Introduction Of PEG Research Articles

Preparation and characterization of polyethylene glycol/poly(L-lactic acid) blends

Abstract The effect of incorporation of poly(ethylene glycol) (PEG) on thermomechanical and hydrophilicity properties of poly(L-lactic acid) (PLLA) was investigated. PEG/PLLA blends, containing 10, 20, 30 and 40 wt% PEG, were prepared by melt-extrusion in a co-rotating twin-screw extruder. By DSC analysis, it was observed that the Tg of PLLA phase in PEG/PLLA blends decreased accompanied by a significant decrease in Tcc and increase in their melting enthalpy. Therefore, the addition of PEG enhances the crystallization ability of PLLA phase due to its lubricating effect which increased mobility of PLLA chains. From TGA it was observed that low concentrations of PEG (10 & 20 wt%) increase the Tonset of thermal degradation, probably due to improved heat resistance of the crystalline phase. At higher PEG content, the Tonset decreases, as the lubricating effect becomes the controlling mechanism for the initiation of degradation process. Decrease in tensile strength and modulus was recorded especially in PLLA blends with PEG content higher than 20 wt%. The elongation at break decreases reaching a maximum at 20 wt% PEG and then dropped again. To investigate the effect of PEG on the wetting ability of PLLA, water contact angle measurements were performed. The results indicate that the introduction of PEG lowers the contact angle values in PEG/PLLA film surfaces, as compared to pure PLLA, suggesting improved hydrophilic properties.

Encapsulation of Lanthanide β-diketone Hybrids in Organic Oligomer Poly(ethylene glycol) 400

The organic ligand 2-Thenoyltrifluoroacetone (TTA) which was selected as molecular bridge for sensitization of europium and terbium ions were modified by 3-(triethoxysilyl)-propylisocyanate (TEPIC) to obtain the hybrid precursor TTA-Si. Then the solution of Eu(NO3)3 and Tb(NO3)3 were added in the presence of tetraethylorthosilicate (TEOS). The binary lanthanide organic/inorganic hybrid material were obtained. The ternary hybrid materials were obtained by adding the solution of Eu(NO3)3 and Tb(NO3)3 and Poly (ethylene glycol) (PEG400). We investigated the thermal stability and luminescence properties of hybrids and found that the ternary hybrid materials exhibit better thermal stability and stronger emission intensity. Furthermore, compared with the binary mesoporous material Eu-(TTA-Si)3 and Tb-(TTA-Si)3, the ternary mesoporous material Eu-(TTA-Si)3-PEG and Tb-(TTA-Si)3-PEG exhibits the characteristic emission of the Eu3+ and Tb3+ ion with a higher luminescence intensity, suggesting that the introduction of PEG is of benefit for the sensitization of Eu3+ and Tb3+ luminescence, by replacing H2O groups that can quench the luminescence of Eu3+ and Tb3+ ions.

Divalent folate modification on PEG: an effective strategy for improving the cellular uptake and targetability of PEGylated polyamidoamine-polyethylenimine copolymer.

