Using liquid crystals to detect DNA hybridization on polymeric surfaces with continuous wavy features.

In this study, we examined the orientational behavior of thermotropic liquid crystals (LCs) supported on a film of DNA that was chemically immobilized on a nanostructure surface. The surface was comprised of gold film deposited onto a polymer substrate that had a sinusoidal distortion normal to the surface, leading to a parallel array of peaks and troughs. The sinusoidal structures were produced by treating a polydimethylsiloxane (PDMS) substrate with oxygen plasma and buckled on a cylindrical surface. This patterned PDMS was then used to create replicas of the associated relief structures on another polymer surface, poly(urethaneacrylate), where a film of gold was deposited. The gold films were functionalized with thiol-modified DNA, and then used as substrates for the hybridization of a complementary strand of DNA (cDNA). The orientation of nematic 4-cyano-4'-pentylbiphenyl (5CB) was found to be parallel to the plane of the surface-immobilized DNA before incubation with a solution of cDNA. However, the hybridization of DNA induced a random orientation of 5CB, indicating that the DNA complexes disturbed the sinusoidal structure of the surface. These results demonstrate that LC can be used to detect the hybridization of DNA by manipulating the response of LC to the DNA decorated surfaces.