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

Abstract

Radiofrequency magnetic cycles of \textit{ex vivo} melanoma tumor tissue loaded with Fe$_3$O$_4$ 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\%.