Liquid crystal-based aptamer sensor for sensitive detection of bisphenol A

Bisphenol A (BPA) is an environmental poison that seriously affects the health of humans. Herein, a novel, label-free, time-saving liquid crystal-based aptamer sensor for the detection of BPA was developed based on the specific binding of an aptamer and its target. In this study, the surface of the sensor was assembled with (3-aminopropyl)triethoxysilane & dimethyloctadecyl[3-(trimethoxysilyl) propyl]ammonium chloride and the amino-aptamer was attached to this film via glutaradehyde links. Through a specific reaction, BPA reacts with the BPA aptamer forming an 'aptamer-BPA' complex that changes the conformation of the BPA aptamer. Through spatial size effects, the large size of the complex disturbs the nematic orientation of 4-cyano-4'-pentybiphenyl in the film on this surface from homeotropic to random, resulting in an image that changes from 'dark' to 'bright' under a polarized light microscope. The limit of detection of this system is 600 pM. Atomic force microscopy was also employed to further validate the results.