Glycol Derivatives Research Articles

Permeability and separation coefficient of carbon dioxide through glycol derivative supported liquid membrane

Permeabilities of carbon dioxide through glycol derivative supported liquid membranes were measured at 30–70°C by a sweep gas method. The species of glycol derivative used in this work are glycerol, monoethylene glycol, diethylene glycol, triethylene glycol, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol monomethyl ether and triethylene glycol monobutyl ether. The supported liquid membrane was prepared by the impregnation of the porous membrane with glycol derivative solvent. The total pressures at feed and permeate sides were 1.2atm and atmospheric pressure, respectively. The effects of the glycol derivative species and temperatures on CO2 permeability were investigated. The supported liquid membranes with triethylene glycol monomethyl ether and triethylene glycol monobutyl ether result in the CO2 permeabilities higher than those in the case of the other glycol membranes. The lowest permeabilities of CO2 are obtained with glycerol due to the high viscosity. The stabilities of the glycol liquid membranes were also evaluated by the weight fraction loss of the liquid membrane at 30–70°C. The stabilities of the supported liquid membranes using monoethylene glycol, diethylene glycol monomethyl ether and diethylene glycol monoethyl ether are low compared with those of triethylene glycol, triethylene glycol monomethyl ether and triethylene glycol monobutyl ether. The separation coefficients of carbon dioxide and nitrogen through the membranes with triethylene glycol monomethyl ether give the separation coefficient higher than those with triethylene glycol monobutyl ether.

Clickable Poly(ethylene glycol)‐Based Copolymers Using Azide–Alkyne Click Cycloaddition‐Mediated Step‐Growth Polymerization

The design, synthesis, and post‐polymerization functionalization of linear poly(ethylene glycol) (PEG)‐based polytriazole copolymers containing thiol‐reactive maleimide functional groups as pendant side chains are described. A copper(I)‐catalyzed Huisgen‐type 1,3‐dipolar cycloaddition reaction is utilized to prepare copolymers through a combination of diazide‐ and dialkyne‐functionalized triethylene glycol derivatives, along with a dialkyne‐functionalized furan‐protected maleimide‐containing monomer. After the polymerization, a microwave‐assisted retro‐Diels–Alder reaction is utilized to unmask the pendant maleimide groups by removal of the furan moieties. Post‐polymerization modifications of these PEG‐based copolymers containing the furan‐protected maleimide group are accomplished using a photoinitiated radical thiol‐ene reaction, whereas polymers containing the reactive maleimide group are functionalized using the Diels–Alder and nucleophilic thiol‐ene reactions. The nucleophilic thiol‐ene reaction is utilized to fabricate hydrogels by treatment of the maleimide‐containing PEG polymers with dithiol‐containing crosslinkers. Facile functionalization of thus‐obtained hydrogels under mild conditions is demonstrated through the treatment of the residual maleimide groups within the hydrogel with a thiol‐containing fluorescent dye. image

Monodisperse superparamagnetic nanoparticles by thermolysis of Fe(III) oleate and mandelate complexes

Monodisperse superparamagnetic iron oxide nanoparticles of controlled size were synthesized by thermal decomposition of organic iron compounds in different high-boiling solvents in the presence of oleic acid and/or oleylamine. The compounds included Fe(III) oleate and mandelate, formed from FeCl3 and the respective acids. The size of the nanoparticles was easily tuned to 8–27 nm by varying the experimental conditions. The nanoparticles were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and magnetization measurements. The hydrophobic coating of the particles was analyzed by thermogravimetric analysis (TGA) and atomic absorption spectroscopy (AAS). To make the particles biocompatible and water dispersible, nontoxic hydrophilic poly(ethylene glycol) derivatives were synthesized and used for phase transfer of hydrophobic particles into water using a ligand-exchange procedure.

New 5-modified 2′-deoxyuridine derivatives: synthesis and antituberculosis activity

New 2′-deoxyuridine derivatives containing long-chain hydrophilic substituents or hydrophilic groups at the 5 position of uracil were synthesized. 5-[4-(2-Carboxyethylcarbonylamino)-butyloxymethyl]-2′-deoxyuridine completely inhibits the growth of Mycobacterium tuberculosis at a concentration of 50 μg mL−1. However, oligo(ethylene glycol) derivatives do not exhibit activity even at high concentrations.

