Incorporation Of Polyethylene Glycol Research Articles

Pyridinium based dicationic ionic liquids as base lubricants or lubricant additives

A series of eight new dicationic ionic liquids incorporating polyethylene glycol chains linking two N-alkylpyridinium moieties through rings position 2, were synthesized and investigated for their potential use as lubricants or lubricant additives. Alkylsulfate and bis(trifluoromethanesulfonyl)imide [NTf2] were selected as anions. Dicationic ionic liquids containing [NTf2] anion demonstrated good properties as neat lubricants showing low coefficient of friction and wear comparable with the reference lubricant (glycerol). Even more interesting could be their use as friction modifier additives since an important decrease in the coefficient of friction was achieved with a really low concentration of ionic liquid. The thermal analysis of all ionic liquids by thermal gravimetric analysis (TGA) and differential scanning calorimetry (DSC) is also described.

Microstructured porous ZnO thin film for increased light scattering and improved efficiency in inverted organic photovoltaics.

Microstructured porous zinc oxide (ZnO) thin film was developed and demonstrated as an electron selective layer for enhancing light scattering and efficiency in inverted organic photovoltaics. High degree of porosity was induced and controlled in the ZnO layer by incorporation of polyethylene glycol (PEG) organic template. Scanning electron microscopy, contact angle and absorption measurements prove that the ZnO:PEG ratio of 4:1 is optimal for the best performance of porous ZnO. Ensuring sufficient pore-filling, the use of porous ZnO leads to a marked improvement in device performance compared to non-porous ZnO, with 35% increase in current density and 30% increase in efficiency. Haze factor studies indicate that the performance improvement can be primarily attributed to the improved light scattering enabled by such a highly porous structure.

Heat induced evaporative antisolvent nanoprecipitation (HIEAN) of itraconazole.

Itraconazole (ITR) is an antifungal drug with a limited bioavailability due to its poor aqueous solubility. In this study, ITR was used to investigate the impact of nanonisation and solid state change on drug's apparent solubility and dissolution. A bottom up approach to the production of amorphous ITR nanoparticles (NPs), composed of 100% drug, with a particle diameter below 250 nm, using heat induced evaporative antisolvent nanoprecipitation (HIEAN) from acetone was developed. The NPs demonstrated improved solubility and dissolution in simulated gastro-intestinal conditions when compared to amorphous ITR microparticles. The incorporation of polyethylene glycol (PEG) or its methoxylated derivative (MPEG) as a stabiliser enabled the production of smaller NPs with narrower particle size distribution and enhanced apparent solubility. MPEG stabilised NPs gave the greatest ITR supersaturation levels (up to 11.6±0.5 μg/ml) in simulated gastric fluids. The stabilising polymer was in an amorphous state. Dynamic vapour sorption data indicated no solid state changes in NP samples with water vapour at 25 °C, while crystallisation was apparent at 50 °C. HIEAN proved to be an efficient method of production of amorphous ITR NPs, with or without addition of a polymeric stabiliser, with enhanced pharmaceutical properties.

Polyvinylidene fluoride and polyetherimide hollow fiber membranes for CO2 stripping in membrane contactor

Porous polyvinylidene fluoride (PVDF) and polyetherimide (PEI) hollow fiber membranes incorporating polyethylene glycol (PEG) were prepared via spinning process for CO2 membrane stripping. CO2 loaded diethanolamine solution was used as liquid absorbent while N2 was used as a strip gas. The characterization study of the fibers was carried out in terms of permeation test, contact angle measurement and liquid entry pressure (wetting pressure). Performance study via membrane contactor stripping was carried out at specific operating condition. The experimental results showed that PVDF membrane have high gas permeation, effective surface porosity and contact angle despite having lower liquid entry pressure in comparison with PEI membrane. PVDF-PEG membrane showed the highest stripping flux of 4.0×10−2molm−2s−1 at 0.7ms−1 compared to that of PEI membrane. Although the stripping flux for PEI-PEG membranes was slightly lower than PVDF membrane (e.g. 3.5×10−2molm−2s−1 at liquid velocity of 0.85ms−1), the membrane wetting pressure of PEI membrane is higher than hydrophobic PVDF membrane. Long term performance of both membranes showed severe flux reduction but started to level-off after 30h of operation.