The stability and targeting ability of nanocarrier gene delivery systems are necessary conditions to ensure the good therapeutic effect and low nonspecific toxicity of cancer treatment. Poly(ethylene glycol) (PEG) has been widely applied for improving stability and as a spacer for linking ligands and nanocarriers to improve targetability. However, the cellular uptake and endosomal escape capacity of nanocarriers has been seriously harmed due to the introduction of PEG. In the present study, we synthesized a new gene delivery vector by coupling divalent folate-PEG (PEG3.4k-FA2) onto polyamidoamine-polyethylenimine (PME) copolymer (PME-(PEG3.4k-FA2)1.72). Both PEG and monovalent folate-PEG (PEG3.4k-FA1) modified PME were prepared as control polymers, which were named as PME-(PEG3.5k)1.69 and PME-(PEG3.4k-FA1)1.66, respectively. PME-(PEG3.4k-FA2)1.72 exhibited strong DNA condensation capacity like parent polymer PME which was not significantly influenced by PEG. PME-(PEG3.4k-FA2)1.72/DNA complexes at N/P = 10 had a diameter ∼143 nm and zeta potential ∼13 mV and showed the lowest cytotoxicity and hemolysis and the highest transfection efficiency among all tested polymers. In folate receptor positive (FR-positive) cells, the cellular uptake and transfection efficiency were increased with the increase in the number of folates coupled on PEG; the order was PME-(PEG3.4k-FA2)1.72 > PME-(PEG3.4k-FA1)1.66 > PME-(PEG3.5k)1.69. Folate competition assays showed that PME-(PEG3.4k-FA2)1.72 complexes had stronger targeting ability than PME-(PEG3.5k)1.69 and PME-(PEG3.4k-FA1)1.66 complexes due to their higher folate density per PEG molecule. Cellular uptake mechanism study showed that the folate density on PEG could change the endocytosis pathway of PME-(PEG3.5k)1.69 from clathrin-mediated endocytosis to caveolae-mediated endocytosis, leading to less lysosomal degradation. Distribution and uptake in 3D multicellular spheroid assays showed that divalent folate could offer PME-(PEG3.4k-FA2)1.72 complexes stronger penetrating ability and higher cellular uptake. With these advantages, PME-(PEG3.4k-FA2)1.72 may be a promising nonviral vector candidate for efficient gene delivery. This study also indicates that divalent folate modification on PEG can serve as an efficient strategy to improve the cellular uptake and targeting ability of PEGylated cationic polymers for gene delivery.

Synthesis of poly(p-dioxanone)-based block copolymers in supercritical carbon dioxide

Poly(p-dioxanone)–poly(ethylene glycol)–poly(p-dioxanone) triblock copolymers (PPDO–PEG–PPDO) were first synthesized by suspension ring-opening polymerization (ROP) of p-dioxanone (PDO) in supercritical carbon dioxide (scCO2) using different molecular weights (2–10 K) of poly(ethylene glycol) (PEG) as macroinitiators. White and fine flow powders were successfully obtained when the molecular weight of PEG was below 6 K and its feed content below 20 wt.%. The 1H nuclear magnetic resonance (NMR) result indicated the formation of PPDO–PEG–PPDO block structure even in a confined polymerized environment of particles. All the powderous samples contained irregular shaped particles that were observed by scanning electron microscope (SEM). Except for the copolymer with 10 wt.% PEG10K feed content, the mean particle sizes of other powderous samples showed identical values close to 15 μm. This fact was in agreement with the crystallinity of PPDO in the copolymers measured by differential scanning calorimetry (DSC). The water absorption of these copolymers was also measured, and as compared with PPDO homopolymer, the introduction of PEG increased the water absorption of the copolymers. The green and environmentally friendly method disclosed in this work is attractive to directly synthesize biodegradable polymeric particles with potential biomedical applications.

Synthesis, Structure, and Dispersion Property of a Novel Lignin-Based Polyoxyethylene Ether from Kraft Lignin and Poly(ethylene glycol)

In this study, a novel and water-soluble lignin-based polyoxyethylene ether (KL-PEG) was synthesized from kraft lignin (KL) and poly(ethylene glycol) (PEG). PEGs with various polyoxyethylene ether lengths were functionalized preferentially with epichlorohydrin using BF3-Et2O as the Lewis acid catalyst and then grafted onto KL by blocking the phenolic hydroxyl groups. The generated KL-PEG copolymer was purified successively by extraction, dissolution, and precipitation using butanone, alcohol, and diethyl ether, respectively. The effect of reactant ratios on the structure of the KL-PEG copolymer was investigated by Fourier transform infrared spectra (FTIR), ultraviolet spectrophotometer (UV), gel permeation chromatography (GPC), and functional groups content determination. Solubility and FTIR results revealed the successful introduction of PEG into KL. The PEG content in the KL-PEG copolymer could be controlled by varying the mass ratio of PEG to KL, and the molecular weight could be governed by the molar ...

