Strategies for radiolabeling of commercial TiO₂ nanopowder as a tool for sensitive nanoparticle detection in complex matrices

Detection and quantification of engineered nanoparticles (NPs) in complex environmental or biological media is a major challenge since NP concentrations are generally expected to be low compared to elemental background levels. This study presents three different options for radiolabeling of commercial titania NP (TiO₂-NP, AEROXIDE^® P25, Evonik Industries, mean diameter 21 nm) for particle detection, localization, and tracing under various experimental conditions. The radiolabeling procedures ensure stability and consistency of important particle properties such as size and morphology. With the presented radiolabeling methods, detection (and quantification) limits for TiO₂-NPs in concentrations as low as 0.5 ng/L can be realized in complex systems without the necessity of intense sample purification or pretreatment