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

Colloids Surf B Biointerfaces. 2016 Nov 1:147:100-105. doi: 10.1016/j.colsurfb.2016.07.059. Epub 2016 Jul 29.

Abstract

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 Cu(2+), 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 Cu(2+), cellulase was able to hydrolyze surfactant in the presence of Cu(2+), leading to the transition of LCs from dark to bright. The detection limit of the LC sensor was around 1×10(-5)mg/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.

Keywords: Cellulase; Cysteine; Liquid crystals; Sensor.

MeSH terms

  • Biosensing Techniques / methods*
  • Cellulase / analysis*
  • Cellulase / metabolism
  • Cysteine / analysis*
  • Cysteine / metabolism
  • Humans
  • Hydrolysis
  • Limit of Detection
  • Liquid Crystals / chemistry*
  • Surface-Active Agents / chemistry*
  • Water / chemistry

Substances

  • Surface-Active Agents
  • Water
  • Cellulase
  • Cysteine