Staff Publications

Staff Publications

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    'Staff publications' is the digital repository of Wageningen University & Research

    'Staff publications' contains references to publications authored by Wageningen University staff from 1976 onward.

    Publications authored by the staff of the Research Institutes are available from 1995 onwards.

    Full text documents are added when available. The database is updated daily and currently holds about 240,000 items, of which 72,000 in open access.

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Record number 411042
Title Mobility of lysozyme inside oxidized starch polymer microgels
Author(s) Li, Y.; Kleijn, J.M.; Cohen Stuart, M.A.; Slaghek, T.; Timmermans, J.; Norde, W.
Source Soft Matter 7 (2011)5. - ISSN 1744-683X - p. 1926 - 1935.
DOI https://doi.org/10.1039/c0sm00962h
Department(s) Physical Chemistry and Colloid Science
VLAG
Publication type Refereed Article in a scientific journal
Publication year 2011
Keyword(s) poly(acrylic acid) microgels - glucose-responsive microgels - drug-delivery - diffusion - hydrogels - proteins - release - ph - encapsulation - temperature
Abstract The aim of this paper is to determine the mobility of protein molecules inside oxidized potato starch polymer (OPSP) microgel particles (spherical, 10–20 µm in diameter). This provides relevant information for controlled uptake and release applications of such systems. The mobility of Alexa-488 labelled lysozyme inside the microgel is measured by fluorescence recovery after photobleaching (FRAP) in combination with confocal laser scanning microscopy (CLSM). CLSM images show that the protein molecules distribute quite homogeneously over the microgel particles. By fitting the FRAP data with a model based on exchange between bleached and unbleached protein molecules inside the gel, we identified several protein fractions of different mobility. Increasing the salt concentration (NaCl) or the pH causes a shift in the distribution towards the more mobile fractions. This is consistent with earlier uptake and release measurements, which showed that the binding affinity decreases with increasing salt concentration and pH. At low protein concentrations, at which the microgel is not saturated with protein, the mobility of the bound protein molecules is more restricted than at protein concentrations where the uptake is complete. This is attributed to binding of the protein molecules to multiple binding sites. The model explains reasonably the mechanism of protein mobility inside the microgel, indicating that embedded ingredients with charge properties comparable to those of lysozyme can be protected at low salt concentration and low pH. Increasing the salt concentration or the pH triggers the release
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