Protein detection using aqueous/LC interfaces decorated with a novel polyacrylic acid block liquid crystalline polymer

The interface between 5CB and water in a TEM grid by decoration of an amphiphilic block copolymer of PAA-b-LCP was examined for protein detection. Several proteins were detected at a few μM levels through homeotropic to planar orientational change (H-P change) of the 5CB. The H-P change became slow as the pH of water increased above the isoelectric point (pI) of the protein, and areal density of the monolayer and salt concentration increased. The TEM grid cell could detect proteins of human urine from a patient having albuminuria with a detection limit of as low as 0.032 mg mL^-1.