Different Molecular Weights Of Polyethylene Glycol Research Articles

Effect of different molecular weight polyethylene glycol on flat sheet cellulose acetate membranes for evaluating power density performance in pressure retarded osmosis study

In this study, different molecular weights of polyethylene glycol (PEG) (Mw = 4000 and 6000 g/mole) were used as additives for preparations of modified cellulose acetate (CA) flat asymmetric membranes. The effects of additives on membrane characteristics and power density were investigated using the reverse osmosis and pressure retarded osmosis (PRO) methods Membrane characterization and power density of the fabricated membranes were evaluated using the PRO setup. The results show enhancement in the performance of membranes in terms of power density that can be extracted from the membranes with various additives. Furthermore, a comparison was made on the power density obtained using different molecular weights of PEG with CA as a base polymer. A power density of 0.7 W/m2 was obtained from the unmodified CA membrane, which increased to 2.7 W/m2 and 3.1 W/m2 for the modified membranes with PEG 4000 and 6000, respectively. The enhanced power density was due to the better membrane characteristics with respect to its hydrophilicity, pure water flux (PWF), salt rejection and porosity. Therefore, this study provides deeper insights on the performance of membranes with higher molecular weight PEG to get better power density values and attests importance of similar studies in energy science.

Effect of different organic salts on amino acids partition behaviour in PEG-salt ATPS

The phase diagrams of six different polyethylene glycol (PEG)–salt aqueous two-phase systems (ATPS) were measured at T = 298.15 K and p = 1 bar. PEG of different molecular weight (4000, 6000 and 8000) and organic salts (potassium citrate, potassium sodium tartrate) were used to form the biphasic systems. The results were compared with data for PEG–sodium citrate ATPS, reported in the literature (PEG 4000, PEG 6000) and measured in this work (PEG 8000). The partition of four dinitrophenyl-amino acids was measured in these ATPS for different tie-line lengths. Based on these data, cation and anion effects were evaluated in terms of the relative hydrophobicity of the phases using ΔG*(CH2) calculations. The distribution coefficients have been obtained spectrophotometrically. Studies on the partitioning indicate the advantage of citrate salts over tartrate salts as well as sodium-based salts over potassium-based salts. This consistently results from the (liquid-liquid) phase behaviour of these systems.

Triple-component nanocomposite films prepared using a casting method: Its potential in drug delivery

The purpose of this study was to fabricate a triple-component nanocomposite system consisting of chitosan, polyethylene glycol (PEG), and drug for assessing the application of chitosan–PEG nanocomposites in drug delivery and also to assess the effect of different molecular weights of PEG on nanocomposite characteristics. The casting/solvent evaporation method was used to prepare chitosan–PEG nanocomposite films incorporating piroxicam-β-cyclodextrin. In order to characterize the morphology and structure of nanocomposites, X-ray diffraction technique, scanning electron microscopy, thermogravimetric analysis, and Fourier transmission infrared spectroscopy were used. Drug content uniformity test, swelling studies, water content, erosion studies, dissolution studies, and anti-inflammatory activity were also performed. The permeation studies across rat skin were also performed on nanocomposite films using Franz diffusion cell. The release behavior of films was found to be sensitive to pH and ionic strength of release medium. The maximum swelling ratio and water content was found in HCl buffer pH 1.2 as compared to acetate buffer of pH 4.5 and phosphate buffer pH 7.4. The release rate constants obtained from kinetic modeling and flux values of ex vivo permeation studies showed that release of piroxicam-β-cyclodextrin increased with an increase in concentration of PEG. The formulation F10 containing 75% concentration of PEG showed the highest swelling ratio (3.42±0.02) in HCl buffer pH 1.2, water content (47.89±1.53%) in HCl buffer pH 1.2, maximum cumulative drug permeation through rat skin (2405.15±10.97 μg/cm2) in phosphate buffer pH 7.4, and in vitro drug release (35.51±0.26%) in sequential pH change mediums, and showed a significantly (p<0.0001) higher anti-inflammatory effect (0.4 cm). It can be concluded from the results that film composition had a particular impact on drug release properties. The different molecular weights of PEG have a strong influence on swelling, drug release, and permeation rate. The developed films can act as successful drug delivery approach for localized drug delivery through the skin.

