Highly stable gold nanoparticles in an aqueous solution without any stabilizer prepared by a solution plasma process evaluated through capillary zone electrophoresis.

Gold nanoparticles (AuNP) were prepared by a solution plasma process in the presence of H 2 O 2 , and they were dispersed in an aqueous solution without any stabilizer generally used. The dispersion stability of the AuNP in an aqueous solution was evaluated by capillary zone electrophoresis (CZE). An anionic broad peak was detected with the AuNP by CZE based on its wide variations in size and net charge. The broad peak also suggests that the AuNP were well dispersed in an aqueous solution. The dispersion stability of AuNP was evaluated from the viewpoints of long-term dispersion, salt concentration, and organic co-solvent. The anionic broad peak attributed to the dispersed AuNP was successfully detected for at least 55 weeks from the preparation with less shot signals of the aggregates. The AuNP was also well dispersed in aqueous NaCl solutions with its concentrations up to 30 mmol L -1 , as well as with ethanol co-solvent up to 40%(v/v). The AuNP prepared by the solution plasma process was proved to be highly stable in an aqueous solution.