The Experts below are selected from a list of 312 Experts worldwide ranked by ideXlab platform
Heather Sheardown - One of the best experts on this subject based on the ideXlab platform.
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poly ethylene glycol or silicone modified hyaluronan for contact lens Wetting Agent applications
Journal of Biomedical Materials Research Part A, 2015Co-Authors: Stefan M Paterson, Michael A Brook, Heather SheardownAbstract:Hyaluronan (HA) is a hydrophilic biopolymer that has been explored as a Wetting Agent in contact lens applications. In this study, HA was modified with siloxy or polyethylene glycol moieties using click chemistry to make it more soluble in monomer solutions used to synthesize model contact lens materials; unmodified HA was not soluble in the same monomer solutions. The water contents of the silicone hydrogels were not increased by the presence of modified HA, nor was there a decrease in the surface contact angle. However, modified HA did lead to a reduction in lysozyme adsorption in some cases. The leaching rate of HA modified with polyethylene glycol from a 78:22 DMA:TRIS(OH) hydrogel was significantly slower than for unmodified HA. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 2602–2610, 2015.
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Timolol maleate release from hyaluronic acid-containing model silicone hydrogel contact lens materials.
Journal of Biomaterials Applications, 2015Co-Authors: Myrto Korogiannaki, Lyndon Jones, Giuliano Guidi, Heather SheardownAbstract:This study was designed to assess the impact of a releasable Wetting Agent, such as hyaluronic acid (HA), on the release profile of timolol maleate (TM) from model silicone hydrogel contact lens materials. Polyvinylpyrrolidone (PVP) was used as an alternative Wetting Agent for comparison. The model lenses consisted of a hydrophilic monomer, either 2-hydroxyethyl methacrylate or N,N-dimethylacrylamide and a hydrophobic silicone monomer of methacryloxypropyltris (trimethylsiloxy) silane. The loading of the Wetting and the therapeutic Agent occurred during the synthesis of the silicone hydrogels through the method of direct entrapment. The developed materials were characterized by minimal changes in the water uptake, while lower molecular weight of HA improved their surface wettability. The transparency of the examined silicone hydrogels was found to be affected by the miscibility of the Wetting Agent in the prepolymer mixture as well as the composition of the developed silicone hydrogels. Sustained release ...
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hyaluronic acid as an internal Wetting Agent in model dmaa tris contact lenses
Journal of Biomaterials Applications, 2012Co-Authors: Andrea Weeks, Doerte Luensmann, Adrienne Boone, Lyndon Jones, Heather SheardownAbstract:Model silicone hydrogel contact lenses, comprised of N,N-dimethylacrylamide and methacryloxypropyltris (trimethylsiloxy) silane, were fabricated and hyaluronic acid (HA) was incorporated as an internal Wetting Agent using a dendrimer-based method. HA and dendrimers were loaded into the silicone hydrogels and cross-linked using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide chemistry. The presence and location of HA in the hydrogels was confirmed using X-ray photoelectron spectroscopy and confocal laser scanning microscopy, respectively. The effects of the presence of HA on the silicone hydrogels on hydrophilicity, swelling behavior, transparency, and lysozyme sorption and denaturation were evaluated. The results showed that HA increased the hydrophilicity and the equilibrium water content of the hydrogels without affecting transparency. HA also significantly decreased the amount of lysozyme sorption (p < 0.002). HA had no effect on lysozyme denaturation in hydrogels containing 0% and 1.7% methacrylic acid...
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photocrosslinkable hyaluronic acid as an internal Wetting Agent in model conventional and silicone hydrogel contact lenses
Journal of Biomedical Materials Research Part A, 2012Co-Authors: Andrea Weeks, Lyndon Jones, Michael A Brook, David Morrison, Johan G Alauzun, Heather SheardownAbstract:Photocrosslinkable methacrylated hyaluronic acid (HA) was prepared and incorporated into model conventional and silicone hydrogel contact lenses as an internal Wetting Agent. The molecular weight of the HA, the degree of methacrylation as well as the amount (0.25 to 1.0 wt %) incorporated were varied. The HA-containing hydrogels were analyzed using a variety of techniques including water contact angles, equilibrium water content (EWC), and lysozyme sorption. The presence of HA could be detected in the materials using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy—attenuated total reflectance. The materials containing methacrylated HA had improved hydrophilicity and reduced lysozyme sorption. Effects of modified HA on EWC were dependent upon the materials but generally increased water uptake. Increased mobility of the HA associated with a lower molecular weight and lower degree of methacrylation was found to be more effective in improving hydrophilicity and decreasing lysozyme sorption than the less mobile HA. All results found suggest that photocrosslinkable HA has significant potential in contact lens applications. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
Lyndon Jones - One of the best experts on this subject based on the ideXlab platform.
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Timolol maleate release from hyaluronic acid-containing model silicone hydrogel contact lens materials.
