Measuring ligand-receptor binding events on polymeric surfaces with periodic wave patterns using liquid crystals

Abstract

In this study, we measured ligand-receptor binding events on polymeric substrates with periodic nanostructures using liquid crystals (LCs). Periodic sinusoidal wave patterns were generated through the buckling of the poly-(dimethylsiloxane) (PDMS) substrate on a cylindrical surface followed by replicating the associated relief structures on a poly-(urethane acrylate) (PUA) surface, where a film of gold was deposited. Avidin was then covalently immobilized onto a gold surface decorated with carboxylic acid-terminated self-assembled monolayer via NHS/EDC chemistry. The optical response of the device showed that the orientation of nematic 4-cyano-4'-pentylbiphenyl (5CB) was parallel to the plane of the avidin surface. However, the formation of the avidin-biotin complexes disturbed the sinusoidal topographies of the surface, and induced a random orientation of LCs, which produced a distinctive change in the optical response. We also confirmed the specific ligand-receptor interactions using ellipsometry and atomic force microscopy (AFM). These results suggest that polymeric surfaces with continuous wavy features could be used to develop novel LC-based sensors for the detection of ligand-receptor binding events. (C) 2012 Elsevier B.V. All rights reserved.