Enhancing Magnetic\nHyperthermia Efficiency in Pd/Fe-Oxide\nHybrid Nanoparticles through Mn-Doping

Multifunctional, biocompatible magnetic materials, such\nas iron\noxide nanoparticles (IONPs), hold great potential for biomedical applications\nincluding diagnostics (e.g., MRI) and cancer therapy. In particular,\nthey can play a crucial role in advancing cancer thermotherapy by\ngenerating heat when administered intratumorally and when exposed\nto an alternating magnetic field. This heat application is often combined\nwith radio- (chemo)therapy and/or imaging. Consequently, the design\nof materials for such a multimodal approach requires hybrid nanoparticles\nthat retain their magnetic properties while integrating additional\nfunctionalities. This work introduces synthesis and investigation\nof magnetically enhanced nanoparticles with a palladium core (envisioned\nfor future radiolabeling with therapeutic <sup>103</sup>Pd) and a\nmagnetic iron oxide shell containing paramagnetic manganese (Pd/Fe|(nMn)-oxide, <i>n</i> = 0.25 and 0.5). Doping the iron oxide lattice with Mn\nsignificantly increases magnetic saturation, boosting specific loss\npower up to 1.7 times compared to that of undoped analogs. Interestingly,\nhigher Mn-content in Pd/Fe|(0.5Mn)-oxide leads to a pronounced Mn\nouter rim, enhancing the heating efficiency at 346 kHz and 23 mT and\ncontributing to the water exchange on the surface of the paramagnetically\ndoped nanoparticles, resulting in additional <i>T</i><sub>1</sub> MRI contrast. The enhanced magnetic properties of the hybrid\nPd/Fe|Mn-oxide nanoparticles enable effective therapeutic outcomes\nwith injection of only small quantities of the material, offering\ngreat potential for effective cancer treatment strategies that combine\nhyperthermia/thermal ablation with radiotherapy while allowing for\nreal-time monitoring via MRI.