Quantitative Understanding of Nanoscale heat Transport from iron oxide nanoparticles' surface during Hyperthermia – QUANT

Exploiting magneto-induced hyperthermia in magnetic nanomaterials has been the subject of extensive investigation for its potential applications in anti-cancer medicine, diagnostics and catalysis. Despite the extensive literature on this topic, there is still a need for a detailed understanding of the mechanisms by which these nanoparticles transfer heat to their surrounding environment. Indeed, reconciling the heat transfer time (a few nanoseconds) with the characteristic magnetic activation time (a few microseconds) is a challenging proposition. It is of great importance to gain a better understanding on the nature and kinetics of these exchanges, as recent works have clearly demonstrated the significance of local heating in the vicinity of nanoparticles, without macroscopic heating, for instance, to activate membrane proteins or activate supported catalysers. Despite several indirect attempts to estimate these thermal gradients around particles under excitation, no precise direct measurement has been proposed yet. The objective of QUANT project is to conduct a fundamental study of heat transfer around specifically manufactured magneto-fluorescent nanoparticles, with a view to comparing the experimental results obtained with a detailed modelling of these heat exchanges. By adopting a multidisciplinary approach, we will provide the scientific community with an optimized measurement methodology, adaptable to the various methods of synthesizing magnetic nanoparticles. The thermal gradients will be compared with the internal temperature of the nanoparticles, which will be measured by EXAFS on the synchrotron. Finally, and perhaps most importantly, the thermal response around nanoparticles will be described both experimentally and theoretically, with a temporal resolution provided by ultrafast fluorescence decay measurements. These measurements will help to answer the fundamental question posed by the ferrofluid community: how fast and how far heat transfer operate?