Synthesis of Dendrimer-Passivated Noble Metal Nanoparticles in a Polar Medium: Comparison of Size between Silver and Gold Particles

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• 作者：Abhijit Manna ; Toyoko Imae ; Keigo Aoi ; Masahiko Okada ; and Toshinobu Yogo
• 刊名：Chemistry of Materials
• 出版年：2001
• 出版时间：May 2001
• 年：2001
• 卷：13
• 期：5
• 页码：1674 - 1681
• 全文大小：257K
• 年卷期：v.13,no.5(May 2001)
• ISSN：1520-5002

文摘

The synthesis of silver and gold metal nanospherical particles stabilized by the fourth-generation poly(amido amine) (G4 PAMAM) dendrimer is reported. The reduction of silvernitrate and sodium tetrachloroaurate in the presence of the PAMAM dendrimer havingterminal amine groups results in the formation of stable, water-soluble nanoparticles. Theformation and size of the particles have been determined from the UV-vis plasmonabsorption band and transmission electron microscopic (TEM) analyses. The average particlesizes are (6.2 ± 1.7)-(12.2 ± 2.9) nm for silver and are (3.2 ± 0.7)-(7.3 ± 1.5) nm for gold,depending on the metal ion-to-dendrimer terminal amine ratio (M:D) used. Thus, dendrimer-protected silver particles are substantially larger than the gold particles synthesized insimilar systems. Nanoparticles prepared at 0.25:1 and lower M:D ratios are stable for along period of time. A TEM study of the morphology also shows a short-ranged hexagonalarrangement of particles in a monolayer onto the carbon-coated copper TEM grid. Detailedparticle size analysis studies by TEM support the possibility that the terminal amino groupsof the dendrimers take part in the stabilization of the nanoparticles. The evidence fromX-ray photoelectron spectroscopic and Fourier transform infrared absorption spectroscopicinvestigations confirms the valence state of the gold and the encapsulation by the dendrimer.