Gold nanoparticles (AuNPs) are among the most important metal nanoparticles with unique size-dependent
properties, and they have been applied in various fields including as catalysts, biomarkers, and in drug delivery.
Various methods have been utilized to synthesize AuNPs, but chemical methods are the most commonly
employed for preparing AuNPs from chloroauric acid (HAuCl4) as a precursor. Amine compounds are attractive
as reducing agents for use in the synthesis of AuNPs because it is possible to control the growth rate of AuNPs and
to tune their optical properties. Among the various amine compounds, dendrimers may be effective reducing
agents because of their peripheral primary amine groups. In this study, we used a 5th generation poly(propylene
imine) (PPI) dendrimer (G5A) with ethylenediamine (EDA) core as simultaneous reducing and stabilizing agent
to synthesize AuNPs produced from HAuCl4. Different amounts of aqueous G5A solution were added to the
aqueous gold salt solution and a reduction reaction was performed under mild conditions. The results showed
that reducing HAuCl4 with the dendrimer molecules yielded low stable colloidal nanoparticles because the
electrostatic repulsion between the AuNPs was affected by the neutral pH of the final medium. In addition, the
results confirmed that the dendrimer molecules were deposited on the surfaces of the AuNPs to stabilize the
colloidal nanoparticles.