AVS 51st International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI-WeA

Paper BI-WeA6
Stable Protein-resistant Surfaces: Covalent Immobilization of Poly(L-Lysine)-g-Poly(Ethylene Glycol) onto Plasma-modified, Aldehyde-activated Substrate Surfaces

Wednesday, November 17, 2004, 3:40 pm, Room 210D

Session: "Passive" and Non-Fouling Surfaces
Presenter: T.M. Blättler, Swiss Federal Institute of Technology, Switzerland
Authors: T.M. Blättler, Swiss Federal Institute of Technology, Switzerland
S. Pasche, Swiss Federal Institute of Technology, Switzerland
M. Textor, Swiss Federal Institute of Technology, Switzerland
H.J. Griesser, University of South Australia
Correspondent: Click to Email
The fabrication of protein resistant surfaces is of considerable interest for a number of applications. Electrostatically adsorbed PEGylated graft copolymers, such as poly(L-lysine)-g-poly(ethylene glycol) (PLL-g-PEG), have been very successful in reducing protein adsorption on negatively charged metal oxide surfaces. The drawback is their instability under extreme conditions (extreme pH or high ionic strength). We have overcome this limitation in the present work by covalently immobilizing PLL-g-PEG onto aldehyde plasma modified substrates. PLL-g-PEG was immobilized on silicon wafers in two consecutive steps: First the silicon wafer was coated with a propionaldehyde plasma polymer layer (AHPP); secondly, the PLL-g-PEG was immobilized covalently by reacting part of the amine groups of the PLL backbone with the aldehyde groups present on the plasma-deposited polymer layer (reductive amination). The stability and the protein resistance of different architectures of PLL-g-PEG were quantitatively investigated by XPS, OWLS and ToF-SIMS. Protein resistance of the polymer-modified surfaces was tested against bovine serum albumin (BSA). Adsorption of BSA was below the detection limit (below 2 ng/cm@super 2@), similarly to the electrostatically adsorbed PLL-g-PEG. However, after 24 h exposure of the covalently immobilized PLL-g-PEG to high ionic strength buffer (2400 mM NaCl) no significant change in the protein resistance was observed, while under the same conditions electrostatically adsorbed PLL-g-PEG coatings lost their protein resistant properties. These findings provide good evidence for the covalent nature of the PLL-g-PEG binding to the surface. This work has created a general platform for the covalent immobilization of PLL-g-PEG onto a wide variety of substrates provided that they are compatible with the AHPP coating process.