Synthesis of MnFe2O4 Nanoparticles and Subsequent Prussian Blue Functionalization for a Novel Composite Photothermal Material

MnFe₂O₄ magnetic nanoparticles have shown broad application prospects in the field of tumor diagnosis and treatment; however, precise particle size regulation within the 100-200 nm range, as well as the synergistic integration of physical and medical functionalities, remains challenging. As a commonly used method for synthesizing MnFe₂O₄ nanoparticles, the solvothermal method has been proven to enable the regulation of the particle size of products, particularly its ability to utilize the viscosity of solvents as a method for particle size regulation. Therefore, this work investigates the influence of the diethylene glycol (DEG) to ethylene glycol (EG) ratio on particle size regulation in solvothermal synthesis of MnFe₂O₄ nanoparticles, and constructs MnFe₂O₄@PB nanocomposite materials. The results demonstrate that with the DEG ratio increasing from 0 to 80% in a DEG:EG mixed solvent system, the average particle size of MnFe₂O₄ nanoparticles can be reduced from 266 nm to 105 nm. The MPB4.5 sample (MnFe₂O₄:PB molar ratio = 5:4.5 in the MnFe₂O₄@PB nanostructure) exhibits an optimal photothermal heating effect and good photothermal stability, demonstrating potential as a photothermal therapeutic agent. The resultant MnFe₂O₄@PB system provides a strategy for precise particle size regulation and functional integration for photothermal therapy of tumors with magnetic targeting potential.