Article

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: 1.91). 12/2010; 5(4):159-67. DOI: 10.1116/1.3530841
Source: PubMed

ABSTRACT 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.

0 Bookmarks
 · 
135 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: QCM-D technique is based on the physical phenomenon that generates an acoustic shear wave with an oscillating resonance in quartz resulting in an evanescent wave that arises at the interface of the quartz and the solution. The amplitude of the acoustic wave is influenced by the deposition of material onto the quartz surface and from the subsequent decrease of the frequency the bound mass can be calculated. The dissipation shift which arises inform about viscoelasticity and flexibility of the adsorbed material. QCM-D can be applied for real-time studies of several biological systems since it is a simple, fast, low-cost and sensitive technique without having to label any sample. Common applications in biological field include measurements on adsorption of lipids, proteins, DNA and cells directly onto the surface of the sensor, which generally are chemically modified by self-assembled monolayer (SAM) technique or by spin-coated polymers. QCM-D can also be used to study molecular interactions between macromolecules and adsorbed materials. Three examples of the use of this technique are presented, namely the docking orientation of the C2 domain of PKCε on phospholipid membranes, the conformational changes of fibrinogen adsorbed to model acrylic polymers and the attachment of endothelial cells to carboxylated polymers of different configuration.
    Biomedical spectroscopy and imaging. 12/2012; 1(4):325-38.
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Protein adsorption is a dynamic process and plays a major role in determining the hemocompatibility of biomaterials. We have obtained different poly (ethylene glycol) (PEG) graft concentrations of SEBS-g-PEG and the surface chemical compositions are confirmed by X-ray photoelectron spectroscopy (XPS). Graft concentration is defined by peak-area ratio of [C--O]/[C] on modified SEBS surface. With increasing graft concentration, water contact angles of the modified SEBS have significantly decreased. The platelet adhesion and static protein adsorption demonstrate that the hemocompatibility of copolymers films are improved effectively and SEBS-g-PEG-2 with larger graft concentration has more superior anticoagulation than that of SEBS-g-PEG-1. Moreover, we have quantitatively investigated the adsorption process of bovine serum albumin (BSA) and fibrinogen (Fib) on the surfaces of pristine SEBS and modified SEBS using quartz crystal microbalance with dissipation (QCM-D) in real time. The results indicate that the inactivated BSA on the pristine SEBS can continuously induce the subsequent Fib adsorption. The hemocompatibility of SEBS-g-PEG-2 with the graft concentration of 0.207 has excellent anti-protein property and the bio-inert BSA layer on the film can resist the subsequent Fib adsorption.
    Applied Surface Science 04/2014; 301. · 2.54 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The great wealth of different surface sensitive techniques used in biosensing, most of which claim to measure adsorbed mass, can at first glance look unnecessary. However, with each technique relying on a different transducer principle there is something to be gained from a comparison. In this tutorial review, different optical and acoustic evanescent techniques are used to illustrate how an understanding of the transducer principle of each technique can be exploited for further interpretation of hydrated and extended polymer and biological films. Some of the most commonly used surface sensitive biosensor techniques (quartz crystal microbalance, optical waveguide spectroscopy and surface plasmon resonance) are briefly described and five case studies are presented to illustrate how different biosensing techniques can and often should be combined. The case studies deal with representative examples of adsorption of protein films, polymer brushes and lipid membranes, and describe e.g., how to deal with strongly vs. weakly hydrated films, large conformational changes and ordered layers of biomolecules. The presented systems and methods are compared to other representative examples from the increasing literature on the subject.
    Biosensors. 12/2012; 2(4):341-376.

Full-text (2 Sources)

Download
30 Downloads
Available from
May 30, 2014