Metal oxide and metal NPs are particularly dangerous for two reasons: their special catalytic activity coming from the properties of their nanointerface may interfere with numerous intracellular biochemical processes and the decomposition of NPs and the ion leakage could heavily interfere with the intracellular free metal ion homeostasis, which is essential for cell metabolism. A very specific problem is the difficulty of localizing and quantifying them in cells. Obtaining dose effect relationships is not simple, because of the unknown amount of material present in affected cells. The following main points will be addressed in this proposal:1) Design and synthesis of metal oxide and metal NPs, which can be traced by SPECT, PET, and fluorescence techniques and the appropriate characterization of these NPs.2) Application of label-free techniques, such as IBM and EM to ensure that the radioactive and fluorescent constituents do not modify the cytological and organismic response by themselves.3) Characterization of the uptake, distribution kinetics and NP release at the level of the organism.4) Study of the interaction of NPs with plasma components forming complexes with NPs and the assessment of their possible impact on the uptake compared with that of bare or capped particles.5) Quantification and localization of metallic NPs in immune competent cells is a key task for the establishment of proper dose-response correlations. A technique applicable with living cells as ultimate control will be IBM, capable of detecting single metal NPs in cells at different depths.6) Development of sophisticated cell physiological approaches focusing on the determination of oxidative activity, cytokine production and adaptive processes concerning signalling pathways beyond standard vitality tests. The research project will indicate toxic levels of various NPs and sub-toxic effects will be investigated by analysing the signalling response of immune cells