Thermoresponsive Self-assembly and Conformational Changes of Amphiphilic Monodisperse Short Poly(ethylene glycol)s in Water

Abstract Physicochemical and supramolecular properties of monodisperse amphiphilic short poly(ethylene glycol)s (PEGs) bearing a phenyl group at the one end are studied to investigate the effects of substitution and length of the PEG unit on these properties. It was found that the aromatic substitution encourages these molecules to adopt gauche conformation at the neighboring ethylene units of PEGs and that the octaethylene glycol derivative revealed more PEG-like thermal response of aggregation than the tetraethylene glycol derivative.

Improved production of recombinant human Fas ligand extracellular domain in Pichia pastoris: yield enhancement using disposable culture-bag and its application to site-specific chemical modifications.

BackgroundA useful heterologous production system is required to obtain sufficient amounts of recombinant therapeutic proteins, which are often necessary for chemical characterization and engineering studies on the development of molecules with improved properties. Human Fas ligand extracellular domain (hFasLECD) is an agonistic death ligand protein that has potential applications for medical purposes. Site-specific chemical modifications can provide a powerful means for the development of engineered proteins with beneficial functions. This study aimed to enhance the yield of hFasLECD using a Pichia pastoris secretory expression system suitable for efficient production on a small laboratory scale, and further to provide procedures for its site-specific chemical modification without impairing the biological functions based on the developed production system.ResultsA convenient cultivation system using a disposable plastic bag provided a three-fold increase in purification yield of tag-free hFasLECD as compared with the conventional system using a baffled glass flask. The system was further applied to the production of a mutant, which contains an additional reactive cysteine residue in the N-terminal tag-sequence region. Site-specific conjugations and cross-linking without impairing biological functions were achieved by reaction of the mutant hFasLECD with single maleimide group containing compounds and a linear polyethylene glycol derivative containing two maleimide groups at either end, respectively. All purified tag-free and chemically modified hFasLECDs showed an evident receptor binding activity in co-immunoprecipitation experiments mediated by wild-type and N-glycosylation site deficient mutant human Fas receptor extracellular domain derivatives. An N-Ethylmaleimide conjugated hFasLECD derivative demonstrated a significant cytotoxic activity against human HT-29 colorectal cancer cells.ConclusionsA new, efficient cultivation system for enhanced secretory production of hFasLECD using P. pastoris and an effective strategy for site-specific chemical modifications of hFasLECD were devised. The results obtained constitute the basis for biomedical applications including developments of novel therapeutic proteins and diagnostic tools targeted to related diseases and their biomarkers.

ChemInform Abstract: The Suzuki Cross‐Coupling Reaction in Pure Water Catalyzed by Ligandless Palladium Using Polyethylene Glycol Derivatives as Surfactant.

AbstractUse of the polyethylene glycol derivative PEGS as surfactant allows for very rapid Pd‐catalyzed Suzuki cross‐coupling reactions in water.

Preparation of Polyimide–Cellulose Composite Using Oligoimide with Ethynyl Terminals

Abstract A soluble imide oligomer (IO) (repeating number; 2 and 4) having N-phenylated melamine units and phenylethynyl terminals was prepared, and the application to polyimide composites with cellulose (CEL) crystals derived from pulp (CELp) or Halocynthia (CELh) with or without a modifier was investigated. The CELh additive up to 0.5 wt % was easily dispersed in IO matrix in solution, and thermostable (glass-transition temperature, ca. 285 °C) transparent tough film (tensile strength, ca. 169 MPa; elongation at break, ca. 8.9%; tensile modulus, ca. 4.6 GPa) was obtained, while the addition of a modifier such as cetyltrimethylammonium bromide and poly(ethylene glycol) derivatives was necessary to obtain a similar tough film for the CELp additive.

