Polydopamine as an Efficient Polymer to Prepare Biologically Relevant Supported Lipid Bilayers

Abstract

Solid-supported lipid bilayers (s-SLBs) are widely used as versatile biological membrane mimics. However, lipid-solid surface interactions and ensuing frictions lead to a decrease in lipid mobility. To address this issue, we prepared polymer-supported lipid membranes using a soft polymer cushion as a lubricating layer. A bioinspired polymer, polydopamine was chosen due to its ability to easily form thin coatings onto a wide range of surfaces, with a control of the thickness depending on the immersion time of the substrate.Polydopamine coated-mica was used to support zwitterionic phospholipid bilayers of dimyristoylphosphatidylcholine (DMPC) or dioleoylphosphatidylcholine (DOPC). Atomic Force Microscopy (AFM) was performed to verify the deposition of DMPC and DOPC bilayers, revealing the presence of lipid patches on the polymer surface. The addition of positively charged cholesterol (DC-Chol) in the membrane composition greatly improved the lipid surface coverage (up to 90%). Best results were obtained for 20 and 30% DC-Chol containing membranes.They were also further characterized with other surface-sensitive techniques such as fluorescence microscopy to assess the phospholipid mobility. Surface Plasmon Resonance (SPR) and Quartz Crystal Microbalance with Dissipation (QCM-D) results showed the irreversible deposition of the lipid bilayers on the polymer surface. The polydopamine polymer film proved to be efficient to maintain fluidity of the phospholipid bilayers, thus enhancing this class of membrane model. We will present practical application of our s-SLBs onto porous filters as an improved model of Parallel Artificial Membrane Permeability Assay (PAMPA) to better predict passive permeation of orally administered drugs.