The Experts below are selected from a list of 1908 Experts worldwide ranked by ideXlab platform
Jorge Carballido-landeira - One of the best experts on this subject based on the ideXlab platform.
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Temporal viscosity modulations driven by a pH sensitive polymer coupled to a pH-changing chemical reaction.
Physical chemistry chemical physics : PCCP, 2017Co-Authors: D. M. Escala, Alberto P. Muñuzuri, A. De Wit, Jorge Carballido-landeiraAbstract:The Formaldehyde-Sulfite (FS) and the Formaldehyde-Sulfite-Gluconolactone (FSG) systems are examples of complex chemical reactions accompanied by well-controlled variations in pH. While the FS system exhibits a clock behavior, in the FSG reaction, this mechanism is coupled with the hydrolysis of the Gluconolactone which gives the possibility to show large temporal oscillations of pH in an open reactor. In this work, we show how these reactive systems, due to their organic nature, can be coupled with pH sensitive polymers, particularly with polyacrylic acid (PAA) to trigger temporal changes of viscosity. We characterize this coupled reactive system showing the effects of changes in the initial concentrations of the polymer and in the chemical reagents on the induction time, the magnitude of the pH variations and the temporal modifications of the viscosity.
D. M. Escala - One of the best experts on this subject based on the ideXlab platform.
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Temporal viscosity modulations driven by a pH sensitive polymer coupled to a pH-changing chemical reaction.
Physical chemistry chemical physics : PCCP, 2017Co-Authors: D. M. Escala, Alberto P. Muñuzuri, A. De Wit, Jorge Carballido-landeiraAbstract:The Formaldehyde-Sulfite (FS) and the Formaldehyde-Sulfite-Gluconolactone (FSG) systems are examples of complex chemical reactions accompanied by well-controlled variations in pH. While the FS system exhibits a clock behavior, in the FSG reaction, this mechanism is coupled with the hydrolysis of the Gluconolactone which gives the possibility to show large temporal oscillations of pH in an open reactor. In this work, we show how these reactive systems, due to their organic nature, can be coupled with pH sensitive polymers, particularly with polyacrylic acid (PAA) to trigger temporal changes of viscosity. We characterize this coupled reactive system showing the effects of changes in the initial concentrations of the polymer and in the chemical reagents on the induction time, the magnitude of the pH variations and the temporal modifications of the viscosity.
Sergey M. Ksenzenko - One of the best experts on this subject based on the ideXlab platform.
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The Polyhydroxy Acid Gluconolactone Protects Against Ultraviolet Radiation in an In Vitro Model of Cutaneous Photoaging
Dermatologic Surgery, 2004Co-Authors: Eric F. Bernstein, Douglas B. Brown, Mark Schwartz, Kays Kaidbey, Sergey M. KsenzenkoAbstract:Background. Ultraviolet (UV) radiation damages skin through a variety of mechanisms, including the generation of free radicals. Gluconolactone is a polyhydroxy acid (PHA) that is capable of chelating metals and may also function by scavenging free radicals, thereby protecting skin from some of the damaging effects of UV radiation. Objective. This study measured the ability of Gluconolactone to protect against UV radiation–induced damage. Methods. The ability of Gluconolactone to prevent UV radiation–induced elastin promoter activation was determined in vitro using a transgenic model of cutaneous photoaging. Gluconolactone was also evaluated to determine its ability to promote the formation of sunburn cells in human skin after exposure to UV radiation. Results. Gluconolactone provided up to 50% protection against UV radiation, as measured in our in vitro system, and did not significantly increase sunburn cells in human skin. Conclusions. These results demonstrate the ability of the PHA Gluconolactone to protect against UV radiation–induced elastin promoter activation. In addition, in vivo studies demonstrated that Gluconolactone treatment does not result in a significant increase in sunburn cells. Further investigation of this and other PHAs is necessary to identify their potential role in preventing and repairing cutaneous photodamage.
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The polyhydroxy acid Gluconolactone protects against ultraviolet radiation in an in vitro model of cutaneous photoaging.