Effects of Multi-Walled Carbon Nanotubes (MWCNTS) on the Mechanical and Thermal Properties of Plasticized Polylactic Acid Nanocomposites

A multi-walled carbon nanotube (MWCNT)/plasticized polylactic acid (PLA) composite was prepared using a two-roll mill set at 170°C and 50 rev/min. The material was characterized using dynamic mechanical analyzer (DMA). Characterization works include obtaining mechanical properties, such as tensile and flexural properties of the nanocomposites. Polyethylene glycol (PEG) at 6 wt% was used as the plasticizer for blending with the PLA. It was found that the tensile and flexural strengths of the nanocomposites increased up to 43.8 MPa and 81.4 MPa respectively with the addition of 0.15 wt% MWCNTs. The DMA results revealed that the storage modulus and the glass transition temperature (Tg) of the nanocomposites improved with the addition of 0.15 wt% CNTs, which was previously reduced by the incorporation of PEG.

Mechanical and Flame Retardant Properties of Phenolic Foam Modified with Polyethyleneglycol as Toughening Agent

Polyethyleneglycol (PEG) was used as a as a toughening agent and mixed with the phenolic resin to prepare the foam. The effects of polyethyleneglycol on mechanical and flame retardant properties of phenolic foam were studied by compressive strength, tensile strength, heat stability, scanning electron microscopy (SEM), UL-94 and limited oxygen index (LOI). The apparent density and SEM results showed that the addition of PEG can decrease the apparent density of phenolic foam. The compressive, impact test results showed that the incorporation of PEG into PF dramatically improved the compressive strength, impact strength, indicating the excellent toughening effect of PEG. The LOI of PEG modified phenolic foams remained a high value and the UL-94 results showed all samples can pass V-0 rating, indicating the modified foams still had good flame retardance. The thermal properties of the foams were investigated by thermogravimetric analysis.

Nanocomposite liposomes containing quantum dots and anticancer drugs for bioimaging and therapeutic delivery: a comparison of cationic, PEGylated and deformable liposomes

Multifunctional liposomes loaded with quantum dots (QDs) and anticancer drugs were prepared for simultaneous bioimaging and drug delivery. Different formulations, including cationic, PEGylated and deformable liposomes, were compared for their theranostic efficiency. We had evaluated the physicochemical characteristics of these liposomes. The developed liposomes were examined using experimental platforms of cytotoxicity, cell migration, cellular uptake, in vivo melanoma imaging and drug accumulation in tumors. The average size of various nanocomposite liposomes was found to be 92–134 nm. Transmission electron microscopy confirmed the presence of QDs within liposomal bilayers. The incorporation of polyethylene glycol (PEG) and Span 20 into the liposomes greatly increased the fluidity of the bilayers. The liposomes provided sustained release of camptothecin and irinotecan. The cytotoxicity and cell migration assay demonstrated superior activity of cationic liposomes compared with other carriers. Cationic liposomes also showed a significant fluorescence signal in melanoma cells after internalization. The liposomes were intratumorally administered to a melanoma-bearing mouse. Cationic liposomes showed the brightest fluorescence in tumors, followed by classical liposomes. This signal could last for up to 24 h for cationic nanosystems. Intratumoral accumulation of camptothecin from free control was 35 nmol g−1; it could be increased to 50 nmol g−1 after loading with cationic liposomes. However, encapsulation of irinotecan into liposomes did not further increase intratumoral drug accumulation. Cationic liposomes were preferable to other liposomes as nanocarriers in both bioimaging and therapeutic approaches.

An amphiphilic degradable polymer/hydroxyapatite composite with enhanced handling characteristics promotes osteogenic gene expression in bone marrow stromal cells

