Design of CTAB-Coated Ni_xFe_3−xO₄ Magnetic Nanoparticles as Magnetic Particle Imaging (MPI) Tracers

Recent advancements in nanotechnology have rapidly promoted research on developing novel nano-sized MNPs with satisfactory biocompatibility for biomedical applications. This study synthesized Ni_xFe_3−xO₄ MNPs (with x = from 0 to 1.0) coated with CTAB with hydrothermal and coprecipitation methods for the medical imaging systems as a tracer agent. The structural properties of the CTAB-coated Ni_xFe_3−xO₄ MNPs, including the crystalline lattice, composition, and morphological pattern, are characterized with an X-ray, SEM, and EDS, and the results confirmed the formation of highly crystalline magnetite of spherical shaped NPs in the presence of CTAB. The cell constant and average crystallite size of CTAB-coated Ni_xFe_3−xO₄ MNPs are determined as 8.33–8.40 nm and 10.5–18.6 nm, respectively. FT-IR is recorded to detect the presence of NH₂ and CH bands, confirming a successful CTAB coating. The saturation magnetization of the particles is measured as between 50–80 emu g⁻¹ with a PPMS. The dynamic response of the tracer agents to the alternating magnetic fields is also determined with an MPS at 9.9 kHz. Effective relaxation time, FWHM of the nanoparticle's signals, and frequency spectrum are evaluated. MTT analysis indicates the low cytotoxicity and high biocompatibility of CTAB-coated NiFe₂O₄ NPs.