Synthesis of polyvinyltrimethylsilane-graft-poly(ethylene glycol) copolymers and properties of gas-separating membranes formed on their basis

A method is developed for the synthesis of the graft copolymer polyvinyltrimethylsilane-graft-poly(ethylene glycol) via the interaction of a brominated polymer with the methyl ether of a low-molecular-mass poly(ethylene glycol). Graft copolymer samples containing up to 79 wt % poly(ethylene glycol) are synthesized through this method. The properties of the graft copolymers and blends formed on their basis with a specially synthesized low-molecular-mass PEG derivative with a terminal trimethylsilyl group are investigated. Physical blends are prepared in order to increase the content of ethylene oxide groups while the film-forming properties of the composite materials are preserved. As shown by structural studies, the graft copolymers are amorphous single-phase systems, while the related blends are two-phase disperse systems, in which one phase is enriched in polytrimethylvinylsilane and the other is enriched in PEG. Studies of the gas-transport behavior of the samples reveal that the introduction of PEG, in contrast to the nonselective initial polymer, results in the formation of PVTMS-based materials that are selective for CO2 in mixtures with H2.

An extremely simple method for fabricating 3D protein microarrays with an anti-fouling background and high protein capacity.

Protein microarrays have become vital tools for various applications in biomedicine and bio-analysis during the past decade. The intense requirements for a lower detection limit and industrialization in this area have resulted in a persistent pursuit to fabricate protein microarrays with a low background and high signal intensity via simple methods. Here, we report on an extremely simple strategy to create three-dimensional (3D) protein microarrays with an anti-fouling background and a high protein capacity by photo-induced surface sequential controlled/living graft polymerization developed in our lab. According to this strategy, "dormant" groups of isopropyl thioxanthone semipinacol (ITXSP) were first introduced to a polymeric substrate through ultraviolet (UV)-induced surface abstraction of hydrogen, followed by a coupling reaction. Under visible light irradiation, the ITXSP groups were photolyzed to initiate surface living graft polymerization of poly(ethylene glycol) methyl methacrylate (PEGMMA), thus introducing PEG brushes to the substrate to generate a full anti-fouling background. Due to the living nature of this graft polymerization, there were still ITXSP groups on the chain ends of the PEG brushes. Therefore, by in situ secondary living graft cross-linking copolymerization of glycidyl methacrylate (GMA) and polyethylene glycol diacrylate (PEGDA), we could finally plant height-controllable cylinder microarrays of a 3D PEG network containing reactive epoxy groups onto the PEG brushes. Through a commonly used reaction of amine and epoxy groups, the proteins could readily be covalently immobilized onto the microarrays. This delicate design aims to overcome two universal limitations in protein microarrays: a full anti-fouling background can effectively eliminate noise caused by non-specific absorption and a 3D reactive network provides a larger protein-loading capacity to improve signal intensity. The results of non-specific protein absorption tests demonstrated that the introduction of PEG brushes greatly improved the anti-fouling properties of the pristine low-density polyethylene (LDPE), for which the absorption to bovine serum albumin was reduced by 83.3%. Moreover, the 3D protein microarrays exhibited a higher protein capacity than the controls to which were attached the same protein on PGMA brushes and monolayer epoxy functional groups. The 3D protein microarrays were used to test the immunoglobulin G (IgG) concentration in human serum, suggesting that they could be used for biomedical diagnosis, which indicates that more potential bio-applications could be developed for these protein microarrays in the future.

Rapidly in situ forming adhesive hydrogel based on a PEG-maleimide modified polypeptide through Michael addition

Polyethylene glycol-maleimide modified ε-polylysine (EPL-PEG-MAL) with a unique comb-shaped structure was designed and used as a novel crosslinker for thiolated chitosan (CSS). Novel polysaccharide/polypeptide bionic hydrogels based on CSS and EPL-PEG-MAL could form rapidly in situ within 1 min via Michael addition under physiological conditions. Rheological studies showed that introduction of PEG can dramatically improve the storage modulus (G') of the hydrogels and the optimal hydrogel system showed superior G' of 1,614 Pa. The maximum adhesion strength reached 148 kPa, six times higher than that of fibrin glue. Cytotoxicity test indicated that the hydrogel is nontoxic toward growth of L929 cells. Gelation time, swelling ratio, storage modulus and adhesion strength of the hydrogels can be modulated by the content of PEG-maleimide, CSS concentration and molar ratio of maleimide group to thiol group. Benefiting from the fast gelation behaviors, desirable mechanical properties, relatively high adhesive performance and no cytotoxicity, these hydrogels have the potential applications as promising biomaterials for tissue adhesion and sealing.