Electrospun polymer/hydroxyapatite (HA) composites combining biodegradability with osteoconductivity are attractive for skeletal tissue engineering applications. However, most biodegradable polymers such as poly(lactic acid) (PLA) are hydrophobic and do not blend with adequate interfacial adhesion with HA, compromising the structural homogeneity, mechanical integrity and biological performance of the composite. To overcome this challenge, we combined a hydrophilic polyethylene glycol (PEG) block with poly(d,l-lactic acid) to improve the adhesion of the degradable polymer with HA. The amphiphilic triblock copolymer PLA–PEG–PLA (PELA) improved the stability of HA–PELA suspension at 25wt.% HA content, which was readily electrospun into HA–PELA composite scaffolds with uniform fiber dimensions. HA–PELA was highly extensible (failure strain >200% vs. <40% for HA–PLA), superhydrophilic (∼0° water contact angle vs. >100° for HA–PLA), and exhibited an 8-fold storage modulus increase (unlike deterioration for HA–PLA) upon hydration, owing to the favorable interaction between HA and PEG. HA–PELA also better promoted osteochondral lineage commitment of bone marrow stromal cells in unstimulated culture and supported far more potent osteogenic gene expression upon induction than HA–PLA. We demonstrate that the chemical incorporation of PEG is an effective strategy to improve the performance of degradable polymer/HA composites for bone tissue engineering applications.

Simultaneous Determination of Polyethylene Glycol-Conjugated Liposome Components by Using Reversed-Phase High-Performance Liquid Chromatography with UV and Evaporative Light Scattering Detection

Liposomes incorporating polyethylene glycol (PEG)-conjugated lipids (PEGylated liposomes) have attracted attention as drug delivery carriers because they show good in vivo stability. The lipid component of PEGylated liposomal formulations needs to be quantified for quality control. In this study, a simple reversed-phase high-performance liquid chromatography (HPLC) method with an evaporative light-scattering detector (ELSD) was established for simultaneous determination of hydrogenated soy phosphatidylcholine, cholesterol, PEG-conjugated lipid, and hydrolysis products of phospholipid in PEGylated liposomal formulations. These lipids were separated using a C18 column with a gradient mobile phase consisting of ammonium acetate buffer and ammonium acetate in methanol at a flow rate of 1.0 ml/min. This method provided sufficient repeatability, linearity, and recovery rate for all lipids. However, the linearity and recovery rates of cholesterol achieved using a ultraviolet (UV) detector were better than those achieved using an ELSD. This validated method can be applied to assess the composition change during the preparation process of liposomes and to quantify lipid components and hydrolysis products contained in a commercially available liposomal formulation DOXIL®. Taken together, this reversed-phase HPLC-UV/ELSD method may be useful for the rapid or routine analysis of liposomal lipid components in process development and quality control.

Tuning the mechanical properties of glass fiber-reinforced bismaleimide–triazine resin composites by constructing a flexible bridge at the interface

We demonstrate a new method that can simultaneously improve the strength and toughness of the glass fiber-reinforced bismaleimide–triazine (BT) resin composites by using polyethylene glycol (PEG) to construct a flexible bridge at the interface. The mechanical properties, including the elongation, ultimate tensile stress, Young’s modulus, toughness and dynamical mechanical properties were studied as a function of the length of PEG molecular chain. It was found that the PEG molecule acts as a bridge to link BT resin and glass fiber through covalent and non-covalent bondings, respectively, resulting in improved interfacial bonding. The incorporation of PEG produces an increase in elongation, ultimate tensile stress and toughness. The Young’s modulus and Tg were slightly reduced when the length of the PEG molecular chain was high. The elongation of the PEG-modified glass fiber-reinforced composites containing 5 wt% PEG-8000 increased by 67.1%, the ultimate tensile stress by 17.9% and the toughness by 78.2% compared to the unmodified one. This approach provides an efficient way to develop substrate material with improved strength and toughness for integrated circuit packaging applications.

Computational and Experimental Study of the Effect of PEG in the Preparation of Damascenone-Imprinted Xerogels

