Bienzyme liquid-crystal-based cholesterol biosensor

A cholesterol biosensor was fabricated by coating 4-cyano-4′-pentylbiphenyl (5CB) in a transmission electron microscope (TEM) grid with poly(acrylicacid-b-4-cyno-4′-undecyl acrylate) (PAA-b-LCP), followed by co-immobilization of cholesterol oxidase and horseradish peroxidase on the PAA brushes. This TEM grid sensor was tested for stability and sensitivity of the immobilized enzymes to cholesterol. Cholesterol was detected by a planar-to-homeotropic orientational change of 5CB at a limit of 0.8 mM. The high stability, ease of preparation, and specific detection of cholesterol in a complex mixture, could provide a new and convenient method for screening cholesterol levels in a sample using a polarized optical microscope.