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PEG Concentration (peg + concentration)
Selected AbstractsControl of thermo reversible gelation of methylcellulose using polyethylene glycol and sodium chloride for sustained delivery of ophthalmic drugJOURNAL OF APPLIED POLYMER SCIENCE, Issue 2 2010Mrinal Kanti Bain Abstract The effect of molecular weight of polyethyleneglycol (PEG) and sodium chloride (NaCl) on the gelation temperature of methylcellulose (MC) was studied with the objective to develop a MC based formulation for sustained delivery of ophthalmic drug. The gelation temperature of 1% MC was 60 ± 0.40°C. It was found that the gelation temperature of MC was reduced with the addition of 10% PEG and extent of reduction of gelation temperature was depended on the molecular weight of PEG at same PEG concentration of 10%. The gelation temperature of MC was reduced by 10.4 to 5.9°C with the increasing molecular weight of PEG starting from 400 to 20,000 (Mn) depending on the method of determination of gelation temperature. To reduce the gelation temperature of MC close to physiological temperature (37°C), 6% NaCl was added in the different MC-PEG combinations containing different molecular weight of PEG. It was observed that the drug release time increased from 5 to 8 h with the increase in molecular weight of PEG from 400 to 20,000 (Mn) and this was due to the maximum viscosity and gel strength of MC-PEG20000-NaCl ternary combination. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2010 [source] Effects of vanillin and plasticizer on properties of chitosan-methyl cellulose based filmJOURNAL OF APPLIED POLYMER SCIENCE, Issue 6 2008Jurmkwan Sangsuwan Abstract Chitosan-methyl cellulose based films which incorporatate vanillin as an antimicrobial agent and polyethylene glycol 400 (PEG) as a plasticizer were developed in this study. The effects of vanillin and plasticizer concentration on mechanical, barrier, optical, and thermal properties of chitosan-methyl cellulose film were evaluated. When the vanillin concentration was increased at a given PEG level, film flexibility decreased while tensile strength increased slightly. Vanillin increased the barrier to oxygen but not water vapor. Increasing vanillin content resulted in less transparency and a more yellowish tint. The bulky nature of vanillin reduced film crystallization. When PEG concentration was increased at a given vanillin level, it resulted in greater film flexibility but reduced film strength. Water vapor permeability (WVP) and oxygen permeability (OP) increased with increase in PEG content. PEG contributed less to the opacity, yellowness, and crystallization of the film than did vanillin. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008 [source] Dissolution of artemisinin/polymer composite nanoparticles fabricated by evaporative precipitation of nanosuspensionJOURNAL OF PHARMACY AND PHARMACOLOGY: AN INTERNATI ONAL JOURNAL OF PHARMACEUTICAL SCIENCE, Issue 4 2010Mitali Kakran Abstract Objectives An evaporative precipitation of nanosuspension (EPN) method was used to fabricate composite particles of a poorly water-soluble antimalarial drug, artemisinin, with a hydrophilic polymer, polyethylene glycol (PEG), with the aim of enhancing the dissolution rate of artemisinin. We investigated the effect of polymer concentration on the physical, morphological and dissolution properties of the EPN-prepared artemisinin/PEG composites. Methods The original artemisinin powder, EPN-prepared artemisinin nanoparticles and artemisinin/PEG composites were characterised by scanning electron microscopy, Fourier-transform infrared spectroscopy, differential scanning calorimetry (DSC), X-ray diffraction (XRD), dissolution testing and HPLC. The percentage dissolution efficiency, relative dissolution, time to 75% dissolution and mean dissolution time were calculated. The experimental drug dissolution data were fitted to various mathematical models (Weibull, first-order, Korsemeyer,Peppas, Hixson,Crowell cube root and Higuchi models) in order to analyse the release mechanism. Key findings The DSC and XRD studies suggest that the crystallinity of the EPN-prepared artemisinin decreased with increasing polymer concentration. The phase-solubility studies revealed an AL -type curve, indicating a linear increase in drug solubility with PEG concentration. The dissolution rate of the EPN-prepared artemisinin and artemisinin/PEG composites increased markedly compared with the original artemisinin powder. Conclusions EPN can be used to prepare artemisinin nanoparticles and artemisinin/PEG composite particles that have a significantly enhanced dissolution rate. The mechanism of drug release involved diffusion and erosion. [source] Design of Blends with an Extremely Low Viscosity Ratio between the Dispersed and Continuous Phases.MACROMOLECULAR SYMPOSIA, Issue 1 2007Dependence of the Dispersed Phase Size on the Processing Parameters Abstract Summary: This work deals with the development of the dispersed phase morphology in immiscible blends of poly(ethylene glycol)/polyamide 66 (PEG/PA) with an extremely low viscosity ratio. The blends were obtained, under different operating conditions, by melt blending in an internal mixer. The objective was to examine the influence of the main processing parameters on the particles size of the minor phase (PEG). A model was elaborated to describe the dependence of the particle size on interfacial tension, PEG concentration, shear rate and viscosity ratio between the two blend components. [source] Hydrogels assembled by inclusion complexation of poly(ethylene glycol) with alpha-cyclodextrinASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 5 2009Jie Wang Abstract Polymeric hydrogels were prepared based on