The development of a cholesterol biosensor using a liquid crystal/aqueous interface in a SDS-included β-cyclodextrin aqueous solution

Sodium dodecyl sulphate (SDS) including beta-cyclodextrin (beta-CD) (beta-CDSDS) was used to detect cholesterol at the 4-cyano-4'-pentylbiphenyl (5CB)/aqueous interface in transmission electron microscopy (TEM) grid cells. The beta-CD acts as a host for SDS (guest). The guest SDS enclosed within the beta-CD cavity was replaced with cholesterol by injecting cholesterol solution into the TEM cell at concentrations greater than 3 mu M. The replacement of SDS with cholesterol was confirmed by pH measurement and high performance liquid chromatography (HPLC). The SDS excluded from the beta-CD altered the planar orientation of the 5CB confined within the TEM grid cell to a homeotropic orientation. This planar-to-homeotropic transition was observed using a polarized optical microscope under crossed polarizers. This convenient TEM grid cell provides a new method for the selective detection of cholesterol without immobilization of the detecting receptors (enzyme, antibody, or aptamer) or the use of sophisticated instruments. (C) 2015 Elsevier B. V. All rights reserved.