Synthesis and surface modification of highly fluorescent gold nanoclusters and their exploitation for cellular labeling

Abstract

ABSTRACT We introduce a general approach to make colorful fluorescent gold nanoclusters which are protected by dihydrolipoic acid, mercaptoundecanoic acid and polyethylenimine. The fluorescent gold nanoclusters can perform a variety of bioconjugation processes such as PEGylation, biotinylation as well as forming complex nanobioconjugates with streptavidins. The brightening effects under proper surface modification are also reported. The clusters have a decent quantum yield, high colloidal stability, and can be readily conjugated with biological molecules. Nonspecific uptake by human aortic endoth elial cells is demonstrated. Keywords: fluorescent gold nanoclusters, bioconjugation, near infrared, cell labeling, PEGylation, biotinylation, lipoic acid 1. INTRODUCTION Gold nanoclusters with size smaller than 2 nm have been gained great attention in the last decade for their unique role in bridging the link between atomic and nanoparticle behavior 1 . Researches have focused on their quantum physical properties including photoluminescence