Protein adsorption on and swelling of polyelectrolyte brushes: A simultaneous ellipsometry-quartz crystal microbalance study

Leibniz Institute of Polymer Research Dresden, Hohe Str. 6, 1069 Dresden, Germany.
Biointerphases (Impact Factor: 3.37). 12/2010; 5(4):159-67. DOI: 10.1116/1.3530841
Source: PubMed


With a coupled spectroscopic ellipsometry-quartz crystal microbalance with dissipation (QCM-D) experimental setup, quantitative information can be obtained about the amount of buffer components (water molecules and ions) coupled to a poly(acrylic acid) (PAA) brush surface in swelling and protein adsorption processes. PAA Guiselin brushes with more than one anchoring point per single polymer chain were prepared. For the swollen brushes a high amount of buffer was found to be coupled to the brush-solution interface in addition to the content of buffer inside the brush layer. Upon adsorption of bovine serum albumin the further incorporation of buffer molecules into the protein-brush layer was monitored at overall electrostatic attractive conditions [below the protein isolectric poimt (IEP)] and electrostatic repulsive conditions (above the protein IEP), and the shear viscosity of the combined polymer-protein layer was evaluated from QCM-D data. For adsorption at the "wrong side" of the IEP an incorporation of excess buffer molecules was observed, indicating an adjustment of charges in the combined polymer-protein layer. Desorption of protein at pH 7.6 led to a very high stretching of the polymer-protein layer with additional incorporation of high amounts of buffer, reflecting the increase of negative charges on the protein molecules at this elevated pH.

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Available from: Keith B Rodenhausen, Dec 13, 2013
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    • "Moreover, QCM-D is highly sensitive for studying dynamic adsorption processes and it gives insight into the characteristics and structure of adsorbed layer [29] [30]. Bittrich et al. studied the adsorption of BSA onto polyelectrolyte brushes above and below the protein isoelectric point [31]. They proved that viscoelastically coupled buffer molecules were released from the interface between proteins and swelling polyelectrolyte brush and concluded an adjustment of charges and possibly charge distribution in the combined polymer-protein layer. "
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