Size-selective separation of gold nanoparticles using isoelectric focusing electrophoresis (IEF).

Isoelectric focusing in a polyacrylamide pH gradient gel is used to analyze the size distribution of gold nanoparticles synthesized by a chemical route with mercaptosuccinic acid as a ligand. The isoelectric point of the nanoparticles is shown to be size dependent, allowing fractionation by electrophoresis. Each fraction has a narrow size distribution with a standard deviation lower than 0.4 nm.