Pacific Rim Symposium on Surfaces, Coatings and Interfaces (PacSurf 2016)
    Biomaterial Surfaces & Interfaces Thursday Sessions
       Session BI-ThM

Paper BI-ThM10
Quasi-zwitterionic Glow-Discharge Radio Frequency Plasma Coatings Reduce IgG Protein Adsorption

Thursday, December 15, 2016, 11:00 am, Room Milo

Session: Plasma for Biomedical Applications
Presenter: Marvin Mecwan, University of Washington, USA
Authors: M. Mecwan, University of Washington, USA
B.D. Ratner, University of Washington, USA
Correspondent: Click to Email
Introduction: Glow discharge plasma-treated surfaces have been used to create non-fouling surfaces, and can be readily applied to implants. For successful plasma polymerization it is important that the monomer of interest be easily volatilized. Zwitterionic polymer hydrogels in mice have shown to resist foreign-body reaction. However, zwitterionic polymer precursors, such as carboxybetaine methacrylate (CBMA) and sulfobetaine methacrylate (SBMA) are solids with high boiling points which would not make them ideal candidates for glow-discharge plasma treatment to coat surfaces. This study investigates the preparation of quasi-zwitterionic surfaces via glow-discharge plasma treatment prepared by the simultaneous deposition of a positively charged (allylamine or AAm), and negatively charged (acrylic acid or AAc) monomer, and its ability to act as a non-fouling surface.

Methods: Glass substrates were cleaned with MeOH in a sonication bath for 10 mins x 2. Substrates were loaded into the reactor, Ar etched (40W for 10 min), followed by a CH4 layer (80W for 5 min). The monomer of choice—AAc and AAm—was introduced into the chamber either by itself or simultaneously and plasma deposition was carried out at 150mT pressure; 80W for 1 min (adhesion) followed by 10W for 10 mins (deposition). Samples were quenched for 5 mins before venting the chamber and retrieving coated samples resulting in 3 treatment groups: AAc, AAm and AAc-AAm. Plasma-treated samples were washed using DI water x 3 and ESCA was used to assess coating composition before and after washing. ESCA analyses were done using an S-Probe ESCA (with monochromatic Al K-alpha X-rays focused to 800µm spot size) using survey and detailed C1s scans. Protein adsorption studies were performed using bovine IgG, and the amount of IgG adsorbed was determined by substrate based ELISA. Cytotoxicity studies were performed using NIH3T3 mouse fibroblast cells.

Results: ESCA scans of plasma-treated substrates showed absence of substrate associated peaks implying that plasma coatings on substrates are at least 10 nm thick (coating thickness will be measured using AFM). Furthermore, experimental and theoretical elemental compositions of the surfaces align well. Moreover, AAc-AAm coatings were able to reduce protein adsorption by 50% compared to untreated controls, and were non-cytotoxic.

Conclusions: The preliminary data demonstrates that quasi-zwitterionic surfaces can be successfully created, reduce IgG protein adsorption and are non-cytotoxic. Further optimization is required to reduce protein adsorption further in order to create a new generation of materials that perform efficaciously as non-fouling surfaces.