Raiders of the lost SAR: Radiofrequency cycles of magnetic nanoflowers inside a tumor

Radiofrequency magnetic cycles of ex vivo melanoma tumor tissue loaded with Fe3O4 nanoflowers (NF) were measured for several field conditions and compared with the cycles of a ferrogel (FG) obtained incorporating identical NF in agarose gel. Results were studied in order to understand a reported specific power dissipation (SAR) reduction of the NF in the actual application medium (tumor) in comparison with a typical characterization model as the FG. The linearity of the response, together with coercive field and SAR values were analyzed. Additionally, a novel method for the determination of the NF mean relaxation time is presented. Results show a systematic difference in magnetic response between the NF incorporated in the tumor and those in the FG for all field settings ({98, 170, 260} kHz and {17.4, 54.0} kA/m) with SAR reductions above 50%. •Radiofrequency magnetic cycles for Fe3O4 nanoflowers in ex vivo tumor tissue were obtained.•Nanoflowers response is different when supported in agarose gel (ferrogel).•Mean relaxation time of the particles was obtained from the cycles.•Results indicate different freedom of movement in the tumor tissue than in ferrogel.•Radiofrequency cycle measurement is demonstrated to be a powerful novel technique.