Influence of the Molecular Weight of PEG on the Polymer/Salt Phase Diagrams of Aqueous Two-Phase Systems

Binodal data for systems composed by polyethylene glycol (PEG) (4000, 6000, or 8000) and salt (potassium citrate, potassium sodium tartrate) were obtained using the cloud point method, at T = 298.15 K. Merchuk equation was applied for the fitting of binodal curves. Tie-lines for systems of PEG (4000, 6000)–potassium citrate and PEG (4000, 6000, 8000)–potassium sodium tartrate were determined by electrical conductivity and lyophilization, and correlated using Othmer–Tobias and Bancroft equations, to verify the reliability of the measured tie-lines. Data were compared with that of previous studies reported in the literature, giving an indication of which system is more efficient in terms of separation, taking into account possible combinations of salt’s cations and PEGs of different molecular weight chosen for ATPS.

Impact of synthesized amino alcohol plasticizer on the morphology and hydrophilicity of polysulfone ultrafiltration membrane

In this work, polysulfone (PSF) ultrafiltration membranes with increased hydrophilicity were prepared using the amino alcohol plasticizer (AAP). The AAP was synthesized by the reaction of polyethylene glycol (PEG) and isatoic anhydride (IAH). Different molecular weight of PEG and IAH (molecular weight 163Da) were used for preparing the AAP. Asymmetric membranes were fabricated by blending these plasticizers in membrane casting solution. Formation of AAP was confirmed by FTIR and 1HNMR spectra of AAP. Characterization of membranes was done in terms of hydraulic permeability, pure water flux (PWF) and hydrophilicity. PWF was found to be increased from 29.3L/m2h to 110.1L/m2h and water contact angle also reduced from 72° to 62° for plain and AAP containing PSF membrane, respectively. The morphological and structural analysis of the membranes was done by scanning electron microscope and field emission scanning electron microscope. Permeation and rejection behavior of fabricated membranes was studied by Bovine serum albumin (BSA) solution. Maximum BSA rejection was increased by 20.5% for the modified membrane. FESEM images affirm that the pore size of the membranes decreased by the addition of AAP. PEG with molecular weight of 400Da based AAP gave best performance among all the membranes for each parameter.

The Effect of PEGylation on Multivalent Binding: A Surface Plasmon Resonance and Isothermal Titration Calorimetry Study with Structurally Diverse PEG‐Dendritic GATG Copolymers

AbstractA general synthetic strategy to polyethylene glycol (PEG)‐dendritic block copolymers of the GATG (gallic acid–triethylene glycol) family is described from commercially available PEG of different molecular weights and architectures. Glycosylation of the resulting azide‐terminated copolymers with fucose by copper‐catalyzed azide–alkyne cycloaddition (CuAAC) afforded a toolbox to study the effect of PEG on the multivalent binding with the lectin UEA‐I by surface plasmon resonance (SPR, on surface) and isothermal titration calorimetry (ITC, in solution). Our results indicate that PEG reduces the affinity of glycodendrimers towards lectins by steric hindrance in a molecular‐weight‐dependent fashion. Great differences were observed as a function of the PEG architecture, with diblock PEG‐dendritic copolymers benefiting from a positive entropic contribution (PEG folding), not seen in the dendritic‐PEG‐dendritic systems. The self‐inflicted steric stabilization of the PEGylated copolymers onto lectin clusters reveals the necessity of additional competitive experiments to fully assess the antiadhesive properties of PEG in biological environments.

Aqueous two-phase (polyethylene glycol + sodium sulfate) system for caffeine extraction: Equilibrium diagrams and partitioning study