Properties of Polypeptide-Based Membrane Improved by Flexible Poly(ethylene glycol)

Poly(γ-benzyl L-glutamate)/poly(ethylene glycol) (PBLG/PEG) polymer blend membranes were prepared by casting the polymer blend solution in chloroform. Surface morphologies of the polymer blend membranes were investigated by atomic force microscopy (AFM) and scanning electron microscopy (SEM). Thermal and mechanical properties of the polymer blend membranes were researched using differential scanning calorimeter (DSC) and tensile tests. It was revealed that the introduction of PEG could exert outstanding effects on the morphology and the properties of the polymer blend membranes.

Development of PEG–PLA/PLGA microparticles for pulmonary drug delivery prepared by a novel emulsification technique assisted with amphiphilic block copolymers

We developed a novel "spray dry-based" method for preparing surface-modified particle via "block copolymer-assisted" emulsification/evaporation for pulmonary drug delivery. The method included three steps: (1) o/w emulsion containing both hydrophobic polymers and amphiphilic block copolymers was obtained by emulsification of water and a polymer-containing organic solvent, (2) the o/w emulsion was misted with a nebulizer, and (3) the emulsion mists were dried by a heater. In this way, the hydrophobic polymers and the hydrophobic part of the amphiphilic block copolymers gradually tangled during the evaporation of organic solvents from the o/w emulsion. Consequently, the hydrophilic polymer chain was introduced on the particle surface. The particle surface can be easily modified although there are no reactive groups in the hydrophobic polymer molecules. We successfully obtained dry PEG-PLA/PLGA microparticles by controlling the weight ratio of the block copolymer and the hydrophobic polymer. The introduction of PEG to the particle surface involves an increase in the Zeta potential of the particles. Interestingly, the "dimpled" microparticles having a diameter of approximately 2 μm were obtained. The "dimpled" microparticles can serve as drug carriers for pulmonary drug delivery, because the particles have a large surface area. We expect that this novel surface-modification technique will enable efficient fabrication of particles in drug delivery systems.

Novel one-pot facile technique for preparing nanoparticles modified with hydrophilic polymers on the surface via block polymer-assisted emulsification/evaporation process

In this paper, we describe the novel facile technique for preparing surface-modified nanoparticles via newly developed amphiphilic block polymer-assisted emulsification/evaporation process. The effects of both organic solvents (the dispersed phase) and stabilizer in the external continuous phase on the stability of o/w emulsion was firstly investigated to clarify the optimal conditions for stable emulsification/evaporation processes. We found that the organic solvent mixture having a density adjusted to be 1.00 g/cm 3 gave the highly stable o/w emulsion. Under the optimal conditions, the relatively monodisperse poly(ethylene glycol) (PEG)–modified poly(lactide- co-glycolide) (PLGA) nanoparticle was obtained and characterized. The introduction of PEG to the particle surface was suggested by the fact that the diameter and zeta potential of the particle increased as the amount of added block polymer increased. The facile method presented in this paper can be a universal tool for modifying the surface of nanoparticles, even though reactive groups are not present on the surface.

ELECTROCHEMICAL POLYMERIZATION OF ACENAPHTHENE IN BORON TRIFLUORIDE DIETHYL ETHERATE CONTAINING POLYETHYLENE GLYCOL OLIGOMERS

A novel dark brown polyacenaphthene film has been electrodeposited on platinum electrode by direct anodic oxidation of acenaphthene in mixed electrolyte of boron triflouride diethyl etherate(BFEE) and polyethylene glycol oligomers with a molecular weight of 400(PEG 400).The oxidation potential of acenaphthene in this medium was initiated at approximately 0.95 V versus SCE,which was much lower than that determined in acetonitrile containing 0.1 mol\5L~(1) Bu_4NBF_4(1.38 V versus SCE).The introduction of PEG 400 improved the solubility of the monomer in the mixed electrolytes.The structure of the polymer was investigated by UV-Vis,FTIR and()~1H-NMR.Fluorescent spectral studies indicated that polyacenaphthene film was a blue light emitter both in DMSO solutions and in solidstate.

