TWO DISTINCT FLUORESCENT QUANTUM CLUSTERS OF GOLD STARTING FROM METALLIC NANOPARTICLES BY PH-DEPENDENT LIGAND ETCHING

Abstract

Two fluorescent quantum clusters of gold, namely Au25 and Au8, have been synthesized from mercaptosuccinic acid-protected gold nanoparticles of 4 5 nm core diameter by etching with excess glutathione. While etching at pH ~3 yielded Au25, that at pH 7 8 yielded Au8. This is the fi rst report of the synthesis of two quantum clusters starting from a single precursor. This simple method makes it possible to synthesize well-defined clusters in gram quantities. Since these clusters are highly fl uorescent and are highly biocompatible due to their low metallic content, they can be used for diagnostic applications.