‘Smart’ gold nanoshells for combined cancer chemotherapy and hyperthermia

Nanomaterials that circulate in the body have great potential in the diagnosis and treatment of diseases. Here we report that ‘smart’ gold nanoshells can carry a drug payload, and that their intrinsic near-infrared (NIR) plasmon resonance enables the combination of chemotherapeutic and hyperthermia therapies. The ‘smart’ gold nanoshells (named DOX/A54@GNs) consist of (a) gold nanoshells (GNs) with NIR plasmon resonance, which not only act as nanoblocks but also produce local heat to allow hyperthermia; (b) an anticancer drug, doxorubicin (DOX), which was conjugated onto the nanoblocks by pH-dependent biodegradable copolymer thiol poly(ethylene glycol) derivatives via carbamate linkage; and (c) the targeting peptide A54 (AGKGTPSLETTP) to facilitate its orientation to liver cancer cells and enhance cellular uptake. The conjugated DOX was released from the DOX/A54@GNs much more rapidly in an acidic environment (pH 5.3) than in a neutral environment (pH 7.4), which is a desirable characteristic for intracellular tumor drug release. DOX-modified GNs showed pH-dependent release behavior, and the in vitro cell uptake experiment using ICP-AES and microscopy showed greater internalization of A54-modified GNs in the human liver cancer cell line BEL-7402 than of those without A54. Flow cytometry and fluoroscopy analysis were conducted to reveal the enhanced cell apoptosis caused by the A54-modified GNs under combined chemotherapeutic and hyperthermia therapies. These results imply that DOX/A54@GNs could be used as a multifunctional nanomaterial system with pH-triggered drug-releasing properties for tumor-targeted chemotherapy and hyperthermia.

Mixed Polyethylene Glycol-Modified Breviscapine-Loaded Solid Lipid Nanoparticles for Improved Brain Bioavailability: Preparation, Characterization, and In Vivo Cerebral Microdialysis Evaluation in Adult Sprague Dawley Rats

Breviscapine is used in the treatment of ischemic cerebrovascular diseases, but it has a low bioavailability in the brain due to its poor physicochemical properties and the activity of P-glycoprotein efflux pumps located at the blood-brain barrier. In the present study, breviscapine-loaded solid lipid nanoparticles (SLN) coated with polyethylene glycol (PEG) derivatives were formulated and evaluated for their ability to enhance brain bioavailability. The SLNs were either coated with polyethylene glycol (40) (PEG-40) stearate alone (Bre-GBSLN-PS) or a mixture of PEG-40 stearate and 1,2-distearoyl-sn-glycero-3-phosphoethanolamine-N-PEG2000 (DSPE-PEG2000) (Bre-GBSLN-PS-DSPE) and were characterized both in vitro and in vivo. The mean particle size, polydispersity index, and entrapment efficiency for Bre-GBSLN-PS and Bre-GBSLN-PS-DSPE were 21.60 ± 0.10 and 22.60 ± 0.70nm, 0.27 ± 0.01 and 0.26 ± 0.04, and 46.89 ± 0.73% and 47.62 ± 1.86%, respectively. The brain pharmacokinetic parameters revealed that the brain bioavailability of breviscapine from the Bre-GBSLN-PS and Bre-GBSLN-PS-DSPE was significantly enhanced (p < 0.01) with the area under concentration-time curve (AUC) of 1.59 ± 0.39 and 1.42 ± 0.58μgh/mL of breviscapine, respectively, in comparison to 0.11 ± 0.02μgh/mL from the commercial breviscapine injection. The ratios of the brain AUC for scutellarin in comparison with the plasma scutellarin AUC for commercial breviscapine injection, Bre-GBSLN-PS, and Bre-GBSLN-PS-DSPE were 0.66%, 2.82%, and 4.51%, respectively. These results showed that though both SLN formulations increased brain uptake of breviscapine, Bre-GBSLN-PS-DSPE which was coated with a binary combination of PEG-40 stearate and DSPE-PEG2000 had a better brain bioavailability than Bre-GBSLN-PS. Thus, the coating of SLNs with the appropriate PEG derivative combination could improve brain bioavailability of breviscapine and can be a promising tool for brain drug delivery.

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

A “sheath” fluid passing through a microfluidic channel at low Reynolds number can be directed around another “core” stream and used to dictate the shape as well as the diameter of a core stream. Grooves in the top and bottom of a microfluidic channel were designed to direct the sheath fluid and shape the core fluid. By matching the viscosity and hydrophilicity of the sheath and core fluids, the interfacial effects are minimized and complex fluid shapes can be formed. Controlling the relative flow rates of the sheath and core fluids determines the cross-sectional area of the core fluid. Fibers have been produced with sizes ranging from 300 nm to ~1 mm, and fiber cross-sections can be round, flat, square, or complex as in the case with double anchor fibers. Polymerization of the core fluid downstream from the shaping region solidifies the fibers. Photoinitiated click chemistries are well suited for rapid polymerization of the core fluid by irradiation with ultraviolet light. Fibers with a wide variety of shapes have been produced from a list of polymers including liquid crystals, poly(methylmethacrylate), thiol-ene and thiol-yne resins, polyethylene glycol, and hydrogel derivatives. Minimal shear during the shaping process and mild polymerization conditions also makes the fabrication process well suited for encapsulation of cells and other biological components.

