Molecular diffusivity measurement through an alumina membrane using time-resolved fluorescence imaging

Kennard, Raymond; DeSisto, William J.; Mason, Michael D.

doi:10.1063/1.3518489

Cited by 16 publications

(13 citation statements)

References 13 publications

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“…The release profile observed in this study, and in other studies using nanoporous alumina, nanoporous titanium, oxidized aluminum, and mesoporous silica, is predominantly a burst release. [mt]60% of the loaded drug is released within 20 min, thus diffusion based models, such Peppas‐Korsmeyer, or Higuchi, cannot be applied.…”

Section: Discussionsupporting

confidence: 67%

Reduced oxidative stress in primary human cells by antioxidant released from nanoporous alumina

Pujari-Palmer

Ott

2015

J Biomed Mater Res

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The underlying cause of the selective death of the nigral dopa-minergic neurons in Parkinson's disease is not fully understood. Tetrahydrobiopterin (BH4) is synthesized exclusively in the monoaminergic, including dopaminergic, cells and serves as an endogenous and obligatory cofactor for syntheses of dopamine and nitric oxide. Because BH4 contributes to the syntheses of these two potential oxidative stressors and also undergoes autoxidation, thereby producing reactive oxygen species, it was possible that BH4 may play a role in the selective vulnerability of dopaminergic cells. BH4 given extracellularly was cytotoxic to catecholamine cells CATH.a, SK-N-BE(2)C, and PC12, but not to noncatecholamine cells RBL-2H3, CCL-64, UMR-106-01, or TGW-nu-1. This was not caused by increased dopamine or nitric oxide, because inhibition of their syntheses did not attenuate the damage and BH4 did not raise their cellular levels. Dihydrobiopterin and biopterin were not toxic, indicating that the fully reduced form is responsible. The toxicity was caused by generation of reactive oxygen species, because catalase, superoxide dismutase, and peroxidase protected the cells from the BH4-induced demise. Furthermore, thiol agents, such as reduced glutathione, dithiothreitol,-mer-captoethanol, and N-acetylcysteine were highly protective. The BH4 toxicity was initiated extracellularly, because elevation of intracellular BH4 by sepiapterin did not result in cell damage. BH4 was spontaneously released from the cells of its synthesis to a large extent, and the release was not further enhanced by calcium influx. This BH4-induced cytotoxicity may represent a mechanism by which selective degeneration of dopaminergic terminals and neurons occur.

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Section: Discussionsupporting

confidence: 67%

Reduced oxidative stress in primary human cells by antioxidant released from nanoporous alumina

Pujari-Palmer

Ott

2015

J Biomed Mater Res

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“…Nanoporous ordered structures have gained attention in the last two decades for different applications such as templates for nanoparticles, nanotubes, and nanowires synthesis [ 1 ], but also in devices commonly used in nanofluidics, sensors, or drug delivery applications [ 2 , 3 , 4 , 5 ]. Silica, alumina, or titania nanotubular structures with regular pore diameters and interpore distances can be used as models systems for fluid transport [ 6 , 7 , 8 , 9 ].…”

Section: Introductionmentioning

confidence: 99%

“…In fact, the effect on the diffusive transport through nanopores of the electrical membrane-solute (charged molecules or ions) interactions related with the pore surface material as well as its dependence on the pore size and porosity have already been revealed [ 14 ]. Moreover, other effects able to affect the diffusive transport of charged molecules and ions such as concentration polarization or the Donnan exclusion effect, this latter in the case of charged solids/electrolyte solutions, should also be considered since they could explain the extremely reduced diffusivity values through nanoporous membranes obtained from indirect measurements (time-resolved fluorescence imaging [ 4 ], decoloration by photometric measurements [ 15 ], etc. ).…”

Section: Introductionmentioning

confidence: 99%

Morphological, Chemical Surface, and Diffusive Transport Characterizations of a Nanoporous Alumina Membrane

et al. 2015

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Synthesis of a nanoporous alumina membrane (NPAM) by the two-step anodization method and its morphological and chemical surface characterization by analyzing Scanning Electron Microscopy (SEM) micrographs and X-Ray Photoelectron Spectroscopy (XPS) spectra is reported. Influence of electrical and diffusive effects on the NaCl transport across the membrane nanopores is determined from salt diffusion measurements performed with a wide range of NaCl concentrations, which allows the estimation of characteristic electrochemical membrane parameters such as the NaCl diffusion coefficient and the concentration of fixed charges in the membrane, by using an appropriated model and the membrane geometrical parameters (porosity and pore length). These results indicate a reduction of ~70% in the value of the NaCl diffusion coefficient through the membrane pores with respect to solution. The transport number of ions in the membrane pores (Na+ and Cl−, respectively) were determined from concentration potential measurements, and the effect of concentration-polarization at the membrane surfaces was also considered by comparing concentration potential values obtained with stirred solutions (550 rpm) and without stirring. From both kinds of results, a value higher than 0.05 M NaCl for the feed solution seems to be necessary to neglect the contribution of electrical interactions in the diffusive transport.

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“…Note that some of the proposed mechanisms, for example, increased viscosity of solvents in a pore large than several nanometers, have been under debate for a long time. Some argue that the unusually large viscosity can only extend to ∼1 nm scale into the solution, , while others suggest that long-range interfacial effect has been observed and the microenvironment in pores as large as tens to hundreds of nanometers can be significantly different than in bulk solution. − …”

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confidence: 99%

Microscopic Movement of Slow-Diffusing Nanoparticles in Cylindrical Nanopores Studied with Three-Dimensional Tracking

et al. 2016

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To study slow mass transport in confined environments, we developed a three-dimensional (3D) single-particle localization technique to track their microscopic movements in cylindrical nanopores. Under two model conditions, particles are retained much longer inside the pores: (1) increased solvent viscosity, which slows down the particle throughout the whole pore, and (2) increased pore wall affinity, which slows down the particle only at the wall. In viscous solvents, the particle steps decrease proportionally to the increment of the viscosity, leading to macroscopically slow diffusion. As a contrast, the particles in sticky pores are microscopically active by showing limited reduction of step sizes. A restricted diffusion mode, possibly caused by the heterogeneous environment in sticky pores, is the main reason for macroscopically slow diffusion. This study shows that it is possible to differentiate slow diffusion in confined environments caused by different mechanisms.

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Molecular diffusivity measurement through an alumina membrane using time-resolved fluorescence imaging

Cited by 16 publications

References 13 publications

Reduced oxidative stress in primary human cells by antioxidant released from nanoporous alumina

Reduced oxidative stress in primary human cells by antioxidant released from nanoporous alumina

Morphological, Chemical Surface, and Diffusive Transport Characterizations of a Nanoporous Alumina Membrane

Microscopic Movement of Slow-Diffusing Nanoparticles in Cylindrical Nanopores Studied with Three-Dimensional Tracking

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