Gold Nanoparticles and Hydrophobic Ionic Liquid Applied on the Development of a Voltammetric Biosensor for Polyphenol Determination

A novel biosensor based on gold nanoparticles dispersed in ionic liquid 1-butyl-3-methylimidazolium hexafluorophosphate (Au-BMI.PF(6)) and polyphenol oxidase (PPO) from garlic (Allium sativum L.) immobilized in clay was developed for determination of polyphenol by square-wave voltammetry. Under optimized conditions, the analytical curve showed a linear range for esculetin concentrations from 0.40 to 9.86 mu M (R=0.9997), with a limit of detection (LOD) of 0.11 mu M. This biosensor demonstrated good repeatability and reproducibility, with relative standard deviations of 3.5% and 4.6%, respectively. The method was successfully applied to the determination of esculetin content in black tea samples.