The Experts below are selected from a list of 111 Experts worldwide ranked by ideXlab platform
Si-shen Feng - One of the best experts on this subject based on the ideXlab platform.
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Preparation and characterization of poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA) microspheres for controlled release of paclitaxel.
Biomaterials, 2003Co-Authors: Gang Ruan, Si-shen FengAbstract:Microspheres of a new kind of copolymer, poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA), are proposed in the present work for clinical administration of an antineoplastic drug paclitaxel with hypothesis that incorporation of a hydrophilic PEG segment within the hydrophobic PLA might facilitate the paclitaxel release. Paclitaxel-loaded PLA-PEG-PLA microspheres of various compositions were prepared by the Solvent extraction/evaporation method. Characterization of the microspheres was then followed to examine the particle size and size distribution, the drug encapsulation efficiency, the colloidal stability, the surface chemistry, the surface and internal morphology, the drug physical state and its in vitro release behavior. The effects of polymer types, Solvents and drug loading were investigated. It was found that in the microspheres the PEG segment was homogeneously distributed and caused porosity. Significantly faster release from PLA-PEG-PLA microspheres resulted in comparison with the PLGA counterpart. Incorporation of Water-Soluble Solvent acetone in the organic Solvent phase further increased the porosity of the PLA-PEG-PLA microspheres and facilitated the drug release. A total of 49.6% sustained release of paclitaxel within 1 month was achieved. Potentially, the presence of PEG on the surface of PLA-PEG-PLA microspheres could improve their biocompatibility. PLA-PEG-PLA microspheres could thus be promising for the clinical administration of highly hydrophobic antineoplastic drugs such as paclitaxel.
Gang Ruan - One of the best experts on this subject based on the ideXlab platform.
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Preparation and characterization of poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA) microspheres for controlled release of paclitaxel.
Biomaterials, 2003Co-Authors: Gang Ruan, Si-shen FengAbstract:Microspheres of a new kind of copolymer, poly(lactic acid)-poly(ethylene glycol)-poly(lactic acid) (PLA-PEG-PLA), are proposed in the present work for clinical administration of an antineoplastic drug paclitaxel with hypothesis that incorporation of a hydrophilic PEG segment within the hydrophobic PLA might facilitate the paclitaxel release. Paclitaxel-loaded PLA-PEG-PLA microspheres of various compositions were prepared by the Solvent extraction/evaporation method. Characterization of the microspheres was then followed to examine the particle size and size distribution, the drug encapsulation efficiency, the colloidal stability, the surface chemistry, the surface and internal morphology, the drug physical state and its in vitro release behavior. The effects of polymer types, Solvents and drug loading were investigated. It was found that in the microspheres the PEG segment was homogeneously distributed and caused porosity. Significantly faster release from PLA-PEG-PLA microspheres resulted in comparison with the PLGA counterpart. Incorporation of Water-Soluble Solvent acetone in the organic Solvent phase further increased the porosity of the PLA-PEG-PLA microspheres and facilitated the drug release. A total of 49.6% sustained release of paclitaxel within 1 month was achieved. Potentially, the presence of PEG on the surface of PLA-PEG-PLA microspheres could improve their biocompatibility. PLA-PEG-PLA microspheres could thus be promising for the clinical administration of highly hydrophobic antineoplastic drugs such as paclitaxel.
Thomas E. Rufford - One of the best experts on this subject based on the ideXlab platform.
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A phase inversion polymer coating to prevent swelling and spalling of clay fines in coal seam gas wells
International Journal of Coal Science & Technology, 2018Co-Authors: Christopher Hamilton, Victor Rudolph, Rahmah Tasha Febrina, Thomas E. RuffordAbstract:We report a phase inversion polymer coating as a novel concept with potential to prevent clay swelling and fines generation in coal seam gas, or other petroleum, wellbores. Our approach uses polyethersulfone (PES) with N -methyl-2-pyrrolidone (NMP) as a Water-Soluble Solvent to form a dense, low-porosity film across the clay-rich interburden layers, but a porous and permeable membrane on coal seams. This contrasting behaviour occurs because the coal contains much more free Water than the clay-rich interburden layers. We demonstrate the efficacy of the method to prevent clay spalling in immersion tests and under a flow of fresh Water in a visual swell test apparatus. The clay-rich rocks studied were mudstone and siltstone, and these were dip coated in the PES/NMP solution. The uncoated mudstone swelled and broke apart quickly in the immersion test and visual flow test, but the PES coated rock samples were stable for 30 days. The coated rock and coal samples were characterised by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The morphology of coated mudstone and coated coal samples showed that the polymer formed a dense layer across the low-permeability mudstone, but an open porous structure on the coal surface. The effect of the coating on the permeability of KCl brine through coal was measured in a core-flood apparatus. Although the permeability of the coal showed some deterioration after coating, from (0.58 ± 0.12) mD to (0.3 ± 0.03) mD, these results demonstrate the potential of a smart polymer coating to prevent clay swelling while remaining permeable to gas and Water on coal layers.
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Smart, Porous Polymer Coatings to Bind Clay Minerals in Coal Bed Methane Wells
Day 3 Wed November 16 2016, 2016Co-Authors: Christopher Hamilton, Tasha Rahman Ferbina, Victor Rudolph, Thomas E. RuffordAbstract:We report a phase inversion polymer coating to prevent clay swelling and fines production in coal seam gas (coal bed methane) or other petroleum well bores. Importantly, this coating remains permeable to gas and Water flow across producing coal seams. This approach uses a Water-Soluble Solvent that can form a low-porosity, dense membrane across clay-containing interburden layers, which contain less free Water than the coal matrix, but form a porous membrane across the coal layer. Problematic interburden samples and reference coal samples were from a core sample obtained from a coal seam gas well in the Surat Basin, Queensland. The mixture of polymer coating solution (polyethersulfone (PES)/N-methyl-2-pyrrolidinone (NMP)) was prepared and cast onto the target samples by a simple dip method, followed by the phase-inversion step. Polymer coatings were characterised by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The SEM images of coated mudstone and coated coal samples showed that the polymer formed a dense layer across the low-permeability mudstone, but an open porous structure was formed on the coal surface. The uncoated rock samples and polymer coated samples were exposed to a flow of distilled Water, and the formation of any fine particles was observed by video camera. The flow tests show that the PES coating can significantly improve the stability of interburden samples containing swellable clays.