Journal of Biomaterials Applications, 2015Co-Authors: Myrto Korogiannaki, Lyndon Jones, Giuliano Guidi, Heather SheardownAbstract:This study was designed to assess the impact of a releasable Wetting Agent, such as hyaluronic acid (HA), on the release profile of timolol maleate (TM) from model silicone hydrogel contact lens materials. Polyvinylpyrrolidone (PVP) was used as an alternative Wetting Agent for comparison. The model lenses consisted of a hydrophilic monomer, either 2-hydroxyethyl methacrylate or N,N-dimethylacrylamide and a hydrophobic silicone monomer of methacryloxypropyltris (trimethylsiloxy) silane. The loading of the Wetting and the therapeutic Agent occurred during the synthesis of the silicone hydrogels through the method of direct entrapment. The developed materials were characterized by minimal changes in the water uptake, while lower molecular weight of HA improved their surface wettability. The transparency of the examined silicone hydrogels was found to be affected by the miscibility of the Wetting Agent in the prepolymer mixture as well as the composition of the developed silicone hydrogels. Sustained release ...
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hyaluronic acid as an internal Wetting Agent in model dmaa tris contact lenses
Journal of Biomaterials Applications, 2012Co-Authors: Andrea Weeks, Doerte Luensmann, Adrienne Boone, Lyndon Jones, Heather SheardownAbstract:Model silicone hydrogel contact lenses, comprised of N,N-dimethylacrylamide and methacryloxypropyltris (trimethylsiloxy) silane, were fabricated and hyaluronic acid (HA) was incorporated as an internal Wetting Agent using a dendrimer-based method. HA and dendrimers were loaded into the silicone hydrogels and cross-linked using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide chemistry. The presence and location of HA in the hydrogels was confirmed using X-ray photoelectron spectroscopy and confocal laser scanning microscopy, respectively. The effects of the presence of HA on the silicone hydrogels on hydrophilicity, swelling behavior, transparency, and lysozyme sorption and denaturation were evaluated. The results showed that HA increased the hydrophilicity and the equilibrium water content of the hydrogels without affecting transparency. HA also significantly decreased the amount of lysozyme sorption (p < 0.002). HA had no effect on lysozyme denaturation in hydrogels containing 0% and 1.7% methacrylic acid...
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photocrosslinkable hyaluronic acid as an internal Wetting Agent in model conventional and silicone hydrogel contact lenses
Journal of Biomedical Materials Research Part A, 2012Co-Authors: Andrea Weeks, Lyndon Jones, Michael A Brook, David Morrison, Johan G Alauzun, Heather SheardownAbstract:Photocrosslinkable methacrylated hyaluronic acid (HA) was prepared and incorporated into model conventional and silicone hydrogel contact lenses as an internal Wetting Agent. The molecular weight of the HA, the degree of methacrylation as well as the amount (0.25 to 1.0 wt %) incorporated were varied. The HA-containing hydrogels were analyzed using a variety of techniques including water contact angles, equilibrium water content (EWC), and lysozyme sorption. The presence of HA could be detected in the materials using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy—attenuated total reflectance. The materials containing methacrylated HA had improved hydrophilicity and reduced lysozyme sorption. Effects of modified HA on EWC were dependent upon the materials but generally increased water uptake. Increased mobility of the HA associated with a lower molecular weight and lower degree of methacrylation was found to be more effective in improving hydrophilicity and decreasing lysozyme sorption than the less mobile HA. All results found suggest that photocrosslinkable HA has significant potential in contact lens applications. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
Michael A Brook - One of the best experts on this subject based on the ideXlab platform.
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poly ethylene glycol or silicone modified hyaluronan for contact lens Wetting Agent applications
Journal of Biomedical Materials Research Part A, 2015Co-Authors: Stefan M Paterson, Michael A Brook, Heather SheardownAbstract:Hyaluronan (HA) is a hydrophilic biopolymer that has been explored as a Wetting Agent in contact lens applications. In this study, HA was modified with siloxy or polyethylene glycol moieties using click chemistry to make it more soluble in monomer solutions used to synthesize model contact lens materials; unmodified HA was not soluble in the same monomer solutions. The water contents of the silicone hydrogels were not increased by the presence of modified HA, nor was there a decrease in the surface contact angle. However, modified HA did lead to a reduction in lysozyme adsorption in some cases. The leaching rate of HA modified with polyethylene glycol from a 78:22 DMA:TRIS(OH) hydrogel was significantly slower than for unmodified HA. © 2014 Wiley Periodicals, Inc. J Biomed Mater Res Part A: 103A: 2602–2610, 2015.
