Download or read book The Effect of Solute Concentration on the Equilibrium Partitioning and Hindered Gradient Diffusion of Colloids in Polymeric Hydrogels written by Kristan Kay-Schurle Buck and published by . This book was released on 2000 with total page 436 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solute Partitioning and Hindered Diffusion in Hydrogels written by David Ezra Liu and published by . This book was released on 2016 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt: Solute uptake and release govern the efficacy of hydrogels in controlled drug delivery, tissue engineering, and chromatographic separations. In soft contact lenses, uptake and release of wetting, packaging, and care-solution agents is extensively employed to improve on-eye lens performance. Key physical parameters are the equilibrium solute partition coefficient and the solute diffusion coefficient in the gel that dictate the amounts and rates of uptake/release, respectively. To investigate the mechanisms of solute uptake and release in hydrogels, this work experimentally and theoretically determines equilibrium partition and diffusion coefficients of prototypical macromolecules and drugs in hydrogels over a wide range of water contents. A hydrogel is a crosslinked polymer network with water-filled voids arranged in an unstructured three-dimensional mesh. Solutes (e.g., drugs, sugars, proteins, polymers) typically partition into and diffuse through the water-filled mesh but are excluded from mesh voids smaller than solute size. Consequently, solute size and the distribution of mesh sizes in the hydrogel-polymer network are vital to understand solute uptake and release. Solutes may also exhibit specific interactions with and, accordingly, adsorb to hydrogel polymer chains by hydrogen bonding or counterion binding. Specific solute adsorption to hydrogel-polymer strands results in larger partition coefficients and diminished effective diffusion rates. To elucidate size effects on aqueous-solute transport rates, diffusion coefficients of large macromolecules in hydrogels with relatively small mesh sizes are investigated experimentally and theoretically. Two photon-confocal microscopy measures transient uptake and release concentration profiles of fluorescently labeled dextrans of varying molecular weight, and fluorescently labeled cationic avidin protein. Dextrans are highly water-soluble polysaccharides. Consequently, they exhibit negligible specific interactions with the hydrogel polymer network. Hydrogel uptake and release follow Fick's second law with almost identical diffusion coefficients in the uptake and release directions. To interpret our data, we implement a Large Pore Effective Medium (LPEM) model taking into account hydrodynamic drag, steric obstruction, and the distribution of mesh sizes available for solute transport. All necessary parameters are measured independently. In all cases, a priori- predicted diffusion coefficients by LPEM theory display excellent agreement with experiment. In contrast to the nonspecific interacting dextrans, cationic avidin protein exhibits near irreversible adsorption with incomplete loading even after 6 days and incomplete release even after two weeks. Avidin protein uptake and release rates clearly highlight the significance of solute-specific adsorption in understanding solute transport rates in hydrogels. Despite its importance, little attention has been given to how solute-specific interactions affect solute uptake in and release from hydrogels. We measure and theoretically predict partition and diffusion coefficients for prototypical water-soluble drugs in hydrogels where solute-specific binding is pronounced. Hydrogel composition is varied by adjusting the ratio of monomer constituents, 2-hydroxyethyl methacrylate (HEMA) and methacrylic acid (MAA). Partition and diffusion coefficients are obtained through two-photon confocal microscopy and UV/Vis-absorption spectrophotometry upon back extraction. The studied prototypical drugs all exhibit specific adsorption to nonionic MAA and HEMA moieties characterized by greater-than-unity partition coefficients and smaller effective diffusion rates. Conversely, none of the prototypical drugs displayed specific interactions with anionic MAA moieties. To predict equilibrium partition coefficients, we express the partition coefficient as a product of the hydrogel water content and individual enhancement factors for size-exclusion, nonspecific electrostatic interactions, and specific adsorption. Again, all necessary parameters are obtained independently. To predict effective diffusion coefficients, we extend LPEM for specific-solute adsorption and impose local equilibrium. As with the non-interacting dextran solutes, predicted partition and diffusion coefficients are in good agreement with experiment. A framework is now available to predict solute partitioning and diffusion in solute-hydrogel systems that exhibit specific interactions. The developed theories for solute partitioning are further extended for direct application to silicone-hydrogel contact-lens materials. Silicone hydrogels (SiHy) are microphase-separated materials with silicone domains for oxygen transport and hydrophilic-polymer domains for aqueous-solute transport. Equilibrium silicone-hydrogel water and solute uptake are measured and predicted with an extended partitioning theory assuming that water and aqueous solutes reside only in the hydrophilic-polymer phase, whereas oleophilic solutes partition primarily into the silicone microphase. Excellent agreement is found between theory and experiment. Significantly, our development provides estimation of partitioning properties in silicone hydrogels based solely on synthesis formulation chemistry. Finally, we deduce compositional properties of a laminated soft contact lens, DAILIES TOTAL 1® (delefilcon A) through measurement of fluorescent solute partition coefficients. Measured partition coefficients and solute-partitioning theory establish (1) the silicone-hydrogel core of the laminated lens is structurally similar to that of a non-laminated commercial SiHy soft contact lens, O2OPTIXTM, (2) the laminated-lens surface-gel layers are ~10 μm in thickness, (3) the laminated-lens surface-gel layers are of higher water content than the core, and (4) the surface-gel layers of the laminated lens are anionic, whereas the core is nonionic. Importantly, with solute-uptake properties known, our proposed solute-partitioning theory provides a means to elucidate hydrogel physico-chemical properties.
