Aptamer based bare eye detection of kanamycin by using a liquid crystal film on a glass support

The authors describe an aptamer-based liquid crystal (LC) assay for kanamycin (KNM) that displays visible signal changes. The KNM aptamer was immobilized, along with the N, N-dimethyl-N-(3-(trimethoxysilyl) propyl)-1-octadecanaminiuchloride (DMOAP) on a glass slide, and this results in a homeotropic orientation of the LCs film. In the presence of KNM, its interaction with the aptamers will result in the formation of G-quadruplexes. These will destroy the orientated arrangement of the LCs on the surface to result in a color change from pink to green that can be visually observed by using crossed polarizers. The method possesses high specificity and the detection limit is as low as 1 nM. Unlike current laboratory-based KNM assays, this method does not require instrumental read-out which is highly beneficial in terms of on-site food analysis.