Preparation and spectroscopic characterization of methoxy poly(ethylene glycol)-grafted water-soluble chitosan

The object of this study was to test the solubility of a methoxy poly(ethylene glycol) (MPEG)-grafted chitosan copolymer in organic solvents and aqueous solution. Water-soluble chitosan with low molecular weight (LMWSC) was used in a PEG-graft copolymerization. The MPEG was conjugated to chitosan using 4-dicyclohexylcarbodimide (DCC), and N-hydroxysuccimide (NHS). Introduction of PEG was confirmed by 1H and 13C NMR spectroscopy and FT-IR spectroscopy. The degree of substitution (DS) of MPEG into chitosan was calculated from 1H NMR data and also by estimating the molecular weight (MW) using gel permeation chromatography (GPC). The DS values obtained from 1H NMR spectroscopy and GPC were similar, indicating that MPEG-grafted LMWSC was synthesized and properly characterized. Furthermore, the introduction of PEG into chitosan increases the solubility in aqueous solutions over a range of pH values (4.0–11.0) and organic solvents such as DMF, DMSO, ethanol, and acetone.

Self-assembled patterns obtained with evaporated polymer solutions and pre-stretched polymer substrates

We report patterns comprising non-spherical microscopic pores obtained under dewetting of polymer solutions of chlorinated solvents and amorphous polymers deposited on the pre-stretched polyethylene substrates. Patterns on meso- and microscopic scales were observed. Mesoscopically scaled pattern is practically insensitive to the mechanical strain, whereas small scale microscopic voids were highly deformed, and demonstrated the average eccentricity as high as 0.25. Introduction of PEG and RTV polyorganosiloxanes/silanes destroyed the large scale pattern, thus honeycomb pattern comprising non-spherical microscopic pores has been obtained. The patterns demonstrate a potential for polymer ferroelectret applications.

SPS Adsorption and Desorption during Copper Electrodeposition and Its Impact on PEG Adsorption

The adsorption and activation of bis (3-sulfopropyl)-disulfide (SPS) has been studied using a microfluidic electrochemical device. The device provides for accurate transitioning of solution over the working electrode allowing for addition or removal of additives from a base plating electrolyte. The transition from a plating bath to a polyethylene glycol bath shows a quick suppression of copper deposition similar to that seen with a bath. Acceleration at longer times, presumably by the activation of adsorbed SPS species, is a function of SPS concentration and applied cathodic potential. When copper is plated in the presence of SPS and for times around before the introduction of PEG, the activated SPS appears to inhibit the adsorption of PEG to the surface. System response to chloride ion addition or removal is relatively fast. Desorption of an activated layer occurs slowly, even at high cathodic potentials of , where current densities are over . Numerical simulations show that the time needed for PEG to saturate the bottom of a sub- feature is small relative to SPS activation times.

Investigation on the properties of methoxy poly(ethylene glycol)/chitosan graft co-polymers

Methoxy poly(ethylene glycol)/chitosan graft co-polymers (CS-g-mPEGs) with different degrees of substitution were synthesized by reductive N-alkylation of chitosan with poly(ethylene glycol) aldehyde. The crystalline and thermal properties of CS-g-mPEGs were characterized by wide-angle X-ray diffraction (XRD), differential scanning calorimetry (DSC) and thermogravimetry (TG). The results indicate that CS-g-mPEG solids represent microphase separation morphology with mPEG crystal and CS domains coexistence and the introduction of PEG on CS improves the thermal decomposition. The hydrodynamic behavior of CS-g-mPEGs in aqueous solution and the influence of NaCl were investigated. The results indicate that the hydrodynamic behavior of CS-g-mPEGs in aqueous solution is significantly affected by the degree of substitution and the concentration of NaCl, which are quite different from that of CS. The results of this paper also certify that CS-g-mPEGs keep the property of complexation with a counter-ion, such as tripolyphosphate, to form nanoparticles through the electrostatic interaction.

