Excellent relaxivity and X-ray attenuation combo properties of Fe3O4@Au CSNPs produced via Rapid sonochemical synthesis for MRI and CT imaging

Core@shell nanoparticles (Fe3O4@Au CSNPs) have multiple functions obtained in one stable entity and thus have been extensively investigated. Fe3O4 NPs have unique superparamagnetic properties which allow for their application in different fields, and Au NPs stand out in biomedical applications because of their chemical stability, oxidation resistance and high-quality intrinsic optical properties. Combining Fe3O4 and Au NPs in one core@shell nanostructure is a promising strategy for diagnostic biomedical applications. However, the conventional direct methods for Fe3O4@Au CSNP synthesis are laborious and time consuming. Therefore, this study presents a facile and rapid sonochemical technique of synthesising Fe3O4@Au CNPs with excellent physicochemical properties for magnetic resonance imaging (MRI) and computed tomography (CT) scan. A Vibra Cell ultrasonic solid horn with a tip size of 1/2 inch, 20 kHz frequency and power output of 750 W were used, and the synthesis is achieved in just 10 min. Several techniques were used to characterise the Fe3O4@Au CSNPs and confirmed their average size of 21 nm and the formation of spherical Au shell on the Fe3O4 core. The Fe3O4@Au CNPs showed good biocompatibility and great potential as a dual-mode contrast agent for MRI/CT imaging. The transverse relaxivity values and X-ray attenuation of the as-synthesised NPs (222.28 mM(-1)s(-1) and HU = 418) are greater than those of NPs prepared using conventional methods and commercial NPs. This work reveals considerable progress on Fe3O4@Au CSNPs by providing a facile and rapid method to synthesise high-quality Au-coated Fe3O4 NPs.