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- Mattisson, C, et al.
(author)
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Diffusion of lysozyme in gels and liquids - A general approach for the determination of diffusion coefficients using holographic laser interferometry
- 2000
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In: Journal of Chromatography. B. - 1387-2273. ; 743:1-2, s. 151-167
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Journal article (peer-reviewed)abstract
- A study on diffusion measurements of the protein lysozyme in liquids and agarose gels, at different pH and ionic strengths, has been performed using holographic laser interferometry. The measurements showed that the diffusive flux was very dependent on pH and ionic strength when the protein was not at its isoelectric point or when the charge of the lysozyme molecules was not screened by ions in the solution. Evaluation of the experimental data with Fick's law, resulted in diffusion coefficients for lysozyme that are strongly dependent on pH and ionic strength. Evaluation of the experimental data using a more general transport model, based on chemical potential gradients instead of concentration gradients resulted in lysozyme diffusion coefficients that are independent of pH and ionic strength. The chemical potential was estimated by using the Poisson-Boltzmann equation. (C) 2000 Elsevier Science B.V. All rights reserved.
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- Roger, P, et al.
(author)
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Use of holographic laser interferometry to study the diffusion of polymers in gels
- 2000
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In: Biotechnology and Bioengineering. - 1097-0290. ; 69:6, s. 654-663
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Journal article (peer-reviewed)abstract
- The aim of this study was to demonstrate the potential for holographic interferometry to be used for diffusion studies of large molecules in gels. The diffusion and partitioning of BSA (67,000 g/mol) and pullulans (5,900-112,000 g/mol) in agarose gel were investigated. The gel diffusion coefficients obtained for BSA were higher when distilled water was used as a solvent compared to those obtained with 0.1 M NaCl as the solvent. Furthermore, the gel diffusion coefficient increased with increasing BSA concentration. The same trend was found for liquid BSA diffusion coefficients obtained by DLS. BSA partition coefficients obtained at different agarose gel concentrations (2-6%, w/w) decreased slightly with increasing gel concentration. However, all BSA gel diffusion coefficients measured were significantly lower than those in pure solvent and they decreased with increasing agarose concentration. The gel diffusion coefficients obtained for pullulans decreased with increasing pullulan molecular weight. The same effect from increased molecular weight was seen in the liquid diffusion coefficients measured by DLS. The pullulan partition coefficients obtained decreased with increasing molecular weight. However, pullulans with a larger Stokes' radius than BSA had partition coefficients that were higher or approximately the same as BSA. This implied that the pullulan molecules were more flexible than the BSA molecules. The results obtained for BSA in this study agreed well with other experimental studies. In addition, the magnitude of the relative standard deviation was acceptable and in the same range as for many other methods. The results thereby obtained showed that holographic interferometry is a suitable method for studying diffusion of macromolecules in gels. (C) 2000 John Wiley & Sons, Inc.
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