AVS 51st International Symposium
    Biomaterial Interfaces Monday Sessions
       Session BI-MoP

Paper BI-MoP34
Immobilization of the Enamel Matrix Derivate Protein Emdogain onto Polypeptide Multilayers as studied by in situ Ellipsometry and QCM-D

Monday, November 15, 2004, 5:00 pm, Room Exhibit Hall B

Session: Poster Session
Presenter: T.J. Halthur, Royal Institute of Technology, Sweden
Authors: T.J. Halthur, Royal Institute of Technology, Sweden
I. Slaby, Biora AB, Sweden
A. Lindeheim, Biora AB, Sweden
P. Claesson, Royal Institute of Technology, Sweden
U. Elofsson, YKI AB, Institute for Surface Chemistry, Sweden
Correspondent: Click to Email
The build-up of the biodegradable poly(L-glutamic acid) (PGA) and poly(L-lysine) (PLL) multilayers on silica and titanium surfaces, with and without an initial layer of polyethyleneimine (PEI), was investigated and characterized by means of in situ ellipsometry and Quartz Crystal Microbalance with Dissipation (QCM-D). A two-regime build-up was found in all systems, where the length of the first slow growing regime is dependent on the structure of the initial layers. In the second fast growing regime, the film thickness grows linearly while the mass increases more than linearly (close to exponentially) with the number of deposited layers. The film refractive indices as well as the water contents, indicate that the film density changes as the multilayer film builds up. The change in film density was proposed to be due to polypeptides diffusing into the multilayer film as they attach. Furthermore, the use of PEI as initial layer was found to induce a difference in the thickness increments for PGA and PLL. Comparisons between ellipsometry and QCM measurements revealed that the multilayer film was highly hydrated (as much as 70-75% water) and might therefore serve as a good template for proteins and cells. The hydrophobic aggregating Enamel Matrix Derivatives (EMD) protein Emdogain was successfully immobilized both on top of as well as within the multilayer structures while measured in situ with ellipsometry and QCM and in vitro with ELISA. These polypeptidemultilayer/EMD films are thought to be able to trigger cell response and induce biomineralization and might therefore be used as bioactive and biodegradable coatings for future dental implants.