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 endothelial cells is demonstrated.