Preparation of Homogeneous Gold−Silver Alloy Nanoparticles Using the Apoferritin Cavity As a Nanoreactor

Homogeneous Au−Ag alloy nanoparticles have been synthesized in the cavity of horse spleen apoferritin (HSAF) by a diffusion technique. The Au−Ag nanoparticle cores are 5.6−6.3 nm in diameter with narrow size distribution (≤1.0 nm), and their average diameter was gradually increased with an increase in the Ag content. The core formation ratios of Au−Ag−HASF samples are higher than 80%. These series of nanoparticles were applied for the reduction of 4-nitrophenol in the presence of NaBH 4 . As the Au content was increased in the Au−Ag−HSAF nanoparticles, the rate constant of the reduction was exponentially increased from 1.3 × 10 −3 s −1 (pure Ag−HSAF) to 7.58 × 10 −2 s −1 (pure Au−HSAF). These synthesized Au−Ag nanoparticles with different compositions will be further applicable in catalysis, sensing, and biomedical areas.