Environmental friendly methods for liquid–liquid extraction have been taken into account due to critical conditions and ecotoxicological effects potentially produced by organic solvents applied in traditional methods. Liquid–liquid extraction using aqueous two phase systems (ATPSs) presents advantages when compared to traditional liquid–liquid extraction. (Polyethylene glycol (PEG)+sodium sulfate+water) ATPS was applied to study partition of caffeine. Binodal curves for ATPSs composed of PEG of different molecular weights (400g·mol−1, 4000g·mol−1 and 6000g·mol−1) sodium sulfate+water were determined by cloud point method at three different temperatures (293.15, 313.15 and 333.15)K. Liquid–liquid equilibrium (LLE) data (tie-lines, slope of the tie-line and tie-lines length) were obtained applying a gravimetric method proposed by Merchuck and co-workers at the same temperatures for aqueous (PEG 400+sodium sulfate) and aqueous (PEG 400+sodium sulfate+caffeine) systems. Reliability of the experimental tie-line (TL) data was evaluated using the equations reported by Othmer–Tobias and satisfactory linearity was obtained. Concerning to aqueous (PEG+sodium sulfate) system, the results pointed out that the higher PEG molecular weight the largest is the heterogeneous region. Moreover, temperature showed not to be relevant on binodal curves behavior, but it influenced on tie-line slopes. Partitioning of caffeine in aqueous (PEG 400+sodium sulfate) system was investigated at different temperatures and tie-lines lengths (TLLs). It was shown that the partitioning was depended on the temperature and TLL and at all conditions studied the salting out effect displayed higher influence leading caffeine partition preferentially into the PEG rich (top) phase.

Polyethylene glycols: An effective strategy for limiting liver ischemia reperfusion injury.

Liver ischemia-reperfusion injury (IRI) is an inherent feature of liver surgery and liver transplantation in which damage to a hypoxic organ (ischemia) is exacerbated following the return of oxygen delivery (reperfusion). IRI is a major cause of primary non-function after transplantation and may lead to graft rejection, regardless of immunological considerations. The immediate response involves the disruption of cellular mitochondrial oxidative phosphorylation and the accumulation of metabolic intermediates during the ischemic period, and oxidative stress during blood flow restoration. Moreover, a complex cascade of inflammatory mediators is generated during reperfusion, contributing to the extension of the damage and finally to organ failure. A variety of pharmacological interventions (antioxidants, anti-cytokines, etc.) have been proposed to alleviate graft injury but their usefulness is limited by the local and specific action of the drugs and by their potential undesirable toxic effects. Polyethylene glycols (PEGs), which are non-toxic water-soluble compounds approved by the FDA, have been widely used as a vehicle or a base in food, cosmetics and pharmaceuticals, and also as adjuvants for ameliorating drug pharmacokinetics. Some PEGs are also currently used as additives in organ preservation solutions prior to transplantation in order to limit the damage associated with cold ischemia reperfusion. More recently, the administration of PEGs of different molecular weights by intravenous injection has emerged as a new therapeutic tool to protect liver grafts from IRI. In this review, we summarize the current knowledge concerning the use of PEGs as a useful target for limiting liver IRI.

Stabilization of Chromobacterium viscosum Lipase (CVL) Against Ultrasound Inactivation by the Pretreatment with Polyethylene Glycol (PEG).

Although ultrasound has been used to accelerate many enzymatic reactions, the low stability of enzymes in such a system still remains a critical issue, limiting its industrial application. Here, we have reported that polyethylene glycol (PEG) pretreatment stabilized Chromobacterium viscosum lipase (CVL) in ultrasound-assisted water-isooctane emulsion. PEGs of different molecular weights and concentrations were used to pretreat CVL, and the pretreated lipase activities for olive oil hydrolysis were investigated at different ultrasonic powers. The best result was attained with PEG400 at 100mg/ml for a lipase concentration of 0.02mg/ml and an ultrasonic power of 106W. The half-life time of PEG400-treated lipase at 106W was 54min, a 27-fold higher than that attained using untreated lipase. Circular dichroism (CD) spectra suggested that PEG increased the rigidity of CVL structure, which favored the lipase stability against ultrasound inactivation. These results have important implications for the exploitation of ultrasound in biocatalytic process.

