Comparative Magnetic Heating of Surface-Modified Ferrite Nanoparticles in Water and Agar Phantoms

This study compares the alternating-magnetic-field (AMF) heating of Fe3O4-, MnFe2O4-, MgFe2O4-, and SrFe12O19-targeted nanoparticle preparations and of their sequentially silica-modified, aminated, Aufunctionalized, and PEG-treated forms. The compositions are identified by their nominal synthesis precursors. Temperature–time curves and the times required to reach 42 °C were measured in water and in nominally 1% agar phantoms under identical induction-generator settings (132 kHz; 5 kW rated output). Among the untreated preparations, the Mg-labeled series reached 42 °C fastest (145 s in water and 187 s in agar), whereas the Srlabeled series was the slowest (222 and 293 s, respectively). For the Mg-labeled particles, increasing the concentration from 2.5 to 10 mg mL 1 shortened the time to 42 °C from 394 to 77 s in water and from 381 to 112 - s in agar. In water, the aminated Mn-, Mg-, and Sr-labeled samples heated fastest within their respective surfacetreatment series (139, 124, and 209 s), whereas the unmodified Fe-labeled core was fastest within the Fe series (171 s). The PEG-treated specimens exhibited the longest times in all four water-based series. FTIR, SEM, and EDX analyses characterized the successive surface-treatment stages, including the detection of Au after functionalization. Together, these findings clarify how precursor-defined ferrite composition, concentration, surface treatment, and surrounding medium influence magnetic heating under matched apparatus conditions.