(448x) Understanding Ligand–Nanoparticle Interactions for Silica, Ceria, and Titania Nanopowders

We perform a study on aqueous suspensions of three types of nanoparticles (TiO2-NPs, CeO2-NPs,SiO2-NPs) and investigate the material properties and the surface reaction with surfactant-type ligands to their subsequent colloidal stability, the key factors to their impact on the environmental health and safety (EHS). Bovine serum albumin, sodium dodecyl sulfate, and cetyltrimethylammonium bromide were used as representative surfactant ligands. Electrospray differential mobility analysis, dynamic light scattering, zeta potential measurement, transmission electron microscopy, inductively coupled plasma mass spectrometry, x-ray diffraction spectrometry were employed orthogonally to obtain particle size, morphology, surface corona, concentration and composition, and the change in colloidal stability. Results show that colloidal stability was strongly affected by the surface properties of nanoparticles and the subsequent interactions with ligands under different environmental conditions. Aggregation was shown to be the dominant process to colloidal instability. Our work demonstrates a prototype study to investigate the change of surface charges and the fate of nanomaterialâ??s colloidal stability after interacting with ligands and their subsequent impact in EHS.