Textural Thermo-gravimetric and Magnetic Properties of Green Synthesised Water Dispersible Pristine and Gold Coated Superparamagnetic Iron Oxide Nanoparticles

Abstract

Gold-coated magnetic nanoparticles have received a lot of attention in recent years due to their multifunctional attributes and their prospective unique characteristics in environmental and biomedical applications. This paper reports the textural, thermo-gravimetric, and magnetic properties of green synthesized gluconic acid-capped uncoated and gold-coated superparamagnetic iron oxide nanoparticles (SPION@Au). The as-synthesized nanomaterials were characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDX), thermal gravimetric analysis (TGA), Brunauer–Emmett–Teller (BET), and superconducting quantum interference device (SQUID) magnetometry. The XRD and SEM measurements showed that the gluconic acid-capped magnetic core was coated with gold with cubical spinel crystalline structures. TGA results revealed the thermal stability of the nanoparticles. Textural properties indicated that the gold-coated nanoparticles were in naturally mesoporous and exhibited the type IV isotherm with an H2 hysteresis loop. The estimated maximum pore diameter and surface area of SPION@Au were 3.33 nm and 134.02 m²/g respectively. Furthermore, the SQUID results showed the nanocrystals were superparamagnetic with a blocking temperature (TB) of 214 K at 500 Oe and saturation magnetization of 11.38 emu/g. These noteworthy results demonstrated that the as-synthesized SPION@Au are promising nanomaterials for biomedical and analytical applications.