Web Release Date: February 9,
pH-Dependent Aggregation of Histidine-Functionalized Au Nanoparticles Induced by Fe3+ Ions
Key Laboratory of Surface and Interface Chemistry of Jilin Province, College of Chemistry, Jilin University, Changchun 130012, P. R. China
Received: October 5, 2007
In Final Form: December 1, 2007
Abstract:
The aggregation of histidine-functionalized Au nanoparticles induced by Fe3+ was identified to show pH-dependent character. At low pH value, the Fe3+ ion was effective to induce aggregation of the Au nanoparticles
via its coordination with imidazole group of the histidine ligand. At pH value higher than 9, the histidine
ligand provided an additional coordination site for the Fe3+ ion due to deprotonization of its 
-NH2 group.
Therefore, the Fe3+ ion-induced aggregation of the Au nanoparticles was suppressed as a result of the
transformation of the histidine from monodentate to bidentate ligand upon increased pH value.
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