Micro-XANES analysis of superparamagnetic iron-oxide nanoparticles in biological tissues

Highlights: • μXRF located the areas of high Fe concentration in mice lungs after SPIONs injection. • μXANES distinguished contributions from SPIONs and native iron in the lung tissue. • SPIONs showed chemical and structural stability after in vivo application. Micro - X-ray Absorption Near Edge Structure (μXANES) at the Fe K-edge of biological tissues after admission of superparamagnetic iron oxide nanoparticles (SPIONs) has been used to monitor the iron oxidation state in the nanoparticles and in the native tissues. It was found that μXANES technique with submicron spatial resolution is sensitive enough to allow a separation of the contributions from the iron atoms present in SPIONs from the contribution of the atoms representing iron contained in the tissues of the body before the introduction of nanoparticles. The analysis of μXANES showed that SPIONs studied in the present research is found to be quite stable and retains its properties after interaction with tissues in vivo. Thus, such SPIONs are promising for further use in the theranostics for oncology.