Unveiling the impact of the chemical composition of ternary ferrites on specific loss power

Abstract

Magnetic nanoparticles (MNPs) have been intensively investigated for their application in the therapy and diagnosis primarily of malignant diseases. In the last decade, significant research has been conducted to investigate the effectiveness of combined therapy (CT) for malignant diseases using MNPs. Our research focuses on designing a nanoplatform for combined magnetic hyperthermia and radio-nuclide therapy. We used a polyol technique to prepare binary and ternary ferrite samples. The starting components are mixed in an appropriate stoichiometric ratio to obtain samples with a nominal composition of (ZnxMn 1-x )Fe 2 O4 , (x = 0-1). ICP-OES analysis reveals a significant deviation from the nominal composition, indicating the potential formation of samples with polyvalent ions, Mn 2+/3+ and Fe 2+/3+ , as well as a possible deviation from stoichiometry with the presence of vacancies. Using the polyol synthesis method, multicore nanoflower- like nanoparticles were obtained (Figure 1a). The flower-like morphology is preserved by changing the chemical composition of the particles, so the specific properties of nanoparticles in the series mostly depend on the type and arrangement of ions at cationic sites in the crystal lattice but not on the agglomeration of crystallites in the form of nanoflowers. Nanoparticles with multicore structures resembling a flower range from 47 nm to 63 nm and crystallite sizes between 9 nm and 11 nm. It was found that iron ions within magnetite (Fe 3 O4 ) were partially substituted, with up to 27 at. % by zinc or manganese individually, and up to 22 at. % by both zinc and manganese. The samples are superparamagnetic at room temperature, with a saturation magnetization value ranging from 59 emu/g to 73 emu/g. The highest heating efficiency had a sample with composition Zn 0.098 Mn0.447 Fe 2.455 O4 (ILP was 5.77 nHm 2 /kg), Figure 1b. Using synchrotron-based high-energy X-ray powder diffraction data and PDF analysis, there are indications of local distortion at octahedral sites in the spinel crystal structure that increases with the concentration of manganese ions. Detailed structural and microstructural analysis of synthesized nanoparticles is underway. The obtained results show that it is possible to alter the physical, chemical, and colloidal properties by changing the chemical composition. This enables adjusting the efficiency of heat generation by nanoparticles when used as heat generators in magnetic hyperthermia and as carriers of radionuclides in cancer radio-nuclide therapy. Radiolabeling of the samples is our work in progress.