Radiolabelling of nanoparticles and its use for transport studies

Hundreds of products containing nanoparticles (NP) are already in use. Nanotechnological innovation is identified in many sectors, including public health, employment and occupational health and safety, information society, industry, environmental protection, fuel and energy generation, transportation, security and space exploration. But the new materials may also pose risks to the environment and raise health and safety concerns. These risks have been addressed in several ongoing research projects. The overall conclusion so far is that, even though NP are not per se dangerous, there still is scientific uncertainty about the safety of NP in many aspects and therefore the safety assessment of the substances must be done on a case-by-case basis.
A key factor for the fate of NP in the environment and their introduction into the food chain is the bioavailability and thereby the mobility of the NP. Multiple factors control the migration behaviour of the NP in water and water saturated/unsaturated soils. Reversible and irreversible physical and chemical interactions cause a complex scenario with a great variety of boundary conditions. The transport of NP through soil, water and sediments is influenced by advection, diffusion, retardation due to sedimentation, filtration, staining, size exclusion effects, aging due to chemical corrosion, sorption and aggregation.
The experimental access to transport studies requires the observation of NP in complex environmental media at naturally relevant concentrations. This is a major challenge in laboratory work which can be overcome by the use of radiotracers.
In this work we present different techniques for the introduction of the radiotracers into the NP (Ag0, TiO2, MWCNT) including activation of NP, radiosynthesis of NP, radiolabelling of NP, self-diffusion of radioisotopes into NP and recoil labeling. The radiolabelled NP were used for 1D and 4D (time resolved Positron Emission Tomography (PET)) transport studies. The first results of the transport studies (BTC- break through curves and PET images) will be given as prove of principle.