Dermatologic surgery : official publication for American Society for Dermatologic Surgery [et al.], 2004Co-Authors: Eric F. Bernstein, Douglas B. Brown, Kays Kaidbey, Mark D Schwartz, Sergey M. KsenzenkoAbstract:Ultraviolet (UV) radiation damages skin through a variety of mechanisms, including the generation of free radicals. Gluconolactone is a polyhydroxy acid (PHA) that is capable of chelating metals and may also function by scavenging free radicals, thereby protecting skin from some of the damaging effects of UV radiation. This study measured the ability of Gluconolactone to protect against UV radiation-induced damage. The ability of Gluconolactone to prevent UV radiation-induced elastin promoter activation was determined in vitro using a transgenic model of cutaneous photoaging. Gluconolactone was also evaluated to determine its ability to promote the formation of sunburn cells in human skin after exposure to UV radiation. Gluconolactone provided up to 50% protection against UV radiation, as measured in our in vitro system, and did not significantly increase sunburn cells in human skin. These results demonstrate the ability of the PHA Gluconolactone to protect against UV radiation-induced elastin promoter activation. In addition, in vivo studies demonstrated that Gluconolactone treatment does not result in a significant increase in sunburn cells. Further investigation of this and other PHAs is necessary to identify their potential role in preventing and repairing cutaneous photodamage.
Christopher Tredwin - One of the best experts on this subject based on the ideXlab platform.
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Anodised TiO2 nanotubes as a scaffold for antibacterial silver nanoparticles on titanium implants
Materials science & engineering. C Materials for biological applications, 2018Co-Authors: Urvashi F. Gunputh, Richard D. Handy, Christopher TredwinAbstract:Abstract Medical grade titanium alloy is widely used for bone/dental implants, but the material alone has no innate antimicrobial properties that would reduce infection risk following surgery. However, silver nanoparticles (Ag NPs) are known to be antibacterial. This study investigated the growth of Ag NPs on titanium dioxide nanotubes (TiO2 NTs) on Ti-6Al-4V discs. The TiO2 NTs were grown on the Ti alloy using an electrochemical method, and then decorated with Ag NPs. The Ag NPs were synthesised by chemical reduction using δ-Gluconolactone. A silver ammonia solution (silver nitrate + liquid ammonia) was used as the source of silver. Two separate approaches were used: (1) The δ-Gluconolactone was mixed with the silver ammonia and then exposed to the TiO2 NTs (the ‘mixing method’), which produced micron-sized clusters of the Ag NPs. (2) The TiO2 NTs were exposed to the silver ammonia first and then to δ-Gluconolactone (the ‘sequential addition method’), which resulted in the formation of nano-sized clusters of the nanoparticles. The Ag-TiO2 composites were confirmed by scanning electron microscopy and the elements analysed using energy dispersive X-ray spectroscopy (EDS). The composite coatings were exposed to a simulated body fluid for 24 h in order to determine the total Ag released. The release from the micron-sized clusters from the mixing method (14.6 ± 0.67 ppm) was higher than that from the nano-sized clusters (4.05 ± 0.36 ppm) when 0.015 M of silver ammonia was used. Additionally, Staphylococcus aureus, was cultured on the composite coatings for 24 h. Both the micron- and nano-sized clusters of the Ag NPs were found to be antibacterial using the Live/Dead assay. Overall, δ-Gluconolactone was successfully used to reduce silver to Ag NPs on the surface of TiO2 NTs. The sequential addition method was the preferred method of synthesis because of its slower silver release, better coverage of the Ag-NPs on the TiO2 NTs and strong antibacterial properties.
Alberto P. Muñuzuri - One of the best experts on this subject based on the ideXlab platform.
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Temporal viscosity modulations driven by a pH sensitive polymer coupled to a pH-changing chemical reaction.
Physical chemistry chemical physics : PCCP, 2017Co-Authors: D. M. Escala, Alberto P. Muñuzuri, A. De Wit, Jorge Carballido-landeiraAbstract:The Formaldehyde-Sulfite (FS) and the Formaldehyde-Sulfite-Gluconolactone (FSG) systems are examples of complex chemical reactions accompanied by well-controlled variations in pH. While the FS system exhibits a clock behavior, in the FSG reaction, this mechanism is coupled with the hydrolysis of the Gluconolactone which gives the possibility to show large temporal oscillations of pH in an open reactor. In this work, we show how these reactive systems, due to their organic nature, can be coupled with pH sensitive polymers, particularly with polyacrylic acid (PAA) to trigger temporal changes of viscosity. We characterize this coupled reactive system showing the effects of changes in the initial concentrations of the polymer and in the chemical reagents on the induction time, the magnitude of the pH variations and the temporal modifications of the viscosity.