Preparation of Stable Water-Dispersible PEGylated Gold Nanoparticles Assisted by Nonequilibrium Atmospheric-Pressure Plasma Jets

Water-dispersible gold nanoparticles with narrow size distributions were prepared by irradiation of nonequilibrium atmospheric-pressure dielectric-barrier-discharge (DBD) helium plasma jets to tetrachloroauric acid solutions containing poly(ethylene glycol) (PEG) that had a pentaethylenehexamine at one end of each polymer chain (N6-PEG). N6-PEG is known to interact with aurate cations to facilitate nucleation and growth of gold nanoparticles as a surface-modification agent. The helium-based DBD plasma jets contain energetic electrons and free radicals, which can induce chemical reactions on the surface of and/or in a solution at room temperature. For gold nanoparticles formed by DBD plasma-jet irradiation with the molar ratio of tetrachloroauric acid/N6-PEG being 1:20 at pH 10, the average particle size was in the range of 5-10 nm in diameter from transmission electron microscopy observation. Furthermore, gold nanoparticles prepared in this manner are found to have remarkable stability under physiological conditions because of the immobilization of PEG-derived materials on the gold Surfaces. Such gold nanoparticles may therefore be considered excellent candidates for high-performance bionanoparticles.