Pitfalls and Challenges in Specific Absorption Rate Evaluation for Functionalized and Coated Magnetic Nanoparticles Used in Magnetic Fluid Hyperthermia

In recent decades, considerable interest has been observed in the field of cancer treatment research in relation to magnetic hyperthermia (MH), due to its ability to target tumors and generate localized effects with a high degree of specificity. Using of biocompatible mag-netic nanoparticles, coated with specific organic molecules and functionalized with vec-torizing molecules, has enabled the targeting of particular intracellular components of the diseased tissue. The application of localized radiofrequency magnetic fields results in the excitation of magnetic nanoparticles through specific relaxation mechanisms and hyste-resis-driven processes, leading to temperatures that exceed physiological thresholds. This triggers a series of apoptosis processes. Additionally, the effects of low-frequency AC fields on high anisotropy magnetic nanoparticles, whether intra- or extracellular, have been shown to be highly effective in disrupting the internal functional structure of cells. A cru-cial parameter measuring the efficiency of magnetic nanoparticle systems in MFH is the specific absorption rate (SAR), which is experimentally evaluated by different calorimetric and magnetic techniques and methodologies. This review highlights the experimental pitfalls encountered in SAR evaluation and indicates the necessity of standardizing the devices and protocols involved in magnetic hyperthermia SAR evaluation. It also dis-cusses the challenges that arise in magnetic hyperthermia at the cellular level, pointing to a more localized and specialized magnetic hyperthermia perspective.