Colorimetric Detection of Perfluorooctanoic Acid (PFOA) Utilizing Polystyrene-Modified Gold Nanoparticles

Gold nanoparticles modified with thiol-terminated polystyrene (AuPS) were synthesized and applied to the colorimetric detection of perfluorooctanoic acid (PFOA). The color change of the AuPS solution from red to blue-purple upon addition of PFOA was easily confirmed by the naked eye. Using several acids and fluorinated compounds, the detection system was shown to be selective for PFOA and tridecafluoroheptanoic acid, which suggests that both a highly acidic carboxyl group and a fluorocarbon group are required for the color change. Transmission electron microscopy (TEM) suggested that the addition of PFOA caused detachment of the polystyrene layer from the surface of the gold nanoparticles, which resulted in interparticle aggregation.