Stable Protein-Repellent Zwitterionic Polymer Brushes Grafted from Silicon Nitride

• DOI: 10.1021/la104657c
• Publication Date: 2011-02-03T17:31:49Z
• Authors: Ai T. Nguyen; Jacob Baggerman; Jos M. J. Paulusse; Cees J. M. van Rijn; Han Zuilhof
• Keywords: density; Molecular Structure; Protein Stability; Surface Properties; poly(ethylene oxide) brushes; transfer radical polymerization; Silicon Compounds; self-assembled monolayers; Acrylic Resins; Proteins; 02 engineering and technology; organic monolayers; IR-99606; molecular simulation; Betaine; adhesion; adsorption; biosensor applications; Adsorption; 0210 nano-technology; surface modification

Zwitterionic poly(sulfobetaine acrylamide) (SBMAA) brushes were grafted from silicon-rich silicon nitride (SixN4, x > 3) surfaces by atom transfer radical polymerization (ATRP) and studied in protein adsorption experiments. To this aim ATRP initiators immobilized onto SixN4 through stable Si−C linkages via three consecutive reactions. A UV-induced reaction of 1,2-epoxy-9-decene with hydrogen-terminated was followed conversion the epoxide 1,2-ethylenediamine resulting primary secondary amine-terminated surfaces. 2-bromoisobutyryl bromide led to initiator-covered polymer SBMAA grown these initiator-coated (thickness ∼30 nm), polymer-coated characterized detail static water contact angle measurements, X-ray photoelectron spectroscopy (XPS), an atomic force microscope (AFM). The proteins zwitterionic coated evaluated situ reflectometry, using a fibrinogen (FIB) solution 0.1 g·L−1, compared hexadecyl-coated (C16−SixN4), uncoated air-based plasma oxidized (SiOy−SixN4), hexa(ethylene oxide)-coated (EO6−SixN4). Excellent repellence (>99%) observed for during exposure FIB as C16−SixN4 Furthermore, stability surveyed exposing 1 week phosphate buffered saline (PBS) at room temperature. before after PBS XPS, AFM, their protein-repelling properties reflectometry. After solution, coating remained intact, its thickness unchanged within experimental error. No hydrolysis still repelled 98% surfaces, demonstrating long-term efficiency easily prepared surface coatings.