Some Physical Properties of &lt;i&gt;Vernonia amygdalina&lt;/i&gt; and &lt;i&gt;Garcinia kola&lt;/i&gt; Microspheres Prepared with High Molecular Weight Polyethylene Glycols

The effect of polymer concentrations on some of the physicochemical properties of Vernonia amygdalina (Linn) and Garcinia kola (Heckel) extracts loaded microspheres was evaluated. Microspheres of the aqueous extracts was prepared by emulsion solvent evaporation using polyethylene glycol (PEG) mixtures of molecular weight 4000 and 6000 at different ratios of 1:0, 0:1, 1:1, 1:2 and 2:1 while the amounts of the extracts incorporated was constant for all ratios. The microspheres were evaluated for their particles sizes, yield, flavonoid content, loading efficiency, moisture loss and flow properties. In-vitro release studies were carried out by monitoring flavonoid release rate from the microspheres. The microspheres were spherical and uniformly shaped and exhibited good flow characteristics. Their size range, yield, loading efficiency, moisture loss and flavonoid content were 76 - 83 im, 49 - 76 %, 47 - 82 %, 2.18 - 4.60 % and 17.10 - 23.80 mg%, respectively for V. amygdalina and 144 - 160 im, 50 - 68 %, 51 - 68 %, 3.00 - 4.41 % and 20.00 - 28.70 mg%, respectively for G. kola . Flavonoids release from the microsphere was up to 90 % within 1 h and it followed a matrix release kinetic model with a super case-II transport mechanism. The concentrations of the polymers affected the yield, loading efficiency, moisture loss and the extent of flavonoid release of the microspheres but had no effect on their particle sizes and flavonoid content. These results may find useful application in the delivery of V. amygdalina and G. kola extracts since the combination of PEG of different molecular weights resulted in microspheres with good physicochemical and release properties. © JASEM

Size Controlled Synthesis of CoFe2O4 Nanoparticles with Polyethylene Glycol

Nanoparticles (NPs) of CoFe2O4, which is a well-known spinel ferrite and hard magnetic material with very high cubic magnetocrystalline anisotropy, were synthesized by co-precipitation method. The effect of different molecular weights of polyethyleneglycol (PEG) on the magnetic properties and crystallite size of CoFe2O4 NPs was investigated by using PEG-400, PEG-10.000 and, PEG-20.000. Crystalline structure and size of CoFe2O4 NPs were studied using X-ray diffraction (XRD). The VSM studies showed that the saturation magnetization (M s ) and coercivity (H c ) of the CoFe2O4 NPs depend on molecular weight of PEG.

Molecular features determining different partitioning patterns of papain and bromelain in aqueous two-phase systems

The partitioning patterns of papain (PAP) and bromelain (BR), two well-known cysteine-proteases, in polyethyleneglycol/sodium citrate aqueous two-phase systems (ATPSs) were determined. Polyethyleneglycols of different molecular weight (600, 1000, 2000, 4600 and 8000) were assayed. Thermodynamic characterization of partitioning process, spectroscopy measurements and computational calculations of protein surface properties were also carried out in order to explain their differential partitioning behavior. PAP was observed to be displaced to the salt-enriched phase in all the assayed systems with partition coefficients (KpPAP) values between 0.2 and 0.9, while BR exhibited a high affinity for the polymer phase in systems formed by PEGs of low molecular weight (600 and 1000) with partition coefficients (KpBR) values close to 3. KpBR values resulted higher than KpPAP in all the cases. This difference could be assigned neither to the charge nor to the size of the partitioned biomolecules since PAP and BR possess similar molecular weight (23,000) and isoelectric point (9.60). The presence of highly exposed tryptophans and positively charged residues (Lys, Arg and His) in BR molecule would be responsible for a charge transfer interaction between PEG and the protein and, therefore, the uneven distribution of BR in these systems.

Synthesis and Characterization of Fluorescent, Nonionic, Water Self-Dispersible Oligothiophenes

Two α-septithiophenes substituted at the third position of the middle ring with polyethyleneglycol of different molecular weights (PEG 1000 and PEG 2000) were synthesized using Suzuki condensation. Their structural characterization was performed by 1H NMR and FT-IR. The thermal behavior of the new synthesized oligothiophenes was investigated by differential scanning calorimetry (DSC) and thermogravimetrical (TGA) analysis. Photophysical properties in solutions were evaluated by UV-vis and fluorescence measurements using different solvents. The amphiphilic nature of the synthesized oligothiophenes and the presence of the PEG side chains induced self-dispersibility in water and the possibility of fluorescent nanoparticles forming by self-assembling. The size of nanoparticles in water was assessed by DLS and AFM investigations.

