Issue 5, 2011

Mobility of lysozyme inside oxidized starchpolymer microgels

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.

Graphical abstract: Mobility of lysozyme inside oxidized starch polymer microgels

Article information

Article type
Paper
Submitted
10 Sep 2010
Accepted
19 Nov 2010
First published
04 Jan 2011

Soft Matter, 2011,7, 1926-1935

Mobility of lysozyme inside oxidized starch polymer microgels

Y. Li, J. M. Kleijn, M. A. Cohen Stuart, T. Slaghek, J. Timmermans and W. Norde, Soft Matter, 2011, 7, 1926 DOI: 10.1039/C0SM00962H

To request permission to reproduce material from this article, please go to the Copyright Clearance Center request page.

If you are an author contributing to an RSC publication, you do not need to request permission provided correct acknowledgement is given.

If you are the author of this article, you do not need to request permission to reproduce figures and diagrams provided correct acknowledgement is given. If you want to reproduce the whole article in a third-party publication (excluding your thesis/dissertation for which permission is not required) please go to the Copyright Clearance Center request page.

Read more about how to correctly acknowledge RSC content.

Social activity

Spotlight

Advertisements