Nitrilotriacetic acid: A novel reducing agent for synthesizing colloidal gold

• Stable gold sols were prepared by reducing [AuCl4]− with nitrilotriacetic acid (NTA).
• The concentration of reductant dictates the size of gold nanoparticles.
• A large NTA excess is necessary to prevent the aggregation of Au nanoparticles.
• Stable sols with a concentration up to 1.5 × 10−3 mol dm−3 have been prepared.

We report for the first time that nitrilotriacetic acid (NTA) is an effective reductant for the preparation of stable dispersions of uniform gold nanoparticles. The method described is capable of generating stable sols with a metal concentration as high as 1.5 × 10−3 mol dm−3. The size of gold nanoparticles can be tuned from 10 to 160 nm by adjusting the stoichiometric excess of NTA. For a constant [Au]/[NTA] ratio the temperature affects the reduction kinetics but has little impact on the size of gold nanoparticles. The mechanisms of the reduction of Au(III) species and the formation and stabilization of gold nanoparticles are discussed.

Figure optionsDownload high-quality image (150 K)Download as PowerPoint slide