Synthesis of Gold Microplates Using Bovine Serum Albumin as a Reductant and a Stabilizer

Gold microplates were synthesized in aqueous solutions by reducing HAuCl4 with the hydroxyl groups in both serine and threonine of bovine serum albumin (BSA), which is a globular protein in its native state. In this article, we systematically investigated the effects of temperature, pH value, the concentration of BSA, and ionic species on the reduction kinetics and thus the size and morphology of the final product. The optimal experimental conditions for producing uniform Au microplates include the following: an elevated temperature in the range of 55–65 °C, an acidic solution with pH≈3, and the presence of NaCl (0.14 M). We found that if any one of these parameters was deviated from the optimal condition, Au microplates would not be formed in high yields. We also found that the surfaces of the as‐synthesized Au microplates were covered by a dense array of BSA bumps. A double agent exposed: Bovine serum albumin (BSA), a globular protein, was employed as both the reductant and stabilizer in the preparation of Au microplates with a narrow size distribution through a facile synthetic approach.The hydroxyl groups in BSA served as a weak reducing agent at mild temperatures, thus providing a kinetically controlled pathway to generate seeds with planar defects, which then grow into Au microplates.