Macromolecules, such as polyethylene glycol (PEG), have been frequently used in the preparation of xerogels, mainly with the purpose of tuning the meso- or macroporosity. However, PEG has never been applied in the context of the preparation of molecularly imprinted xerogels for small molecules. Thus, we decided to conduct a computational and experimental study of the incorporation of PEG into formerly studied sol-gel mixtures for the preparation of damascenone-imprinted xerogels. Computationally, two types of pregelification models were studied, one representing the initial mixture (SI3/SIPA:5:3 models) and the other representing the same mixtures after considerable solvent loss (SI3/SIPA:40:1 models). The latter ones were particularly prolific in providing clear effects of the PEG. In the SI3:40:1 model (containing SI3 units of Si(3)O(3)(OH)(6) mimicking the final xerogels backbone), a prohibitive instead of a promoting effect of PEG on the template-SI3 association was observed. PEG was found to interpose the SI3 aggregates, turning them smaller and more disperse. In agreement with that, a much higher porosity and surface area were found for the corresponding xerogel prepared with PEG, while no appreciable improvement of the imprinting efficiency could be observed. In the SIPA:40:1 model (containing both SI3 and SIPA units; SIPA, Si(3)O(3)(OH)(5)C(3)H(6)NHC(6)H(5), representing the introduction of the organic functional group into the xerogel network), the interactions related to the network structuring were not significantly affected. This was due to the fact that the SIPA units themselves had a dispersive effect on the silica network; the PEG molecules were "pushed" into the aqueous/methanolic continuum, and their presence was somewhat redundant. Accordingly, both prepared SIPA-xerogels (with PEG or not) exhibited higher porosity compared to SI3-xerogels. Although the simulation results were not conclusive about the effect of PEG on the template-functional group association, experimentally it was clear that the imprinting effect was not improved with PEG.

Genetic PEGylation

Polyethylene glycol (PEG) was genetically incorporated into a polypeptide. Stop-anticodon-containing tRNAs were acylated with PEG-containing amino acids and were then translated into polypeptides corresponding to DNA sequences containing the stop codons. The molecular weights of the PEG used were 170, 500, 700, 1000, and 2000 Da, and the translation was confirmed by mass spectrometry. The PEG incorporation ratio decreased as the molecular weight of PEG increased, and PEG with a molecular weight of 1000 Da was only slightly incorporated. Although improvement is required to increase the efficiency of the process, this study demonstrates the possibility of genetic PEGylation.

Influence of polyethylene glycol on in vitro gas production profiles and microbial protein synthesis of some shrub species

The aim was to determine effects of addition of polyethylene glycol (PEG) on in vitro gas production and microbial protein synthesis of the shrub species Acacia constricta, Acacia shaffneri, Calliandra eriophylla, Condalia lycioides, Cordia parvifolia, Larrea tridentata and Mimosa biuncifera, which are commonly consumed by grazing small ruminants in semiarid regions of Mexico despite the abundance of tannins in their foliage. Three individual samples (a minimum of 10 plants of each) of each shrub species were collected from different areas and prepared for chemical and secondary metabolite analysis. In vitro evaluations for each sample of each shrub species were completed in three incubation runs in different weeks using calibrated glass syringes in a 7×2 factorial design (i.e., 7 shrub species×2 treatments with or without PEG). In vitro gas production after 24 and 96h, partitioning factor (PF), metabolizable energy (ME) content, efficiency of microbial protein synthesis (EMPS), and volatile fatty acids (VFA) were determined. A shrub species×PEG interaction (P<0.05) only occurred for some VFA, such as C3, C4, C4i and C5i, concentrations. Relative to control, addition of PEG increased (P<0.05) the concentrations of individual VFA in A. shaffneri, C. lycioides and C. parvifolia. Interactions between shrub and PEG occurred (P<0.001) for all gas production parameters (i.e., b, k, IVGP24, IVGP48). The fractional rate of gas production and IVGP24h were highest in A. constricta and lowest (P<0.001) in A. shaffneri. L. tridentata had the highest PF and C. lycioides the lowest. A. constricta had the highest ME content. Purine content and EMPS differed (shrubs×PEG; P<0.001) among shrubs. Microbial protein synthesis was highest in M. biuncifera and lowest in C. eriophylla, while total VFA were highest in C. eriophylla. Incorporation of PEG increased (P<0.001) in vitro fermentation parameters and ME content with L. tridentata and C. lycioides being the highest. PEG also promoted reductions in the EMPS and PF values. In vitro fermentation variables such as fractional rate of gas production, VFA concentrations and EMPS support the potential of A. constricta, C. parvifolia and M. biuncifera as protein and energy sources for small ruminants in semiarid regions of North Mexico. Increments in gas production in these shrub species confirmed the affinity of PEG to bind condensed tannins and reduce EMPS.