Download or read book The Effect of Solute Concentration on Hindered Gradient Diffusion in Polymeric Gels written by Kristan K. S. Buck and published by . This book was released on 1999 with total page 66 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Effect of Solute Concentration on Equilibrium Partitioning in Polymeric Gels written by Kristan K. S. Buck and published by . This book was released on 2000 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2001 with total page 834 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Polymeric and Self Assembled Hydrogels written by Xian Jun Loh and published by Royal Society of Chemistry. This book was released on 2013 with total page 275 pages. Available in PDF, EPUB and Kindle. Book excerpt: The only book to give a complete picture of current hydrogel research, covering all the major applications as well as the fundamental principles behind them.
Download or read book Hydrogels in Cell based Therapies written by Che J. Connon and published by Royal Society of Chemistry. This book was released on 2014-04-08 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Leading experts provide a comprehensive overview of recent progress in the synthesis of different hydrogels and their biomedical applications.
Download or read book Emerging Concepts in Analysis and Applications of Hydrogels written by Sutapa Biswas Majee and published by BoD – Books on Demand. This book was released on 2016-08-24 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is an Up-to-date and authoritative account on physicochemical principles, pharmaceutical and biomedical applications of hydrogels. It consists of eight contributions from different authors highlighting properties and synthesis of hydrogels, their characterization by various instrumental methods of analysis, comprehensive review on stimuli-responsive hydrogels and their diverse applications, and a special section on self-healing hydrogels. Thus, this book will equip academia and industry with adequate basic and applied principles related to hydrogels.
Download or read book Functional Hydrogels in Drug Delivery written by Umile Gianfranco Spizzirri and published by CRC Press. This book was released on 2017-08-10 with total page 362 pages. Available in PDF, EPUB and Kindle. Book excerpt: The book deals with the synthesis and characterization of hydrogels specifically used as drug delivery systems. Each chapter includes the most recent updates about the different starting materials employed and the improvement of their physicochemical and biological properties to synthetize high performing carriers for specific uses.
Download or read book Stimuli Responsive Gels written by Dirk Kuckling and published by MDPI. This book was released on 2018-10-11 with total page 289 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is a printed edition of the Special Issue "Stimuli-Responsive Gels" that was published in Gels
Download or read book The Effect of Solute Concentration on the Hindered Diffusion of Dextran and Polyethylene Glycol in Porous Membranes written by Jiahui Shao and published by . This book was released on 2000 with total page 366 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Synthesis of Novel Hydrogels with Unique Mechanical Properties written by Yi Cao and published by Frontiers Media SA. This book was released on 2020-12-23 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: This eBook is a collection of articles from a Frontiers Research Topic. Frontiers Research Topics are very popular trademarks of the Frontiers Journals Series: they are collections of at least ten articles, all centered on a particular subject. With their unique mix of varied contributions from Original Research to Review Articles, Frontiers Research Topics unify the most influential researchers, the latest key findings and historical advances in a hot research area! Find out more on how to host your own Frontiers Research Topic or contribute to one as an author by contacting the Frontiers Editorial Office: frontiersin.org/about/contact.
Download or read book Hydrogels written by Thakur Raghu Raj Singh and published by CRC Press. This book was released on 2018-02-28 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: Hydrogels are crosslinked, macromolecular polymeric materials arranged in a three-dimensional network, which can absorb and retain large amounts of water. Hydrogels are commonly used in clinical practice and experimental medicine for a wide range of applications, including drug delivery, tissue engineering and regenerative medicine, diagnostics, cellular immobilization, separation of biomolecules or cells, and barrier materials to regulate biological adhesions. This book elucidates the underlying concepts and emerging applications of hydrogels and will provide key case studies and critical analysis of the existing research.
Download or read book Polymeric Stabilization of Colloidal Dispersions written by Donald H. Napper and published by . This book was released on 1983 with total page 456 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hindered Diffusion of Micelles in Agarose Gels written by Donna Dan Kong and published by . This book was released on 2004 with total page 188 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Solute Partitioning in Hydrogels written by Meghan E. Lund and published by . This book was released on 1995 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Diffusiophoretic transport of colloidal particles in nonionic polymer solute gradients written by Aditya Ranjan Das and published by . This book was released on 1989 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