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photocrosslinkable hyaluronic acid as an internal Wetting Agent in model conventional and silicone hydrogel contact lenses
Journal of Biomedical Materials Research Part A, 2012Co-Authors: Andrea Weeks, Lyndon Jones, Michael A Brook, David Morrison, Johan G Alauzun, Heather SheardownAbstract:Photocrosslinkable methacrylated hyaluronic acid (HA) was prepared and incorporated into model conventional and silicone hydrogel contact lenses as an internal Wetting Agent. The molecular weight of the HA, the degree of methacrylation as well as the amount (0.25 to 1.0 wt %) incorporated were varied. The HA-containing hydrogels were analyzed using a variety of techniques including water contact angles, equilibrium water content (EWC), and lysozyme sorption. The presence of HA could be detected in the materials using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy—attenuated total reflectance. The materials containing methacrylated HA had improved hydrophilicity and reduced lysozyme sorption. Effects of modified HA on EWC were dependent upon the materials but generally increased water uptake. Increased mobility of the HA associated with a lower molecular weight and lower degree of methacrylation was found to be more effective in improving hydrophilicity and decreasing lysozyme sorption than the less mobile HA. All results found suggest that photocrosslinkable HA has significant potential in contact lens applications. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
Andrea Weeks - One of the best experts on this subject based on the ideXlab platform.
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hyaluronic acid as an internal Wetting Agent in model dmaa tris contact lenses
Journal of Biomaterials Applications, 2012Co-Authors: Andrea Weeks, Doerte Luensmann, Adrienne Boone, Lyndon Jones, Heather SheardownAbstract:Model silicone hydrogel contact lenses, comprised of N,N-dimethylacrylamide and methacryloxypropyltris (trimethylsiloxy) silane, were fabricated and hyaluronic acid (HA) was incorporated as an internal Wetting Agent using a dendrimer-based method. HA and dendrimers were loaded into the silicone hydrogels and cross-linked using 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide chemistry. The presence and location of HA in the hydrogels was confirmed using X-ray photoelectron spectroscopy and confocal laser scanning microscopy, respectively. The effects of the presence of HA on the silicone hydrogels on hydrophilicity, swelling behavior, transparency, and lysozyme sorption and denaturation were evaluated. The results showed that HA increased the hydrophilicity and the equilibrium water content of the hydrogels without affecting transparency. HA also significantly decreased the amount of lysozyme sorption (p < 0.002). HA had no effect on lysozyme denaturation in hydrogels containing 0% and 1.7% methacrylic acid...
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photocrosslinkable hyaluronic acid as an internal Wetting Agent in model conventional and silicone hydrogel contact lenses
Journal of Biomedical Materials Research Part A, 2012Co-Authors: Andrea Weeks, Lyndon Jones, Michael A Brook, David Morrison, Johan G Alauzun, Heather SheardownAbstract:Photocrosslinkable methacrylated hyaluronic acid (HA) was prepared and incorporated into model conventional and silicone hydrogel contact lenses as an internal Wetting Agent. The molecular weight of the HA, the degree of methacrylation as well as the amount (0.25 to 1.0 wt %) incorporated were varied. The HA-containing hydrogels were analyzed using a variety of techniques including water contact angles, equilibrium water content (EWC), and lysozyme sorption. The presence of HA could be detected in the materials using X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy—attenuated total reflectance. The materials containing methacrylated HA had improved hydrophilicity and reduced lysozyme sorption. Effects of modified HA on EWC were dependent upon the materials but generally increased water uptake. Increased mobility of the HA associated with a lower molecular weight and lower degree of methacrylation was found to be more effective in improving hydrophilicity and decreasing lysozyme sorption than the less mobile HA. All results found suggest that photocrosslinkable HA has significant potential in contact lens applications. © 2012 Wiley Periodicals, Inc. J Biomed Mater Res Part A, 2012.
Majid S. Hashmi - One of the best experts on this subject based on the ideXlab platform.
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The enhancement of wettability of SiC particles in cast aluminium matrix composites
Journal of Materials Processing Technology, 2001Co-Authors: J. Hashim, Lisa Looney, Majid S. HashmiAbstract:Many methods have been proposed to overcome the problem of poor wettability between ceramic reinforcement particles and molten aluminium for metal matrix composite (MMC) production by casting. Some of these methods are expensive and complex, and a cheap and simple technique still to be found. In this paper, an innovative approach to fabricating cast MMCs is proposed. In order to study the enhancement of wettability of SiC particles by the matrix alloy A359, a casting rig was specially designed, and tests carried out using the A359 matrix alloy, SiC particles, and magnesium (as a Wetting Agent). Stirring of these mixtures was performed under several different conditions, and the effect of this stirring action on the wettability enhancement was studied. The percentage of particles entrapped in the resulting composite was used as a measure of wettability, and plotted against cooling time and volume percentage of SiC particles. The use of clean SiC particles, magnesium as a Wetting Agent, and stirring continuously while the MMC slurry is solidifying were found to promote wettability of SiC with A359 matrix alloy. Decreasing this solidification time was also found to improve the wettability, whereas increasing the volume fraction of SiC particles present will give the opposite effect. © 2001 Elsevier Science B.V. All rights reserved.
