Sensitive and selective method for detecting cysteine based on optical properties of liquid crystal

Abstract

We demonstrate a novel strategy to detect cysteine using a liquid crystal (LC) biosensor at an aqueous interface. We synthesized a novel biosurfactant, which was effectively exploited to design an optical biosensor based on treated LC. Lauroyl-doped 5CB was used as a cysteine indicator based on the reaction between lauroyl chloride and cysteine at the aqueous/LC interface. Following the reaction, the orientation of LCs succeeded in a four-petal shape, as observed using a polarizing optical microscope where the optical signals received (as derived from the LCs orientation changes) were attributed to the newly formed biosurfactant. Additionally, the prepared biosensor has a LOD (limit of detection) of cysteine at the picomolar level (pM), better than that LOD which can be achieved by conventional methods These results suggest that use of a LC biosensor is an appropriate approach for cysteine detection, particularly for sensing low levels of cysteine in biological environments. (C) 2018 Elsevier B.V. All rights reserved.