Microfocus x-ray fluorescence mapping of tumour penetration by an organo‑osmium anticancer complex.

Microfocus synchrotron x-ray fluorescence (SXRF) imaging focussed on detection of the Os LIII edge shows that the organo‑osmium metallodrug candidate [(ŋ6-p-cym)Os(Azpy-NMe2)I]+ (p-cym = p-cymene, Azpy-NMe2 = 2-(p-([dimethylamino]phenylazo)pyridine)) [1] penetrates efficiently into the interior of A2780 human ovarian cancer cell spheroids, a model for a solid tumour. The accompanying changes in Zn and Ca distribution suggest that the complex causes nuclear damage and initiates signalling events for cell death, consistent with findings for cultured cancer cell monolayers. Such tumour penetration is likely to be important for combatting resistance to chemotherapy, which is becoming a problem for current clinical platinum drugs.