Facile Formation of Highly Mobile Supported Lipid Bilayers on Surface-Quaternized pH-Responsive Polymer Brushes

• DOI: 10.1021/acs.macromol.5b00435
• Publication Date: 2015-04-16T19:01:08Z
• Authors: N. Cheng; P. Bao; S. D. Evans; G. J. Leggett; S. P. Armes
• Keywords: Atom-transfer radical-polymerization; Polymer brush

Poly(2-dimethylamino)ethyl methacrylate) (PDMA) brushes are grown from planar substrates via surface atom transfer radical polymerization (ATRP). Quaternization of these is conducted using 1-iodooctadecane in n-hexane, which a non-solvent for PDMA. Ellipsometry, AFM, and water contact angle measurements show that surface-confined quaternization occurs under conditions, producing pH-responsive have hydrophobic upper surface. Systematic variation the concentration reaction time enables mean degree to be optimized. Relatively low degrees (ca. 10 mol % as judged by XPS) produce enable formation supported lipid bilayers, with pendent octadecyl groups promoting situ rupture vesicles. Control experiments confirm quaternized PDMA prepared good brush solvent (THF) non-pH-responsive brushes, presumably because form micelle-like physical cross-links throughout layer. Supported bilayers (SLBs) can also formed on non-quaternized precursor but such structures proved unstable small changes pH. Thus, n-hexane provides best protocol robust SLBs. Fluorescence recovery after photobleaching (FRAP) studies SLBs indicate diffusion coefficients (2.8 ± 0.3 μm s–1) mobile fractions (98 2%) comparable literature data reported directly glass substrates.