Size Effect on MRI/MFH Relaxations by a High Anisotropic CoFe2O4-Chitosan Conjugate and Imaging/Angiography Efficacy.

We outlined cobalt ferrite (CFO) nanoparticles synthesized by chemical co-precipitation which we analyzed the structure by X-ray diffractometer (XRD) and transmission electron microscopy in the TEM and STEM mode. A STEM EDS analysis revealed elemental mapping and the stoichiometry of CoFe₂O₄. The particle sizes were in the range of 8–36 nm by heat treatment of the samples and coated with chitosan (CS). Mössbauer spectroscopy divulged the information that the inversion factor, d reduces with increasing particle size. The investigation of CSCFO nanoparticles on the Vero cell line appeared that the agents of different sizes were viable. Specific loss power of hyperthermia (SLP) depends strictly on the nanoparticle sizes and concentrations, which in turn govern the magnetic properties of CSCFO. We obtained the critical dimension as 18 nm, below which the heating mechanism was Néel and Brownian relaxation, and above 18 nm, the heating mechanism was hysteresis loss. The maximum temperature, T_max, attained by the CSCFO with the concentration as low as 1 mg/ml of particle sizes 8–36 nm are 45, 52, 55, 62, and 65 °C. A quadratic variation of r₂ relaxivity with the particle size, and linear variation with the magnetization indicates that the proton relaxation is consistent with the motional average regime (MAR). We inspected the CSCFO as contrast-enhancing dye for in vivo blood pool imaging demonstrated CSCFO as a good candidate for both positive and negative contrast dye. [ABSTRACT FROM AUTHOR]