X-ray microfluorescence for biodistribution studies of nanomedicines

Currently, the in vivo distribution of drugs is investigated by non-spatial quantitative techniques. With the emergence of personal therapies using nanomedicines, deeper investigations are required to precisely know the in vivo fate of entrapped drugs, especially to predict possible toxicity. Here, we assess the capabilities of SR-μXRF for i) detecting drugs into nanomedicines without adding any marker, ii) mapping their distribution into tissues and iii) locally quantifying the drugs loaded into nanomedicines. To prepare the nanomedicine model, we used the bioconjugate diamine(dichloro)platinum (SQ-CDD) developed in the TERNANOMED Grant Project. Nanomedicines were intravenously injected into a nude mice model bearing a pancreatic tumour (PANC-1). The X-ray microfluorescence experiments were performed on embeds tissue sections of kidney and tumor at 2h and 24h after nanoparticles injection. Data collection was performed on the micro-imaging beamline ID13 of the European Synchrotron Radiation Facility (ESRF). A quantitative study was performed by atomic absorption spectroscopy (AAS), allowing to compare the platinum concentrations with those measured by X-ray. This study shows that the synchrotron radiation-based μXRF analysis is sensitive enough to detect and map the distribution of a drug entrapped into nanomedicine. A quantitative local analysis is possible with a tissue element as reference, or semi-quantitatively if the tissue reference is not homogenous.