Date of Award

6-2008

Document Type

Thesis

Degree Name

Master of Science (MS)

Legacy Department

Materials Science and Engineering

Advisor

Luzinov, Igor

Committee Member

Hirt , Douglas

Committee Member

Lickfield , Gary

Abstract

Tethered polymer chains that are grafted to a solid substrate by one chain end (polymer brushes) may be distinguished from other anchored polymer layers by the relatively high grafting densities gained. Potential uses of polymer brushes for interfacial modification to regulate interactions between proteins and substrates, such as drug delivery and protein separation, are widely recognized. Therefore, it is important to investigate interactions between proteins and surfaces modified with a polymer brush.
In this study, the 'grafting-to' method has been used to graft mixed poly(ethylene glycol) (PEG) and polyacrylic acid (PAA) brushes onto poly(glycidyl methacrylate) (PGMA)-modified silicon wafers/glass slides to create controllable protein adsorption/desorption surfaces. Single component PAA and mixed PEG/PAA brushes exhibit an ionic-strength-dependent height transition, indicating the brush's switching capacity.
Total Internal Reflectance Fluorescence (TIRF) was used to determine the extent of protein adsorption on the PEG, PAA and mixed PEG/PAA brush surfaces. Both high grafting density PEG and PAA brushes repel proteins. The protein adsorption at equilibrium on mixed PEG/PAA brushes surface is affected by PEG grafting density and the number of monomeric units in PAA chains bonded to the surface. The protein adsorption amounts on the mixed brushes are also adjustable when the ionic strength changes. However, the mechanism for protein adsorption and desorption in this mixed polymer brush system needs further investigation.

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