Solute Diffusion within Hydrogels. Mechanisms and Models

Amsden, Brian G.

doi:10.1021/ma980765f

Cited by 825 publications

(860 citation statements)

References 55 publications

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“…49 Moreover, in line with our release kinetics from the hydrophilic gel compartments, where diffusion coefficients of BSA varying from 1.1 to 52.9 µm 2 /sec were found (Figures 3SI-A and 4SI-A, Supporting Information), a range of Ds from 8.5 to 45.4 µm 2 /sec were obtained for hyaluronic acid/Pluronic hydrogels. 48 The diffusion coefficients based on release experiments from the highly cross-linked hydrophobic domains, ranging between 0.01 and 3.5 µm 2 /sec ( Figures 3SI-B and 4SI-B, Supporting Information), were comparable to the ones published for photocross-linked low molecular weight PEG hydrogels.…”

Section: Resultssupporting

confidence: 83%

Photopolymerized Thermosensitive Poly(HPMAlactate)-PEG-Based Hydrogels: Effect of Network Design on Mechanical Properties, Degradation, and Release Behavior

et al. 2010

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Photopolymerized thermosensitive A-B-A triblock copolymer hydrogels composed of poly(N-(2-hydroxypropyl)-methacrylamide lactate) A-blocks, partly derivatized with methacrylate groups to different extents (10, 20, and 30%) and hydrophilic poly(ethylene glycol) B-blocks of different molecular weights (4, 10, and 20 kDa) were synthesized. The aim of the present study was to correlate the polymer architecture with the hydrogel properties, particularly rheological, swelling, degradation properties and release behavior. It was found that an increasing methacrylation extent and a decreasing PEG molecular weight resulted in increasing gel strength and cross-link density, which tailored the degradation profiles from 25 to more than 300 days. Polymers having small PEG blocks showed a remarkable phase separation into polymer-and water-rich domains, as demonstrated by confocal microscopy. Depending on the hydrophobic domain density, the loaded protein resides in the hydrophilic pores or is partitioned into hydrophilic and hydrophobic domains, and its release from these compartments is tailored by the extent of methacrylation and by PEG length, respectively. As the mechanical properties, degradation, and release profiles can be fully controlled by polymer design and concentration, these hydrogels are suitable for controlled protein release.

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Section: Resultssupporting

confidence: 83%

Photopolymerized Thermosensitive Poly(HPMAlactate)-PEG-Based Hydrogels: Effect of Network Design on Mechanical Properties, Degradation, and Release Behavior

et al. 2010

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“…Furthermore, the model of Phillips was found to give better agreement with experimental values for large solutes ( > ) which are not the conditions of our systems (Amsden, 1998).…”

Section: Discussionsupporting

confidence: 48%

Controlled drug release from hydrogels for contact lenses: Drug partitioning and diffusion

Pimenta

Ascenso

Fernandes

et al. 2016

International Journal of Pharmaceutics

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Optimization of drug delivery from drug loaded contact lenses assumes understanding the drug transport mechanisms through hydrogels which relies on the knowledge of drug partition and diffusion coefficients. We chose, as model systems, two materials used in contact lens, a poly-hydroxyethylmethacrylate (pHEMA) based hydrogel and a silicone based hydrogel, and three drugs with different sizes and charges: chlorhexidine, levofloxacin and diclofenac. Equilibrium partition coefficients were determined at different ionic strength and pH, using water (pH 5.6) and PBS (pH 7.4). The measured partition coefficients were related with the polymer volume fraction in the hydrogel, through the introduction of an enhancement factor following the approach developed by the group of C. J. Radke (Kotsmar et al., 2012;Liu et al., 2013). This factor may be decomposed in the product of three other factors , and which account for, respectively, hard-sphere size exclusion, electrostatic interactions, and specific solute adsorption. While and are close to 1, >>1 in all cases suggesting strong specific interactions between the drugs and the hydrogels. Adsorption was maximal for chlorhexidine on the silicone based hydrogel, in water, due to strong hydrogen bonding.The effective diffusion coefficients, , were determined from the drug release profiles.Estimations of diffusion coefficients of the non-adsorbed solutes = × allowed comparison with theories for solute diffusion in the absence of specific interaction with the polymeric membrane.

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“…Many physical models have been developed to model the diffusion of small solutes in hydrogels [18,19].…”

Section: Review Of Experimental and Theoretical Studies Of Hydrogelsmentioning

confidence: 99%

Effect of Cross-Linking on the Diffusion of Water, Ions, and Small Molecules in Hydrogels

2009

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Understanding the diffusion of small molecules in hydrogel system is of major importance in a variety of applications including drug delivery systems, tissue engineering and contact lens. Cross-linking density of hydrogels has been commonly used to tune key parameters like mesh size and molecular weight between cross-linkers, in order to change macroscopic properties of hydrogels. In this thesis, molecular dynamics investigations of chemically-cross-linked poly(ethylene glycol) (PEG) hydrogels are reported with the aim of exploring the diffusion properties of water, ions, and rhodamine within the polymer at the molecular level.The water structure and diffusion properties were studied at various cross-linking densities with molecular weights of the chains ranging from 572 to 3400. As the cross-linking density is increased, the water diffusion decreases and the slowdown in diffusion is more severe at the polymer-water interface. The water diffusion at various cross-linking densities is correlated with the water hydrogen bonding dynamics. The diffusion of ions and rhodamine also decreased as the cross-linking density is increased. The variation of diffusion coefficient with cross-linking density is related to the variation of water content at different cross-linking densities.Comparison of simulation results and obstruction scaling theory for hydrogels showed similar trends.ii To Father and Mother.iii

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Solute Diffusion within Hydrogels. Mechanisms and Models

Cited by 825 publications

References 55 publications

Photopolymerized Thermosensitive Poly(HPMAlactate)-PEG-Based Hydrogels: Effect of Network Design on Mechanical Properties, Degradation, and Release Behavior

Photopolymerized Thermosensitive Poly(HPMAlactate)-PEG-Based Hydrogels: Effect of Network Design on Mechanical Properties, Degradation, and Release Behavior

Controlled drug release from hydrogels for contact lenses: Drug partitioning and diffusion

Effect of Cross-Linking on the Diffusion of Water, Ions, and Small Molecules in Hydrogels

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