the inclusive complexation between ,-cyclodextrin (,-CD) and poly(ethylene glycol) (PEG). Because the rheological property of a thermodynamic stable hydrogel should be gap-independent, it is found in this work that the uniformed hydrogel can be distinguished from gel-like aggregation by changing the plate gap during the rheological measurement. By this rheological method it is determined that suitable storage duration is necessary for the preparation of uniform hydrogels. However, the sonication technique after mixing CD and PEG solutions or increasing PEG concentration can shorten the time to form stable hydrogels. Moreover, the molecular weight of PEG should be high enough (,8000 g/mol) for sol-gel transition. The higher the molecular weight of PEG is, the longer storage time is needed to obtain a uniform hydrogel. From the observation by differential scanning calorimetry (DSC) and X-ray diffraction (XRD) of prepared hydrogels, we concluded that the driving force of networks should be attributed to the crystallization of complexed ,-CDs in the ,-CD/PEG pseudo-polyrotaxanes. Copyright © 2009 Curtin University of Technology and John Wiley & Sons, Ltd. [source] Crystallization of recombinant human growth hormone at elevated pressures: Pressure effects on PEG-induced volume exclusion interactionsBIOTECHNOLOGY & BIOENGINEERING, Issue 4 2010Ryan L. Crisman Abstract Crystallization of recombinant human growth hormone (rhGH) at elevated pressures was investigated in the presence of 6,000 molecular weight poly(ethylene glycol; PEG-6000). Crystallization of rhGH at atmospheric pressure occurred at a protein concentration of 15,mg/mL in 6% PEG-6000. Crystallization did not occur in the same solutions at 250,MPa. In contrast, at a pressure of 250,MPa in the presence of 8% PEG-6000, rhGH readily crystallized from solutions containing 35,mg/mL rhGH, whereas amorphous precipitate formed in the same solutions at atmospheric pressure. Osmotic virial coefficients were determined from static light scattering measurements and combined with a hard-sphere activity coefficient model to predict rhGH activity coefficients as a function of pressure and PEG concentration. Predicted activity coefficients quantitatively matched those determined from equilibrium solubility measurements. The ability to adjust the thermodynamic non-ideality with pressure provides a valuable tool to study protein crystallization in addition to providing a methodology for obtaining crystals at elevated pressures. Biotechnol. Bioeng. 2010;107:663,672. © 2010 Wiley Periodicals, Inc. [source] Effect of polyethylene glycol on the thermal stability of green fluorescent proteinBIOTECHNOLOGY PROGRESS, Issue 1 2010Letícia C. de Lencastre Novaes Abstract Green fluorescent protein (GFP) shows remarkable structural stability and high fluorescence; its stability can be directly related to its fluorescence output, among other characteristics. GFP is stable under increasing temperatures, and its thermal denaturation is highly reproducible. Some polymers, such as polyethylene glycol, are often used as modifiers of characteristics of biological macromolecules, to improve the biochemical activity and stability of proteins or drug bioavailability. The aim of this study was to evaluate the thermal stability of GFP in the presence of different PEG molar weights at several concentrations and exposed to constant temperatures, in a range of 70,95°C. Thermal stability was expressed in decimal reduction time. It was observed that the D -values obtained were almost constant for temperatures of 85, 90, and 95°C, despite the PEG concentration or molar weight studied. Even though PEG can stabilize proteins, only at 75°C, PEG 600 and 4,000 g/mol stabilized GFP. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] High-throughput screening techniques for rapid PEG-based precipitation of IgG4 mAb from clarified cell culture supernatantBIOTECHNOLOGY PROGRESS, Issue 3 2010Carol Knevelman Abstract Locating optimal protein precipitation conditions for complex biological feed materials is problematic. This article describes the application of a series of high-throughput platforms for the rapid identification and selection of conditions for the precipitation of an IgG4 monoclonal antibody (mAb) from a complex feedstock using only microliter quantities of material. The approach uses 96-microwell filter plates combined with high-throughput analytical methods and a method for well volume determination for product quantification. The low material, time and resource requirements facilitated the use of a full factorial Design of Experiments (DoE) for the rapid investigation into how critical parameters impact the IgG4 precipitation. To aid the DoE, a set of preliminary range-finding studies were conducted first. Data collected through this approach describing Polyethylene Glycol (PEG) precipitation of the IgG4 as a function of mAb concentration, precipitant concentration, and pH are presented. Response surface diagrams were used to explore interactions between parameters and to inform selection of the most favorable conditions for maximum yield and purification. PEG concentrations required for maximum yield and purity were dependant on the IgG4 concentration; however, concentrations of 14 to 20% w/v, pH 6.5, gave optimal levels of yield and purity. Application of the high-throughput approach enabled 1,155 conditions to be examined with less than 1 g of material. The level of insights gained over such a short time frame is indicative of the power of microwell experimentation in allowing the rapid identification of appropriate processing conditions for key bioprocess operations. © 2009 American Institute of Chemical Engineers Biotechnol. Prog., 2010 [source] | |||||||||||||