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pH-Dependent Aggregation of Histidine-Functionalized Au Nanoparticles Induced by Fe3+ Ions

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journal contribution
posted on 06.03.2008, 00:00 by Jian Guan, Lin Jiang, Jun Li, Wensheng Yang
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 α-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.