Mechanical property and in vitro biocompatibility of brushite cement modified by polyethylene glycol

Brushite (dicalcium phosphate dihydrate, DCPD) cement, owing to its high solubility in physiological condition and ability to guide new bone formation, is widely used to treat bone defects. In the present study, we have evaluated the effects of poly ethylene glycol (PEG) addition on the setting time, compressive strength and in vitro biocompatibility of brushite cement. The brushite cements were prepared by mixing β-tricalcium phosphate [β-TCP, Ca3(PO4)2] and monocalcium phosphate monohydrate [MCPM, Ca(H2PO4)2 ⋅ H2O]. PEG was introduced at 2.0 and 5.0wt% with the liquid. Introduction of PEG resulted in marginal increase in both initial and final setting time, however, significantly affected the compressive strength. Effects of PEG incorporation on in vitro biocompatibility of brushite cements were studied by using human fetal osteoblast cells (hFOB) cells. Field emission scanning electron microscope (FESEM) images and immunohistochemical analysis indicated that pure and PEG incorporated brushite cement facilitates cell adhesion, proliferation and differentiation. Fewer cells expressed vinculin protein with increased PEG content in the cement. Cell proliferation was found to decrease with increased PEG concentration while the cell differentiation increased with PEG content. Our results provide a better understanding of in vitro biocompatibility of PEG added brushite cements that can be used to customize the cement compositions based on application need.

Fabrication of polymethyl methacrylate/polysulfone/nanoceramic composites for orthopedic applications

AbstractWe report the fabrication of polymethyl methacrylate/polysulfone/nanohydroxyapatite (PMMA/PSu/nHA) and PMMA/PSu/nanotitania (PMMA/PSu/nTiO2) composites using N′N′‐methylene‐bis‐acrylamide (MBA) to crosslink PMMA and act as a blending agent. The composite was made porous by incorporating polyethylene glycol as the pore‐forming agent. The blend between PMMA and PSu was confirmed using Fourier transform infrared spectroscopy and thermogravimetric analysis (TGA). The surface morphology of the composites analyzed using scanning electronic microscopy (SEM) revealed the porous structure and the wide distribution of the fillers that were found to aggregate at higher concentrations. The maximum tensile strength observed for composites was with 5% nHA (23 MPa) and 7.5% TiO2 (30 MPa). The TGA of the composites showed better thermal stability with increase in the filler concentrations. The X‐ray diffraction analysis showed that appearance of new peaks in the blend polymers indicating a strong interaction between PMMA and PSu. The surface of the composites was coated with amoxicillin and its efficiency was examined by the Zone of Inhibition test using Streptococcus mutans. The bioactivity of the composites was evaluated by immersing them in simulated body fluid and examining their surface for the formation of calcium‐phosphate layer using SEM and EDAX. Bioactivity was found to increase with increase in filler content. The in vitro biocompatibility of the composites, evaluated using monkey kidney epithelial cells by MTT assay showed that the composites containing nHA showed better cell viability than the composites with nTiO2. The study showed that the composites with nTiO2 exhibited better strength when compared with nHA composites while the later exhibited better biocompatibility. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013

Enhancing disperse printing and ultraviolet protecting of polyester-containing fabrics via pretreatment with chitosan/polyethylene glycol/dimethylol dihydroxyethylene urea

Pretreatment of polyester-containing fabrics with chitosan, polyethylene glycol along with N-methylol crosslinking agent (Arkofix® NDW, DMDHEU) in the presence of MgCl2. 6H2O/citric acid as a mixed catalyst was carried out for enhancing their printability with disperse dyes as well as upgrading their ultraviolet-protecting properties. The results showed that the changes in the depth of the obtained prints are governed by the type of substrate, chitosan concentration and steaming conditions. On the other hand, incorporation of polyethylene glycol in the pretreatment bath results in a remarkable improvement in the depth of the post-printed fabric samples. Scanning electron microscope images showed the presence of chitosan-based deposits firmly attached to the surface of the pretreated fabric samples. The mechanism of surface modification via loading of chitosan with its amino groups along with polyethylene glycol moieties onto and/or into the finish/fabric matrix was proposed.

