Dispersibility improvement of gold/iron-oxide composite nanoparticles by polyethylenimine modification

Composite gold/iron-oxide nanoparticles were synthesized by a sonochemical process and their surface then modified with polyethylenimine (PEI). The dispersibility of the composite nanoparticles in acidic solution was improved by the PEI modification. The composite nanoparticles specifically adsorbed sulfur-containing amino acids and could be picked up by an external magnetic field. Thus, composite nanoparticles modified with PEI carry both the ability to bond Au–S and to disperse well in buffer solutions.