrick Caulfield (1936–2005) and John Hoyland (born in 1934) were investigated with the same technique. Although some artist paint manufacturers use the same specific base emulsions to make their paints, the composition of the PEG compounds present in the water extracts of the palette and paintings samples made it possible, in some cases, to suggest a specific brand of paint used by the artist.

Cyclodextrin–insulin complex encapsulated polymethacrylic acid based nanoparticles for oral insulin delivery

Present investigation was aimed at developing an oral insulin delivery system based on hydroxypropyl β cyclodextrin–insulin (HPβCD–I) complex encapsulated polymethacrylic acid-chitosan-polyether (polyethylene glycol-polypropylene glycol copolymer) (PMCP) nanoparticles. Nanoparticles were prepared by the free radical polymerization of methacrylic acid in presence of chitosan and polyether in a solvent/surfactant free medium. Dynamic light scattering (DLS) experiment was conducted with particles dispersed in phosphate buffer (pH 7.4) and size distribution curve was observed in the range of 500–800 nm. HPβCD was used to prepare non-covalent inclusion complex with insulin and complex was analyzed by Fourier transform infrared (FTIR) and fluorescence spectroscopic studies. HPβCD complexed insulin was encapsulated into PMCP nanoparticles by diffusion filling method and their in vitro release profile was evaluated at acidic/alkaline pH. PMCP nanoparticles displayed good insulin encapsulation efficiency and release profile was largely dependent on the pH of the medium. Enzyme linked immuno sorbent assay (ELISA) study demonstrated that insulin encapsulated inside the particles was biologically active. Trypsin inhibitory effect of PMCP nanoparticles was evaluated using N-α-benzoyl- l-arginine ethyl ester (BAEE) and casein as substrates. Mucoadhesive studies of PMCP nanoparticles were conducted using freshly excised rat intestinal mucosa and the particles were found fairly adhesive. From the preliminary studies, cyclodextrin complexed insulin encapsulated mucoadhesive nanoparticles appear to be a good candidate for oral insulin delivery.

Hydrophilicity, crystallinity and electrostatic dissipating properties of poly(oxyethylene)-segmented polyurethanes

Plaques of poly(oxyethylene)-segmented polyurethanes prepared from isophorone diisocyanate (IPDI) and polyethylene glycol (PEG) were used to probe the structure/property relationships with regard to hydrophilicity, crystallinity and electrostatic dissipating (ESD) ability. The prepared urethane polymers or oligomers consistently exhibited lower surface resistivities than their corresponding PEG-1000, 2000 and 8000 starting materials. The magnitude of the decrease in surface resistivity (ohm/sq) was correlated with heat of crystallinity, measured by differential scanning calorimetry. Surface resistivity as low as 107.5 ohm/sq for PEG-1000/IPDI polyurethane, a decrease by 2.5 orders of magnitude from pure PEG-1000, was observed and attributed to the differences in crystallinity. Polyurethanes containing PEG, polypropylene glycol (PPG) and mixed PEG/PPG were also prepared for comparison. The mixed PEG/MDEA (N -methyl diethanolamine) polyurethanes further demonstrated the importance of the nature and mobility of the hydrophilic groups for lowering the polymer surface resistivity. To account for these observations, an electron conducting mechanism via association and mobility of the hydrogen-bonded water molecules with hydrophilic poly(oxyethylene) groups is suggested. © 1999 Society of Chemical Industry

Physicochemical characterization of PEG-PPG conjugated human urokinase

Human urokinase (UK) was conjugated with polyethylene glycol-polypropylene glycol (PEG-PPG) and its physicochemical properties were examined. PEG-PPG modification decreased the activity for plasminogen activation, but increased the half-life of this protein when injected intravenously in rabbits. Kinetic analysis of PEG-PPG conjugated UK (PEG-PPG-UK) revealed that the kcat for plasminogen activation decreased 1/5-fold with the increase of K m in comparison with that of UK, although these parameters for cleavage of synthetic substrate (S-2444) did not change. However, the inhibitor constant of PEG-PPG-UK for plasminogen activator inhibitor 1 (PAI 1) was equal to that of UK. Peptide mapping analysis revealed that PEG-PPG binding sites were mainly determined to be Lys 35, 46, 61, 98, 120 and 135 in A-chain and Lys 211, 300, 318, 338, 348, 383 and 404 in B-chain. In addition, the modification rates of A and B-chain were 37.8% and 19.8% on average, respectively.

Influence of the mechanical field on the phase equilibrium of polyether mixtures and the cellulose diacetate-acetone-water system

In the shear field and static conditions the authors have studied the phase equilibrium of systems polyethylene glycol-polypropylene glycol and cellulose diacetate-acetone-water. Addition of water to acetone at high temperatures raises and at low temperatures reduces its dissolving capacity in relation to cellulose diacetate. A mechanical field leads to worsening of the compatibility of the polyethers and improvement of the solubility of cellulose acetate in water-acetone mixtures.

非イオン界面活性剤の組成が原油回収効果におよぼす影響について

This study is a basic resarch which has been conducted to investigate the effect of oil recovery by nonionic surfactant flooding under the low concentration of the same. For the purpose, two kinds of surfactant were selected as samples. One of them was polyethylene glycol-polypropylene glycol ether and the other was polyethylene glycol-nonylphenol ether.In the first type, polyethylene glycol-polypropylene glycol ether, we prepare chemicals, which have various mole numbers of ethylene oxide and molecular weight of polypropylene. Concerning their low concentration, the interfacial tension between crude oil and oil recovery efficiency were measured at every temperature.From these results, we recongnized extremely low interfacial tensions and higher recovery of residual oil when molecular weight of polypropylene glycols were 3, 000 to 4, 000 and ethylene oxide contents were 30 to 40 percent at 30°C to 40°C of test temperature.In the second type, nonylphenol ether, the lowest interfacial tensions were obtained at 9 to 10 polymerized degrees of ethylene oxide in these surfactants, but the most recoverable efficiency was shown at 7 to 9 polymerized degrees. We could not get the clear relationship between interfacial tension and recovery efficiency in this type of surfactant.