PLASMA DEPOSITION OF ULTRATHIN FILMS OF POLY(2-HYDROXYETHYL METHACRYLATE) - SURFACE-ANALYSIS AND PROTEIN ADSORPTION MEASUREMENTS

A method for the preparation of ultrathin films of poly(2-hydroxyethyl methacrylate) (PHEMA) by simultaneous condensation and RF plasma deposition of 2-hydroxyethyl methacrylate (HEMA) is described. Interactions of proteins with plasma-deposited and model PHEMA surfaces (spin-cast PHEMA, radiation-grafted PHEMA, and bulk PHEMA gels) were examined. Films prepared by conventional plasma deposition (i.e., without enhancing HEMA condensation by substrate temperature reduction) were also studied. I-125-radiolabeled fibrinogen was used to study the protein adsorption and retention characteristics of these materials. Kinetic protein adsorption and free iodide uptake studies were performed. In addition, gravimetric analysis, X-ray photoelectron spectroscopy, static secondary ion mass spectrometry, and water contact angle measurements were made to compare physical and chemical properties of the various hydrogel specimens and to gain insight into the reasons for their different protein interactions. Results demonstrate that plasma deposition of HEMA on substrates at low substrate temperatures is a viable method for preparing ultrathin, hydrogel films for biomedical applications.