The concentration of trace elements in human tissues and fluids usually presents narrow ranges of variation and therefore represents a good biochemical marker. Iron levels in erythrocytes and blood serum are also an example of a similar case. The excess or deficiency of certain trace elements within a human biological system might be accompanied by toxic syndromes or diseases, although the exact role of trace elements has not been clearly understood. Generally, the concentrations of elements in human biological systems are very small, from a few micrograms to a few nanograms or less per gram of sample. Laboratory and synchrotron based XRF analysis, often combined with specialized sample preparation methodologies, can provide the required analytical performance to quantify the trace elements concentration but also to reveal their spatial distribution at tissue or even at cellular/sub-cellular level.
Previous research in the field was conducted related to the study of potassium-rubidium and calcium-strontium metabolism in humans in collaboration with the Medical School of the University of Athens (first Propaedeutic Clinic). XRF analysis was used to determine calcium, strontium, potassium and rubidium in selected dietary products, blood serum and urine in both healthy and sick people with chronic renal failure and in patients undergoing continuous peritoneal dialysis). The PIGE technique was used for the determination of fluorine in human healthy and carious teeth in order to determine and compare the concentration of fluorine in different types of teeth (segments, premolars, molars) within two different populations with similar dietary habits, professional occupations (mainly rural) and average age, but consuming drinking water of different fluorine concentration levels. Other studies were focused to investigate the exposure of humans to uranium (through preconcentrated urine TXRF analysis), barium and of other metals due to environmental or occupational related factors.
XRF applications in pharmaceutics are currently developed in collaboration with the Department of Pharmaceutical Technology of the University of Patras. This research is aimed to the study of the biodistribution of cisplatin drugs in the blood and tissues of laboratory animals. For example the Pt concentration level was determined in a complete series of lyophilized blood samples and the function of PLGA-mPEG platinum nanoparticles and aqueous cisplatin solution was comparatively evaluated. Further on, the efficacy of Pt based anticancer drug delivery systems was studied on different animal organs by assessing their enhanced cytotoxic properties to tumorous tissues and the reduced toxicity to other organs. The XRF measurements provided a very useful contribution to the design and development of cisplatin drug delivery systems.
Finally, within an international collaboration, the emerging potential of XRF elemental imaging was investigated towards histopathological analysis. In this work, the methodology was evaluated for the differentiation of different stages of ovarian tumour tissues. Statistical methods, such as the K-means clustering and non-negative matrix factorization were applied to achieve proper segmentation of the acquired elemental images to allow a valid comparison with the results of the histopathological examination.