One-step seed-mediated growth of 30-150 nm quasispherical gold nanoparticles with 2-mercaptosuccinic acid as a new reducing agent

We report herein a modified approach to the seed-mediated synthesis of large-diameter quasispherical gold nanoparticles by using 2-mercaptosuccinic acid (MSA) as a reducing agent in aqueous solution at room temperature. Simply through a one-step seeding growth approach, gold nanoparticles in the size range 30-150 nm were prepared from 15 nm gold seeds under the particular [HAuCl4]:[MSA] ratio of 1:0.6. Particle diameters could be controlled by varying the ratio of [HAuCl4]:[ seeds]. The resultant gold nanoparticles are quasispherical with narrow size distributions (relative standard deviation, RSD < 10%) and high yields; other nanostructures (nanorods, triangles, or hexagonal nanoplates) are rarely found, although they are frequently observed during the seeding growth when using hydroxylamine or ascorbic acid as reducing agents. The presence of MSA, which is not only a reducing agent but also a capping agent, is believed to make a great contribution to the isotropic growth of gold seeds and the formation of such monodisperse quasispherical particles.