Microfluidic Fabrication of Polymeric and Biohybrid Fibers with Predesigned Size and Shape

A “sheath” fluid passing through a microfluidic channel at low Reynolds number can be directed around another “core” stream and used to dictate the shape as well as the diameter of a core stream. Grooves in the top and bottom of a microfluidic channel were designed to direct the sheath fluid and shape the core fluid. By matching the viscosity and hydrophilicity of the sheath and core fluids, the interfacial effects are minimized and complex fluid shapes can be formed. Controlling the relative flow rates of the sheath and core fluids determines the cross-sectional area of the core fluid. Fibers have been produced with sizes ranging from 300 nm to ~1 mm, and fiber cross-sections can be round, flat, square, or complex as in the case with double anchor fibers. Polymerization of the core fluid downstream from the shaping region solidifies the fibers. Photoinitiated click chemistries are well suited for rapid polymerization of the core fluid by irradiation with ultraviolet light. Fibers with a wide variety of shapes have been produced from a list of polymers including liquid crystals, poly(methylmethacrylate), thiol-ene and thiol-yne resins, polyethylene glycol, and hydrogel derivatives. Minimal shear during the shaping process and mild polymerization conditions also makes the fabrication process well suited for encapsulation of cells and other biological components.

Fully biodegradable antibacterial hydrogels via thiol–ene “click” chemistry

Novel biodegradable antimicrobial hydrogels, which are promising for use as biomaterials, were prepared facilely via a thiol–ene “click” reaction under human physiological conditions using multifunctional poly(ethylene glycol) (PEG) derivatives as precursors.

A computer simulation of the networked structure of a hydrogel prepared from a tetra-armed star pre-polymer

We used a coarse-grained (CG) molecular dynamics model with potentials convertible to actual units to simulate the polymerization of a gel of a tetra-armed poly(ethylene glycol) derivative (MW ≈ 6000) under aqueous conditions and analysed its three-dimensional network structure. The radius of gyration of individual pre-polymers after gelation was slightly increased compared with that of the single pre-polymer before gelation, and its distribution was broad, attributable to inter- and intra-molecular bonds. The largest pores in the unit cell were about 3.5-3.9 nm. The existence of large pores seems to explain the protein encapsulation capability of and protein leakage from the gel indicating that the CG simulation, which maintains information about potentials in actual units, is an effective tool for investigating gel properties that are difficult to measure in real experiments.

ChemInform Abstract: One‐Step Protection‐Free Synthesis of 3‐Aryl‐5‐hydroxyalkyl‐1,2,4‐oxadiazoles as Building Blocks.

AbstractA simple and straightforward route for the synthesis of the title substituted oxadiazoles via reaction of arylamidoximes (I) with glycolate derivatives is developed.

A tetra(ethylene glycol) derivative of benzothiazole aniline ameliorates dendritic spine density and cognitive function in a mouse model of Alzheimer's disease

We recently reported that the tetra(ethylene glycol) derivative of benzothiazole aniline, BTA-EG4, acts as an amyloid-binding small molecule that promotes dendritic spine density and cognitive function in wild-type mice. This raised the possibility that BTA-EG4 may benefit the functional decline seen in Alzheimer's disease (AD). In the present study, we directly tested whether BTA-EG4 improves dendritic spine density and cognitive function in a well-established mouse model of AD carrying mutations in APP, PS1 and tau (APPswe;PS1M146V;tauP301L, 3xTg AD mice). We found that daily injections of BTA-EG4 for 2weeks improved dendritic spine density and cognitive function of 3xTg AD mice in an age-dependent manner. Specifically, BTA-EG4 promoted both dendritic spine density and morphology alterations in cortical layers II/III and in the hippocampus at 6–10months of age compared to vehicle-injected mice. However, at 13–16months of age, only cortical spine density was improved without changes in spine morphology. The changes in dendritic spine density correlated with Ras activity, such that 6–10month old BTA-EG4 injected 3xTg AD mice had increased Ras activity in the cortex and hippocampus, while 13–16month old mice only trended toward an increase in Ras activity in the cortex. Finally, BTA-EG4 injected 3xTg AD mice at 6–10months of age showed improved learning and memory; however, only minimal improvement was observed at 13–16months of age. This behavioral improvement corresponds to a decrease in soluble Aβ 40 levels. Taken together, these findings suggest that BTA-EG4 may be beneficial in ameliorating the synaptic loss seen in early AD.

