BIOLOGICAL DETECTION USING FUNCTIONAL GOLD NANOCLUSTERS
Yonsei University, South Korea
Gold nanoclusters with atomic precision, for example, Au25(SR)18, Au38(SR)24, Au67(SR)35 and Au144(SR)60, where SR is organothiol, have attracted much attention in recent years because of their importance in both fundamental science and technological applications. These oleculelike nanoclusters display unique properties, such as quantized single-electron charging and molecule-like redox activities, that differ substantially from those of the corresponding atoms and bulk materials. This presentation reports electrochemical and optical properties of these nanoclusters and their use in electrochemical sensing. Voltammetry of these nanoclusters exhibited well-resolved, reversible redox peaks and size-dependent electrochemical HOMOLUMO gaps that could be correlated to optical and calculated energy gaps. These nanoclusters also showed excellent electrocatalytic activity toward oxidation of biologically relevant analytes. The modified electrode film prepared with Au25 nanoclusters exhibited excellent mediated electrocatalytic activity that was utilized for amperometric sensing of dopamine and glucose. The electron transfer dynamics in the Au25 film was examined as a function of Au25 concentration, which manifested the dual role of Au25 as an electronic conductor as well as a redox mediator. The electron transfer study has further revealed the correlation between the electronic conductivity of the Au25 film and the sensing sensitivity.