Preparation and characterization of SPION functionalized via caffeic acid

Caffeic acid coated superparamagnetic iron oxide nanoparticles (SPION-CFA) was synthesized by reflux method. The structural, spectroscopic and magnetic properties were studied by X-ray diffraction (XRD), Transmission electron microscopy (TEM), Scanning electron microscopy (SEM), and Vibrating sample magnetometer (VSM) techniques. Thermal gravimetric analysis (TG) and Fourier transform infrared spectroscopy (FT-IR) confirmed the presence of CA on the surface of SPION. The theoretical analyzes performed on recorded room temperature VSM spectrum confirmed the formation of superparamagnetic nature of SPION-CFA. The particle size dependent Langevin function was applied to determine the average magnetic particle dimension (Dmag) around 11.93 nm. In accordance, the average crystallite and particle sizes were obtained as 11.40 nm and ~12.00 nm from XRD and TEM measurements. The extrapolated specific saturation magnetization (σs) is 44.11 emu/g and measured magnetic moment is 1.83 µB. These parameters assign small order of magnetization for NPs with respect to bulk Fe3O4. Magnetic anisotropy was offered as uniaxial and calculated effective anisotropy constant (Keff) is 34.82×104 Erg/g. The size-dependent saturation magnetization suggests the existence of a magnetically inactive layer as 1.035 nm for SPION-CFA.