Reversible Activation of Diblock Copolymer Monolayers at the Interface by pH Modulation, 2:  Membrane Interactions at the Solid/Liquid Interface

Abstract

A monolayer of the pH-responsive poly[2-(dimethylamino)ethyl methacrylate-block-methyl methacrylate] diblock copolymer [PDMAEMA-PMMA] was transferred from the air/water interface to a silicon substrate for evaluation as a tunable interlayer between biological material and solid substrates. Specular neutron reflectivity experiments revealed that the weak polyelectrolyte PDMAEMA chains at the solid/liquid interface can be reversibly activated by pH modulation. The thickness, scattering length density, and surface roughness of the polymer film can be systematically controlled by pH titration. As a simple model of plasma membranes, a lipid bilayer was deposited onto the polymer film. The membrane-substrate interaction was characterized by neutron reflectivity experiments, demonstrating that the membrane-substrate distance could be reversibly regulated by pH titration. These results confirm the potential of stimuli-responsive polymers for precise control of cell-surface interactions.

Neutron reflectometry from poly (ethylene-glycol) brushes binding anti-PEG antibodies: Evidence of ternary adsorption

“…Combining the contributions of the lipid tails and headgroups into a single slab of thickness d lip is an approximation commonly used in NR to reduce the number of adjustable parameters in the model [49,50]. The SLD of silicon oxide was fixed at the literature value, r SiO2 ¼ 3.4 Â 10 À6 Å À2 .…”

Generic Role of Polymer Supports in the Fine Adjustment of Interfacial Interactions between Solid Substrates and Model Cell Membranes

“…5 nm. However, in spite of numerous studies utilizing different polymers, including chemically immobilized or cross-linked hydrogels, 18,19 polymer brushes, 20,21 covalently grafted lipopolymers, 22, 23, 4 24 and polyelectrolyte multilayers, 25,26 there is no quantitative study that highlights how polymer supports would modulate the interfacial interactions.…”

Charging and structure of zwitterionic supported bilayer lipid membranes studied by streaming current measurements, fluorescence microscopy, and attenuated total reflection Fourier transform infrared spectroscopy

“…[7][8][9] The majority of studies on sBLMs were done on solid supports, such as mica, 10 glass, 11 or titanium dioxide. 12 Methods which have been applied for the characterization of sBLMs include combinations of atomic force microscopy and fluorescence correlation microscopy, 13 impedance measurements, 14 x-ray reflectivity, 15,16 and quartz crystal microbalance. 17 Since bilayer lipid membranes are prepared and applied in aqueous environments detailed knowledge about the role of electrostatic interactions in the formation of sBLM and the ionization characteristics of membranes formed from different types of lipids is required.…”