Nanoclusters of crystallographically aligned nanoparticles for magnetic thermotherapy: aqueous ferrofluid, agarose phantom and ex vivo melanoma tumour assessment

CORAL CORAL, DIEGO FERNANDO; SOTO, PAULA ANDREA ANDREA; BLANK, VIVIANA; VEIGA, ALEJANDRO; SPINELLI, ENRIQUE; GONZALEZ, SERGIO; SARACCO, GUSTAVO PABLO ; BAB, MARISA ALEJANDRA; MURACA, DIEGO; SETTON-AVRUJ, PATRICIA C.; ROIG, ANNA; ROGUIN, LP; FERNÁNDEZ VAN RAAP, MARCELA B. B.

Nanoscale

Royal Society of Chemistry

Año: 2018 vol. 10 p. 21262 - 21274

2040-3364

Magnetic hyperthermia is an oncologic therapy where magnetic nanostructures, under a radiofrequency field, act as heat transducers increasing tumour temperature and killing cancerous cells. Nanostructure heating efficiency depends both on the field conditions and on the nanostructure properties and mobility inside the tumour. Such nanostructures are often incorrectly bench-marketed in colloidal state and using field settings far off from the recommended therapeutic values. Here, we prepared nanoclusters composed of iron oxide magnetite nanoparticles crystallographically aligned and their specific absorption rate (SAR) values were calorimetrically determined in physiological fluids, agarose-gel-phantoms and ex vivo tumours extracted from mice challenged with B16-F0 melanoma cells. A portable, multipurpose applicator using medical field settings; 100 kHz and 9.3 kA m-1, was developed and the results were fully analysed in terms of nanoclusters structural and magnetic properties. A careful appraisal of the nanoclusters heating capacity in the three milieus clearly indicate that the SAR values of fluid suspensions or agarose-gel-phantoms are not adequate to predict real tissue temperature rise or the dosage needed to heat a tumour. Our results show that besides nanostructure mobility, perfusion and local thermoregulation, nanostructures distribution inside the tumour plays a key role in the effective heating. A suppression of magnetic material effective heating efficiency appears in tumour tissue. In fact, dosage had to be much increased, from the SAR values predicted from fluid or agarose to achieve the desired temperature increase. These results represent an important contribution towards the design of more efficient nanostructures and towards clinical translation of hyperthermia.