Improvement of Nanometer TiO&lt;sub&gt;2&lt;/sub&gt; Anti-Ultraviolet Finishing Performance for Cotton Fabric by Using Polyethylene Glycol

Cotton fabric is processed for anti-ultraviolet finishing by using nanometer TiO2 of different crystalline structures, polyethylene glycol (PEG) and so on. The results show: under the same conditions, the adhesion amount of rutile nanometer TiO2 is more than anatase nanometer TiO2; with different TiO2/PEG concentrations and different molecular weight of PEG, the adhesion amount of TiO2 is different, furthermore both the laundry-resistant property and the photoaging property have different change.

Adsorption of peptides and small proteins with control access polymer permeation to affinity binding sites. Part I: Polymer permeation-immobilized metal ion affinity chromatography separation adsorbents with polyethylene glycol and immobilized metal ions

Despite the many efforts to develop efficient protein purification techniques, the isolation of peptides and small proteins on a larger than analytical scale remains a significant challenge. Recovery of small biomolecules from diluted complex biological mixtures, such as human serum, employing porous adsorbents is a difficult task mainly due to the presence of concentrated large biomolecules that can add undesired effects in the system such as blocking of adsorbent pores, impairing diffusion of small molecules, or competition for adsorption sites. Adsorption and size exclusion chromatography (AdSEC) controlled access media, using polyethylene glycol (PEG) as a semi-permeable barrier on a polysaccharide matrix, have been developed and explored in this work to overcome such effects and to preferentially adsorb small molecules while rejecting large ones. In the first part of this work, adsorption studies were performed with small peptides and proteins from synthetic mixtures using controlled access polymer permeation adsorption (CAPPA) media created by effectively grafting PEG on an immobilized metal affinity chromatography (IMAC) agarose resin, where chelating agents and immobilized metal ions were used as the primary affinity binding sites. Synthetic mixtures consisted of bovine serum albumin (BSA) with small proteins, peptides, amino acids (such as histidine or Val4-Angiotensin III), and small molecules-spiked human serum. The synthesized hybrid adsorbent consisted of agarose beads modified with iminodiacetic (IDA) groups, loaded with immobilized Cu(II) ions, and PEG. These CAPPA media with grafted PEG on the interior and exterior surfaces of the agarose matrix were effective in rejecting high molecular weight proteins. Different PEG grafting densities and PEG of different molecular weight were tested to determine their effect in rejecting and controlling adsorbent permeation properties. Low grafting density of high molecular weight PEG was found to be as effective as high grafting density of low molecular weight PEG in the rejecting properties of the semi-permeable synthesized media.

Pancreatic serine protease extraction by affinity partition using a free triazine dye

Affinity partitioning combines the partitioning behavior of biological macromolecules in aqueous two-phase systems with the principle of biorecognition. Among the numerous substances that have been evaluated as ligands, the reactive dyes constitute a group of low cost textile dyes which have proved to act as biomimetic ligands for many enzymes. The ability of reactive yellow 2 (RY2) to interact with trypsin (TRP) and chymotrypsin (ChTRP) and its behavior in aqueous two-phase systems formed by polyethylene glycol (PEG) and sodium citrate (NaCit) – were investigated. Different variables such as PEG molecular weight, tie line length and dye concentration were analyzed. RY2 showed to bind specifically to both TRP and ChTRP with affinity constants near to 103M−1. Its partition equilibrium is practically displaced to the top phase in systems formed by PEG of different molecular weight. Addition of this dye to PEG 8000/NaCit systems until a final concentration of 0.196% (w/w) induced an increase in TRP and ChTRP partition coefficients of at least 2 times over that in the absence of the ligand. These findings demonstrate that RY2 fulfils all the requirements to be considered as an affinity ligand in aqueous two-phase partitioning of TRP and ChTRP.

