Solute diffusion in swollen membranes

Harland, Ronald S.; Peppas, Nikolaos A.

doi:10.1007/bf00255341

Cited by 20 publications

(10 citation statements)

References 3 publications

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“…To account for the results shown in Figure 4, we next quantified the accessibility of the dsDNA matrices to enzymes using the Peppas model 24 , which is widely used to describe the diffusion of solutes within polymeric matrices. In particular, we calculated the hindrance-free mesh width (ξ) as a function of the matrix height IH, associated with the enzyme diffusion in parallel (ξ SW , solid line in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…similar to the enzyme top entry, the enzyme top exit is likely hindered by the rotationally diffusing dsDnAs. To calculate the hindrance-free mesh width (see dashed circle) associated with the dsDnA matrix along the direction parallel to the surface (ξ sW ) 24 , we modelled the effect of non-negligible, lateral collisions between 2D-diffusing enzyme and dsDnAs inside the matrix by reducing the maximum tilt angle of the latter to θ sW = cos − 1 [(1/θ max )·sin(θ max )] < θ max . In turn, ξ sW is defined as the diameter of the circle inscribed between two adjacent rods tilted at θ sW (see dashed circle in e).…”

Section: Resultsmentioning

confidence: 99%

“…Furthermore, according to this mechanism, enzymes gain access at the sides of the dsDNA matrix through an area that is 1,000-fold smaller than the total dsDNA matrix-liquid interface. We explain these results by modelling the steric hindrance on the dsDNA matrix-liquid interface, and propose a semiquantitative, steric hindrance-dependent enzyme access mechanism that is inspired by an established model that describes the diffusion of solutes inside polymer matrices 24 .…”

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Two-dimensional enzyme diffusion in laterally confined DNA monolayers

et al. 2011

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Addressing the effects of confinement and crowding on biomolecular function may provide insight into molecular mechanisms within living organisms, and may promote the development of novel biotechnology tools. Here, using molecular manipulation methods, we investigate restriction enzyme reactions with double-stranded (ds)DnA oligomers confined in relatively large (and flat) brushy matrices of monolayer patches of controlled, variable density. We show that enzymes from the contacting solution cannot access the dsDnAs from the topmatrix interface, and instead enter at the matrix sides to diffuse two-dimensionally in the gap between top-and bottom-matrix interfaces. This is achieved by limiting lateral access with a barrier made of high-density molecules that arrest enzyme diffusion. We put forward, as a possible explanation, a simple and general model that relates these data to the steric hindrance in the matrix, and we briefly discuss the implications and applications of this strikingly new phenomenon.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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confidence: 99%

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Two-dimensional enzyme diffusion in laterally confined DNA monolayers

et al. 2011

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“…Schuszter et al calculated hydronium ion diffusivity in agarose hydrogels within the same order of magnitude. A reduction in hydronium effective diffusivity relative to pure water may be explained by physical obstruction by polymer domains within the hydrogel including impermeable crystalline regions. , Polymer chains, which make up the hydrogel structure, act as road blocks to diffusing species as they move between water domains. Two physical parameters which may exacerbate obstruction within the hydrogel are polymer mass fraction and crystallinity.…”

Section: Resultsmentioning

confidence: 99%

Investigation of Hydronium Diffusion in Poly(vinyl alcohol) Hydrogels: A Critical First Step to Describe Acid Transport for Encapsulated Bioremediation

et al. 2022

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Bioremediation of chlorinated aliphatic hydrocarbon-contaminated aquifers can be hindered by high contaminant concentrations and acids generated during remediation. Encapsulating microbes in hydrogels may provide a protective, tunable environment from inhibiting compounds; however, current approaches to formulate successful encapsulated systems rely on trial and error rather than engineering approaches because fundamental information on mass-transfer coefficients is lacking. To address this knowledge gap, hydronium ion mass-transfer rates through two commonly used hydrogel materials, poly(vinyl alcohol) and alginic acid, under two solidification methods (chemical and cryogenic) were measured. Variations in hydrogel crosslinking conditions, polymer composition, and solvent ionic strength were investigated to understand how each influenced hydronium ion diffusivity. A three-way ANOVA indicated that the ionic strength, membrane type, and crosslinking method significantly (p < 0.001) contributed to changes in hydronium ion mass transfer. Hydronium ion diffusion increased with ionic strength, counter to what is observed in aqueous-only (no polymer) solutions. Co-occurring mechanisms correlated to increased hydronium ion diffusion with ionic strength included an increased water fraction within hydrogel matrices and hydrogel contraction. Measured diffusion rates determined in this study provide first principal design information to further optimize encapsulating hydrogels for bioremediation.

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“…These have been reviewed from time to time by several researchers. [19][20][21][22][23][24][25][26][27][28][29][30][31][32] However, there is no single model that successfully predicts all possible experimental conditions. Nevertheless, collectively they can contribute towards the elucidation of the mechanism involved.…”

Section: Modeling Repellent Releasementioning

confidence: 99%

Development, characterization and modeling of mosquito repellent release from microporous devices

et al. 2020

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Nanocomposite strands with mosquito repellent DEET or Icaridin incorporated in a poly(ethylene-co-vinyl acetate) (EVA) matrix, with either pyrogenic silica or an organoclay as a nanofiller, were prepared by a twin-screw extrusion compounding technique. The nature and levels of the repellent and nanofiller that was used affected the material phase morphology. The repellent release was followed as a function of aging time in convection ovens set at 30 and 50 C. The experimental release data of the mosquito repellent from the microporous polymer swellable matrix strands was mathematically modeled and fitted using a range of semi-empirical models. In the majority of case, the Korsmeyer-Peppas power law model provided the best data fit. As expected, the wide range of internal morphologies also resulted in quite different release profiles. These models were found to be valuable as they provided insights into the mechanism of repellent release from EVA swellable matrices. It was possible to differentiate between diffusion and relaxation mechanisms. Surprisingly, strands containing nominally more than 30 wt% Icaridin showed accelerating mass loss during the initial phase, consistent with Super Case II transport. Diffusional exponents as high as 1.81 were found. Furthermore, the internal microporous region of the extruded EVA strands was covered by a surface membrane that acted a diffusion barrier that, in effect, controlled the release rate of the mosquito repellents. Some of the investigated samples exhibited release profiles that suggest that longer lasting effective release of repellents is possible than currently achieved by available commercially products. K E Y W O R D S controlled release, microporous system, modeling, repellent 1 | INTRODUCTION Collectively, the mosquito-borne diseases of malaria, Dengue, Yellow fever, O'nyong-nyong fever, Zika and lymphatic filariasis (elephantiasis) are the single biggest cause of morbidity and mortality in humans. These mosquito-transmitted infections occur at the global scale and involve a wide range of viral and other pathogenic

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Solute diffusion in swollen membranes

Cited by 20 publications

References 3 publications

Two-dimensional enzyme diffusion in laterally confined DNA monolayers

Two-dimensional enzyme diffusion in laterally confined DNA monolayers

Investigation of Hydronium Diffusion in Poly(vinyl alcohol) Hydrogels: A Critical First Step to Describe Acid Transport for Encapsulated Bioremediation

Development, characterization and modeling of mosquito repellent release from microporous devices

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