Chemical functionalization and modification of surface-bound cystamine–glycine monolayers on gold nanoparticles

Herein, we report the synthesis, characterization, and post-functionalization of Au nanoparticles that have been surface-modified with glycine–cystamine (Gly-CSA) stabilizing groups. We show that Au monolayer protected clusters (MPCs) can be synthesized via the Brust–Schiffrin method using a Boc-Gly–CSA stabilizer, followed by efficient removal of the Boc protecting group with trifluoroacetic acid. The resulting Gly–CSA Au MPCs are characterized via UV–vis, TEM, and 1 H NMR, and are stable in solution over long periods of time. Finally, we show that the Gly–CSA Au MPCs can be further functionalized with nearly stoichiometric yields using activated esters of stearic acid and a Bodipy dye derivative. Thus, this work provides an alternative, general approach for the modification of the surface chemistry of MPCs.Key words: gold nanoparticles, peptide stabilizers, dyes.