Polymer-Mediated Formation and Assembly of Silver Nanoparticles on Silica Nanospheres for Sensitive Surface-Enhanced Raman Scattering Detection

To impart a desired optical property to metal nanoparticles (NPs) suitable for surface-enhanced Raman scattering (SERS) applications, it is crucial to assemble them in two or three dimensions in addition to controlling their size and shape. Herein, we report a new strategy for the synthesis and direct assembly of Ag NPs on silica nanospheres (AgNPs-SiNS) in the presence of poly(ethylene glycol) (PEG) derivatives such as PEG-OH, bis(amino)-PEGs (DA-PEGs), and O,O'-bis(2-aminopropyl)PEG (DAP-PEG). They exhibited different effects on the formation of Ag NPs with variable sizes (10-40 nm) and density on the silica surface. As the molecular weight (MW) of DA-PEGs increased, the number of Ag NPs on the silica surface increased. In addition, DAP-PEG (MW of 2000), which has a 2-aminopropyl moiety at both ends, promoted the most effective formation and assembly of uniform-sized Ag NPs on a silica surface, as compared to the other PEG derivatives with the same molecular weight. Finally, we demonstrated that AgNPs-SiNS bearing 4-fluorobenzenethiol on its surface induced the strong SERS signal at the single-particle level, indicating that each hybrid particle has internal hot spots. This shows the potential of AgNPs-SiNS for SERS-based sensitive detection of target molecules.

In Situ Surface Chemical Modification of Thin-Film Composite Forward Osmosis Membranes for Enhanced Organic Fouling Resistance

Forward osmosis (FO) is an emerging membrane-based water separation process with potential applications in a host of environmental and industrial processes. Nevertheless, membrane fouling remains a technical obstacle affecting this technology, increasing operating costs and decreasing membrane life. This work presents the first fabrication of an antifouling thin-film composite (TFC) FO membrane by an in situ technique without postfabrication treatment. The membrane was fabricated and modified in situ, grafting Jeffamine, an amine-terminated poly(ethylene glycol) derivative, to dangling acyl chloride surface groups on the nascent polyamide active layer. Surface characterization by contact angle, Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), zeta potential, atomic force microscopy (AFM), and fluorescence microscopy, confirms the presence of Jeffamine on the membrane surface. We demonstrate the improved fouling resistance of the in situ modified membranes through accelerated dynamic fouling FO experiments using a synthetic wastewater feed solution at high concentration (250 mg/L) of alginate, a model macromolecule for the hydrophilic fraction of wastewater effluent organic matter. Our results show a significantly lower flux decline for the in situ modified membranes compared to pristine polyamide (14.3 ± 2.7% vs 2.8 ± 1.4%, respectively). AFM adhesion force measurements between the membrane and a carboxylate-modified latex particle, a surrogate for the organic (alginate) foulant, show weaker foulant-membrane interactions, further confirming the enhanced fouling resistance of the in situ modified membranes.

The characterization of dendronized poly(ethylene glycol)s and poly(ethylene glycol) multi-arm stars using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry

The synthesis of branched poly(ethylene glycol) (PEG) derivatives, namely star PEG and dendronized PEG, can be challenging and their purity can be difficult to ascertain using traditional techniques, such as NMR and GPC. Herein, the detailed characterization of these branched PEGs using MALDI-ToF MS was investigated in order to confirm their structural purity. In this light, mass spectrometry offers a number of advantages for polymer characterization, including the ability to get detailed structural data, such as end group masses, from microgram-scale samples. In addition, the ability to rapidly acquire data from crude reaction aliquots makes MALDI-ToF MS ideal for monitoring end group transformations.

Thermoresponsive dendrimers based on oligoethylene glycols: Design, synthesis and cytotoxic activity against MCF-7 breast cancer cells

Three interesting thermoresponsive branched oligoethylene glycol dendrimers based on tetrabromohydroquinone were efficiently synthesized from tetrabromohydroquinone and three different oligoethylene glycol derivatives. By visual inspection, all these dendrimers are water-soluble at room temperature. The thermoresponsive behaviors were investigated by using UV/vis turbidity measurement at different temperatures for 0.25 wt% of aqueous solutions from D1, D2 and D3. The cytotoxicity of the prepared dendrimers was tested against MCF-7 breast cancer cells. All tested dendrimers showed considerable results, where D2 dendrimer gave the best result; it showed cytotoxicity against MCF-7 cell line with IC50 of 1.07 μg/mL and resistant fraction equals 1.97%, the other two dendrimers showed a modest cytotoxic profile.