Purification of lipase produced by a new source of Bacillus in submerged fermentation using an aqueous two-phase system

This work discusses the application of an aqueous two-phase system for the purification of lipases produced by Bacillus sp. ITP-001 using polyethylene glycol (PEG) and potassium phosphate. In the first step, the protein content was precipitated with ammonium sulphate (80% saturation). The enzyme remained in the aqueous solution and was dialyzed against ultra-pure water for 18 h and used to prepare an aqueous two-phase system (PEG/potassium phosphate). The use of different molecular weights of PEG to purify the lipase was investigated; the best purification factor (PF) was obtained using PEG 20,000 g/mol, however PEG 8000 was used in the next tests due to lower viscosity. The influence of PEG and potassium phosphate concentrations on the enzyme purification was then studied: the highest FP was obtained with 20% of PEG and 18% of potassium phosphate. NaCl was added to increase the hydrophobicity between the phases, and also increased the purification factor. The pH value and temperature affected the enzyme partitioning, with the best purifying conditions achieved at pH 6.0 and 4 °C. The molecular mass of the purified enzyme was determined to be approximately 54 kDa by SDS–PAGE. According to the results the best combination for purifying the enzyme is PEG 8000 g/mol and potassium phosphate (20/18%) with 6% of NaCl at pH 6.0 and 4 °C (201.53 fold). The partitioning process of lipase is governed by the entropy contribution.

Functionalized biopolymer based bipolar membrane with poly ethylene glycol interfacial layer for improved water splitting

This study investigates the effect of poly ethylene glycol (PEG) of different molecular weight (MW) as interfacial layer (IL) of bipolar membrane (BPM) for water dissociation. Chitosan (CS) was modified to N-methylene phosphonic chitosan (PC) and quaternized chitosan (QC), for preparing cation- and anion-exchange layer (CEL and AEL, respectively) of BPM. Different BPMs were prepared by layer-by-layer solution casting method (in aqueous media to achieve the good adhesion between layers) using PEG of different MWs (200–3400 Da) as IL. CEL and AEL with good ion-exchange properties were separately evaluated for their physicochemical and electrochemical characterizations. All BPMs with IL (PEG) were evaluated from current–voltage ( I– V) curves and water dissociation efficiency. The experimental results proved the excellent catalytic activity of PEG for water dissociation, which further improved with its MW. Furthermore, electrodialysis with bipolar membrane (EDBPM) experiments confirmed the occurrence of water dissociation at BPM interface and thus formation of acid and base.

Effect of the molecular weight of a polyethylene glycol on the photoluminescence spectra of porous TiO 2 films for dye-sensitized solar cells

Dye-sensitized solar cells (DSCs) are expected to be used for future clean energy. In general, when the titania porous electrode in DSCs is made, a polyethylene glycol (PEG) is added to obtain the porous structure. Although the conversion efficiency of the DSC became high when the high molecular weight of PEG was used, its reason was not clear. In the present study, the photoluminescence spectrum of titania films with the different molecular weight of PEG was measured at room temperature, and we discussed the relation between molecular weight and the conversion efficiency of the DSC.

Effect of Molecular Weight and Concentration of Polyethylene Glycol on Physicochemical Properties and Stability of Shellac Film

The effects of molecular weight and concentration of plasticizer on physicochemical properties and stability of shellac films were investigated. Type of plasticizer was previously reported to have some effects on the stability of shellac films, and polyethylene glycol (PEG) was the plasticizer of choice for plasticizing shellac films. In this study, different molecular weights of PEG (200, 400 and 4000) were chosen at a concentration of 10% w/w of shellac films. Shellac in alcohol was prepared in a free film. The stability of shellac film was then performed at 75% RH, 40 °C for 3 months. The comparison was made between the film with and without plasticizer. Shellac films were then determined for acid value, insoluble solid, mechanical properties and water vapor permeability coefficient. It was reported that different molecular weights of PEG had some influence on physicochemical properties of the shellac films. Among different molecular weights of PEG, PEG 400 showed a suitable molecular weight that could protect the shellac chain at the carboxylic and hydroxyl groups. Therefore, the molecular weight of plasticizer played a crucial role for the protective ability at active sites. Further study was performed to investigate the effect of concentrations of PEG 400 on the stability. The results demonstrated that PEG 400 at a concentration of 10% (w/w) could prevent the polymerization process for only 4 months and a significant change of all parameters was then reported. However, a higher concentration, 20% (w/w) of PEG 400, could prolong the stability of shellac for 6 months of study. Therefore, the drawback of shellac as a natural polymer in pharmaceutical and food industries could be tackled by the appropriate size and concentration of plasticizer.