The plasticizer‐assisted formation of a percolating multiwalled carbon nanotube network in biodegradable poly(L‐lactide)

AbstractA plasticizer, polyethylene glycol (PEG), was used to disperse multiwalled carbon nanotubes (MWCNTs) in biodegradable poly(L‐lactide) during one‐step melt mixing. Incorporation of PEG significantly promotes the formation of a percolating MWCNT network in the plasticized composites, as revealed by rheological measurements and morphological observations. It, in turn, results in the retarded glass transition and cold crystallization behaviors in these plasticized composites as a result of constrained chain relaxation. It is believed that noncovalent wrapping of MWCNTs by PEG is responsible for the improved affinity between MWCNTs and the poly(L‐lactide) matrix. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Novel approach for preparing nontoxic stealth microspheres for drug delivery

Normal.dotm 0 0 1 124 709 Uni 5 1 870 12.0 0 false 18 pt 18 pt 0 0 false false false Polyethylene glycol 2000 (PEG) entrapped, bovine serum albumin (BSA) microspheres were prepared and optimized. These microspheres were then analyzed to understand the stealth effect to the microspheres imparted by incorporated polyethylene glycol (PEG). Microsphere preparations (formulations) were studied for particle size, zeta potential, free BSA content, and in-vitro uptake by human micro-vascular endothelial cells (HMECs). The results demonstrate, a formulation containing 37.5 % PEG (w/w) exhibits an acceptable particle size of &lt;5 µm, good suspendibility with zeta potential of -35 mV, and confers some degree of stealth property to the microspheres. These non-toxic, biodegradable and long circulating microspheres have the potential to be used for extended intravenous (IV) drug delivery. Statistical analysis done by ANOVA and results with p&lt;0.05 were considered significant.

Physicochemical and drug diffusion analysis of rifampicin containing polyethylene glycol–poly(ɛ-caprolactone) networks designed for medical device applications

This study reports the physicochemical and drug diffusion properties of rifampicin containing poly(ɛ-caprolactone) (PCL)/polyethylene glycol (PEG) networks, designed as bioactive biomaterials. Uniquely, the effects of the states of both rifampicin and PEG and the interplay between these components on these properties are described. PCL matrices containing rifampicin (1–5%, w/w) and PEG 200 (0–15%, w/w) were prepared by casting from an organic solvent (dichloromethane). The films were subsequently characterized in terms of their thermal/thermorheological, surface and tensile properties, biodegradation and drug diffusion/release properties. Incorporation of PEG and/or rifampicin significantly affected the tensile and surface properties of PCL, lowering the ultimate tensile strength, % elongation at break, Young modulus and storage and loss moduli. Both in the absence and presence of PEG, solubilisation of rifampicin within the crystalline domains of PCL was observed. PEG was present as a dispersed liquid phase. The release of rifampicin (3% loading) was unaffected by the presence of PEG. Similarly the release of rifampicin (5%) was unaffected by low concentrations of PEG (5–10%) however, at higher loadings, the release rate of rifampicin was enhanced by the presence of PEG. Rifampicin release (10% loading) was enhanced by the presence of PEG in a concentration dependent fashion. These observations were accredited to enhanced porosity of the matrix. In all cases, diffusion-controlled release of rifampicin occurred which was unaffected by polymer degradation. This study has uniquely illustrated the effect of hydrophilic pore formers on the physicochemical properties of PCL. Interestingly, enhanced diffusion controlled release was only observed from biomaterials containing high loadings of PEG and rifampicin (5, 10%), concentrations that were shown to affect the mechanical properties of the biomaterials. Care should therefore be shown when adopting this strategy to enhance release of bioactive agents from biomaterials.

Au/SnO2 an excellent material for room temperature carbon monoxide sensing

Tin dioxide synthesized by the hydrothermal method, impregnated with Au has been used for the room temperature carbon monoxide sensing in air. Incorporation of poly ethylene glycol (PEG-6000) as a modifier during the synthesis procedure results in well dispersed nanosized particles of SnO2 which influence the sensing capability dramatically. This tailored morphology leads to development of a material with improved sensor response. Incorporation of gold resulted in a composition that was capable of selectively sensing low concentrations (upto 10ppm CO in air) at temperatures below 50°C. The mechanism of improved sensing has been explained based on the gas sensing characteristics with support from TEM, UV-DRS, XPS and FTIR.