Structural characterization and mass transfer properties of segmented polyurethane: influence of block length of hydrophilic segments

AbstractAn attempt has been made to investigate the effect of the block length of hydrophilic segments on the structure and mass transfer properties of segmented polyurethane (HSPU). Three different block lengths of hydrophilic poly(ethylene glycol) (PEG) segments were used, namely PEG‐200, PEG‐2000 and PEG‐3400, where the numbers indicate the molecular weight of the PEG in g mol−1. The HSPU were characterized using Fourier‐transform infrared (FTIR) spectroscopy, wide‐angle X‐ray diffraction (WAXD), differential scanning calorimetry (DSC), dynamic mechanical thermal analysis (DMTA) and tensile testing. Mass transfer properties were measured by sorption and water vapour flux (WVF) measurements. The control sample polyurethanes without PEG and a sample with PEG‐200 showed amorphous structure and an unclear phase separation as detected by WAXD, DSC and DMTA. There is evidence that the introduction of PEG blocks into the polyurethane matrix aids soft‐segment crystallization. The percentage crystallinity of soft segments was the highest with PEG‐2000 and an increase of PEG block length to 3400 g mol−1 resulted in a decrease in crystallinity. Mechanically, polyurethane without PEG is tough while percentage strain at maximum load increased with increasing block length of PEG. In addition, sorption and WVF increased linearly with increasing PEG block length and with temperature. The permeability of such HSPUs is a function of temperature and showed a good fit to an Arrhenius form. Copyright © 2005 Society of Chemical Industry

Preparation of PEG-grafted silica particles using emulsion method

Low-molecular-weight poly(ethylene glycol) (PEG) was grafted onto the surface of silica particles by a two-step addition process. To prepare PEG-grafted silica particles, PEGME–IPTES monomers were synthesized by the reaction of 3-(triethoxysilyl)propyl isocyanate (IPTES) with poly(ethylene glycol) methyl ether (PEGME) in the presence of dibutyltin dilaurate. To remove PEGME residues, excessive IPTES was added to the solution. The peak for a urethane carbonyl group of PEGME–IPTES was observed at 1722 cm −1 by FT-IR spectroscopy. Through the sequential addition of TEOS and PEGME–IPTES monomers, PEG was introduced onto the surface of silica particles. The introduction of PEG onto the surface was observed by SEM, Brunauer–Emmett–Teller (BET), and FT-IR spectroscopy. When PEG was grafted onto the surface of silica particles, the surface area of silica particles decreased and the average pore diameter increased. The peak for urethane carbonyl group and alkyl group of PEG appeared at 1722 cm −1 and 2920 cm −1.

PAMAM-PEG-PAMAM: Novel Triblock Copolymer as a Biocompatible and Efficient Gene Delivery Carrier

A novel triblock copolymer, PAMAM-block-PEG-block-PAMAM was synthesized and applied as a gene carrier. PAMAM dendrimer is proven to be an efficient gene carrier itself, but it is associated with certain problems such as low water solubility and considerable cytotoxicity. Therefore, we introduced PEG to engineer a nontoxic and highly transfection efficient polymeric gene carrier because PEG is known to convey water-solubility and biocompatibility to the conjugated copolymer. This copolymer could achieve self-assembly with plasmid DNA, forming compact nanosized particles with a narrow size distribution. Fulfilling our expectations, the copolymer was found to form highly water-soluble polyplexes with plasmid DNA, showed little cytotoxicity despite its poor degradability, and finally achieved high transfection efficiency comparable to PEI in 293 cells. Consequently, these data show that an approach involving the introduction of PEG to create a tree-like cationic copolymer possesses a great potential for use in gene delivery systems.

Sol–gel preparation of poly(ethylene glycol) doped indium tin oxide thin films for sensing applications

Indium tin oxide (ITO) thin films were deposited on glass or oxidized silicon substrates by sol–gel process. The sol was prepared by mixing the anhydrous indium trichloride in acetylacetone and tin (IV) chloride in ethanol. Ten percent by weight Sn-doped indium oxide (ITO) films with variation of the amount of polymer poly(ethylene glycol), PEG, added as additives were prepared by heat treatment in air at different temperature and different time intervals. The morphological, structural, optical, and electrical properties of the resulted ITO films were investigated. X-ray diffraction (XRD) results showed that the introduction of PEG lowered the intensity peaks as compared to that of the undoped ones. The SEM and AFM investigations indicated that the PEG doped thin films also result in a flatter surface compared to the undoped. The electrical and optical testings revealed that the doping of PEG could lead to increased optical transmittance rate (∼3% to 5%) with wavelength 350–700 nm and decreased sheet resistance. The ITO thin films prepared under low temperature had been employed as gas sensitive material for poisonous gas detection.