AVS 47th International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI-WeP

Paper BI-WeP19
Study of Protein Adsorption on Hydrophilic and Hydrophobic Polysiloxane Surfaces Modified by O@sub 2@ Plasma Technique

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: C. Satriano, University of Catania, Italy
Authors: C. Satriano, University of Catania, Italy
F. Höök, Chalmers University of Technology and Göteborg University, Sweden
G. Marletta, University of Catania, Italy
B. Kasemo, Chalmers University of Technology, Sweden
Correspondent: Click to Email
Thin films of a poly(hydroxymethyl)siloxane have been chemically modified by using the O@sub 2@ plasma technique at increasing treatment times ranging from 15 seconds to 10 minutes, with the applied power of 100 Watts and a residual gas pressure of 0.25 torr. The plasma-induced surface chemical modifications were investigated in situ by means of X-Ray Photoelectron Spectroscopy (XPS) for both the in situ samples and the samples aged in air and/or in water. By means of Static Contact Angle measurements the wettability properties of the unmodified and the O@sub 2@ plasma-exposed surfaces were investigated. The XPS results show that the compositional modification involves a dramatic decrease in the carbon content and the formation of [SiO@sub 4@] clusters, indicating a successive transition with treatment time from the original [SiO@sub 3@C] structure to [SiO@sub x@C@sub y@] phases. The contact angle measurements indicate that the plasma treatment changes the initial hydrophobic surface (@theta@ ~ 90°) of the polymer into a completely wettable surface, with @theta@ = 0-10° contact angle. After aging in water the surface is still completely wettable, while aging in ambient atmosphere produces a mild recovery in the contact angle values. These surfaces are currently subject to measurements of protein adsorption and of vesicle to supported membrane transformations, using QCM-D and other techniques. The results of these measurements and how they correlate with the XPS and wetting angle measurements will be presented.