Spontaneous Formation of Functionalized Dendrimer-Stabilized Gold Nanoparticles

Functionalized, dendrimer-stabilized gold nanoparticles (Au DSNPs) are of scientific and technological interest for biological applications. In this work, we show that acetamide-functionalized Au DSNPs can be formed by acetylation of amine-terminated poly(amidoamine) (PAMAM) dendrimers of generation 5 (G5.NH(2)) complexed with Au(III) ions (AuCl(4) (-)). In addition, hydroxyl-functionalized Au DSNPs can be formed by simply mixing the glycidol hydroxyl-terminated G5 dendrimers (G5.NGlyOH) with HAuCl(4). In both cases, no additional reducing agents were needed and the reactions were completed at room temperature. We also show that Alexa Fluor 594 dye-functionalized Au DSNPs can be formed by acetylation of Alexa Fluor 594-conjugated, amine-terminated G5 dendrimers complexed with HAuCl(4). All of these functionalized Au DSNPs are water-soluble and stable. Fluorescence spectroscopy studies reveal that the Alexa Fluor 594-functionalized Au DSNPs retain similar fluorescence intensity to the Alexa Fluor 594-functionalized dendrimers that lack Au nanoparticles. These preparations of Au DSNPs provide a straightforward approach to synthesizing functionalized metal nanoparticles for biomedical applications.