Roberto Fernandez-lafuente - One of the best experts on this subject based on the ideXlab platform.
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Enzyme-Coated Micro-Crystals: An Almost Forgotten but Very Simple and Elegant Immobilization Strategy
Catalysts, 2020Co-Authors: Rodolpho R. C. Monteiro, José C. S. Dos Santos, Andrés R. Alcántara, Roberto Fernandez-lafuenteAbstract:The immobilization of enzymes using protein coated micro-crystals (PCMCs) was reported for the first time in 2001 by Kreiner and coworkers. The strategy is very simple. First, an enzyme solution must be prepared in a concentrated solution of one compound (salt, sugar, amino acid) very Soluble in Water and poorly Soluble in a Water-Soluble Solvent. Then, the enzyme solution is added dropwise to the Water Soluble Solvent under rapid stirring. The components accompanying the enzyme are called the crystal growing agents, the Solvent being the dehydrating agent. This strategy permits the rapid dehydration of the enzyme solution drops, resulting in a crystallization of the crystal formation agent, and the enzyme is deposited on this crystal surface. The reaction medium where these biocatalysts can be used is marked by the solubility of the PCMC components, and usually these biocatalysts may be employed in Water Soluble organic Solvents with a maximum of 20% Water. The evolution of these PCMC was to chemically crosslink them and further improve their stabilities. Moreover, the PCMC strategy has been used to coimmobilize enzymes or enzymes and cofactors. The immobilization may permit the use of buffers as crystal growth agents, enabling control of the reaction pH in the enzyme environments. Usually, the PCMC biocatalysts are very stable and more active than other biocatalysts of the same enzyme. However, this simple (at least at laboratory scale) immobilization strategy is underutilized even when the publications using it systematically presented a better performance of them in organic Solvents than that of many other immobilized biocatalysts. In fact, many possibilities and studies using this technique are lacking. This review tried to outline the possibilities of this useful immobilization strategy.
Christopher Hamilton - One of the best experts on this subject based on the ideXlab platform.
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A phase inversion polymer coating to prevent swelling and spalling of clay fines in coal seam gas wells
International Journal of Coal Science & Technology, 2018Co-Authors: Christopher Hamilton, Victor Rudolph, Rahmah Tasha Febrina, Thomas E. RuffordAbstract:We report a phase inversion polymer coating as a novel concept with potential to prevent clay swelling and fines generation in coal seam gas, or other petroleum, wellbores. Our approach uses polyethersulfone (PES) with N -methyl-2-pyrrolidone (NMP) as a Water-Soluble Solvent to form a dense, low-porosity film across the clay-rich interburden layers, but a porous and permeable membrane on coal seams. This contrasting behaviour occurs because the coal contains much more free Water than the clay-rich interburden layers. We demonstrate the efficacy of the method to prevent clay spalling in immersion tests and under a flow of fresh Water in a visual swell test apparatus. The clay-rich rocks studied were mudstone and siltstone, and these were dip coated in the PES/NMP solution. The uncoated mudstone swelled and broke apart quickly in the immersion test and visual flow test, but the PES coated rock samples were stable for 30 days. The coated rock and coal samples were characterised by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The morphology of coated mudstone and coated coal samples showed that the polymer formed a dense layer across the low-permeability mudstone, but an open porous structure on the coal surface. The effect of the coating on the permeability of KCl brine through coal was measured in a core-flood apparatus. Although the permeability of the coal showed some deterioration after coating, from (0.58 ± 0.12) mD to (0.3 ± 0.03) mD, these results demonstrate the potential of a smart polymer coating to prevent clay swelling while remaining permeable to gas and Water on coal layers.
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Smart, Porous Polymer Coatings to Bind Clay Minerals in Coal Bed Methane Wells
Day 3 Wed November 16 2016, 2016Co-Authors: Christopher Hamilton, Tasha Rahman Ferbina, Victor Rudolph, Thomas E. RuffordAbstract:We report a phase inversion polymer coating to prevent clay swelling and fines production in coal seam gas (coal bed methane) or other petroleum well bores. Importantly, this coating remains permeable to gas and Water flow across producing coal seams. This approach uses a Water-Soluble Solvent that can form a low-porosity, dense membrane across clay-containing interburden layers, which contain less free Water than the coal matrix, but form a porous membrane across the coal layer. Problematic interburden samples and reference coal samples were from a core sample obtained from a coal seam gas well in the Surat Basin, Queensland. The mixture of polymer coating solution (polyethersulfone (PES)/N-methyl-2-pyrrolidinone (NMP)) was prepared and cast onto the target samples by a simple dip method, followed by the phase-inversion step. Polymer coatings were characterised by X-ray diffraction, Fourier transform infrared spectroscopy and scanning electron microscopy. The SEM images of coated mudstone and coated coal samples showed that the polymer formed a dense layer across the low-permeability mudstone, but an open porous structure was formed on the coal surface. The uncoated rock samples and polymer coated samples were exposed to a flow of distilled Water, and the formation of any fine particles was observed by video camera. The flow tests show that the PES coating can significantly improve the stability of interburden samples containing swellable clays.
