Determination of the Relative Antioxidant Strength of Teas Combining Metal Nanoparticles, Plasmonics, and Fluorescence: A Multidisciplinary Experiment

Herein we present a multidisciplinary educational nanoscience experiment for a college undergraduate chemistry or nanoscience laboratory. This guided investigation has been designed to demonstrate to students, in a practical fashion and applying the scientific method, the fundamentals of redox reactions, synthesis of metal nanoparticles and applications of plasmonics, energy transfer, excitation processes, and fluorescence emission and quenching of dyes. The proposed activity gives students the opportunity to investigate, in a comparative mode, the antioxidant properties of teas. The relative antioxidant strength of three different types of tea (green, oolong and black tea) and one commercially available tea (Lipton black) is determined by monitoring the fluorescence quenching effect on a rhodamine 6G aqueous solution that contains silver nitrate. Through this experiment students can establish that green tea (the least oxidized in manufacturing) is the strongest antioxidant compared to oolong and black tea. Post-lab quizzes and survey show student learning and positive perception of the experiment. It is anticipated that this simple and interesting educational experiment could help to increase scientific literacy in multiple disciplines.