Fast and Cost‐Effective Purification of Gold Nanoparticles in the 20–250 nm Size Range by Continuous Density Gradient Centrifugation

A multilayer quasi-continuous density gradient centrifugation method for separating 20-250 nm metal colloids with high size resolution while maintaining particle stability is presented. Colloidal mixtures containing monodisperse gold nanospheres and clusters thereof, in particular, gold dimers, are purified with yields up to 94%. The rapid method uses standard laboratory equipment.