Size Determination of Gold Clusters by Polyacrylamide Gel Electrophoresis in a Large Cluster Region

Polyacrylamide gel electrophoresis (PAGE) is used to separate the component of the glutathione protected gold clusters up to Au160 core size and compare the size with the mobility data from PAGE. Both electrospray mass spectrometry and transmission electron microscopy were systematically applied to analyze Au−glutathione clusters thus isolated. We have found a linear relationship between the mobility of the gold cluster compounds to the logarithm of the number of gold atoms of the core. Better fitting to the logarithm of the number of thiolate molecules adsorbed on the gold core was found and was expressed by a simple equation that bears conformation of ligand and charge density of clusters. Hence the mobility of the metallic clusters was correlated to the component of the ligand of the cluster.