Biological synthesis of platinum nanoparticles with apoferritin

A novel biological method for the synthesis of platinum nanoparticles using the horse spleen apoferritin (HSAF) is reported. When HSAF was incubated with K₂PtCl₆ at 23°C) for 48 h followed by subsequent reduction with NaBH₄ it resulted in the formation of spherical platinum nanoparticles, size 4.7 ± 0.9 nm, with narrow particle size distribution confirmed by transmission electron microscopy and energy dispersive X-ray analysis. As the initial platinum concentration increased through 0.155, 0.31, 0.465 to 0.62 mM the efficiency of its removal from solution by the apoferritin was 99, 99, 84 and 71% respectively. The maximum uptake of platinum salt per mM apoferritin was estimated at 12.7 mmol l⁻¹ h⁻¹. These results clearly indicate that the HSAF protein cage can successfully serve as a suitable size-constrained support matrix for the biological synthesis of platinum nanoparticles.