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A liquid crystal-based sensor for the simple and sensitive detection of cellulase and cysteine B Biointerfaces

Wang, Yi, Hu, Qiongzheng, Tian, Tongtong, Gao, Yan’an, Yu, Li
Colloids and surfaces 2016 v.147 pp. 100-105
colloids, copper, cysteine, detection limit, endo-1,4-beta-glucanase, enzymatic hydrolysis, enzyme activity, liquid crystals, monitoring, surfactants
A liquid crystal (LC)-based sensor, which is capable of monitoring enzymatic activity at the aqueous/LC interface and detecting cellulase and cysteine (Cys), was herein reported. When functionalized with a surfactant, dodecyl β-d-glucopyranoside, the 4-cyano-4′-pentylbiphenyl (5CB) displays a dark-to-bright transition in the optical appearance for cellulase. We attribute this change to the orientational transition of LCs, as a result of enzymatic hydrolysis between cellulase and surfactant. Furthermore, by adding cellulase and Cu²⁺, our surfactant-LCs system performs an interesting ability to detect Cys, even though Cys could not interact with surfactant or LC directly. Alternatively, through the strong binding between Cys and Cu²⁺, cellulase was able to hydrolyze surfactant in the presence of Cu²⁺, leading to the transition of LCs from dark to bright. The detection limit of the LC sensor was around 1×10⁻⁵mg/mL and 82.5μM for cellulase and Cys, respectively. The LC-based sensor may contribute to the development of low-cost, expedient, and label-free detection for cellulase and Cys and the design strategy may also provide a novel way for detecting multiple analytes.