Molecular Imaging Contrast Properties Of Fe3o4-Au Hybrid Nanoparticles For Dual-Mode Mr/Ct Imaging Applications

The development of noninvasive testing techniques in medicine by combining dual-mode Magnetic Resonance (MR)/ Computed Tomography (CT) imaging techniques will help overcome the limitations of the separated methods, leading to more accurate diagnoses. This has implications in clinical research, but currently remains a major challenge in terms of the need for a corresponding multimodal signal contrast agent. In this study, we use small size, monodispersed Fe3O4 magnetic nanoparticles as the seeds to synthesize magneto-plasmonic Fe3O4@Au hybrid nanoparticles (HNPs) with multiple functions with core-shell structures. The influence of the ratios of HAuCl4 and oleyamine (OLA) precursors on the shape and size of the nanoparticles (NPs) was investigated. The HAuCl4/OLA ratio of 0.2/1 is the optimal condition. The obtained NPs has an average size of 21.2 nm with a uniform spherical shape, high monodispersity. After the surface functionalization with poly(acrylic acid) (PAA), the resulting Fe3O4@Au@PAA HNPs showed excellent dispersion in water, good biocompatibility, non-toxicity against Hep-G2 cancer cell line and Vero healthy cell line at high test concentration. The In-vitro test data showed that the materials with Au shell enhance X-ray decrease even at low concentrations compared to iodine-based commercial substances while retaining the same effect as T-2 contrast agent with high transverse relaxation rate r(2) (125.2 mM(-1)s(-1)). The In-vivo MRI images of rat liver tissue demonstrated that the hybrid nanoparticles showed the contrast increases 3 times under 1.5 T magnetic field after 30 minutes of drug administration. The computed tomography measurements showed the highest Hounsfield unit (HU) of 133.5 after the hybrid nanoparticle injected for 30 minutes. The in-vivo efficacy of Fe3O4@Au@PAA magneto-plasmonic hybrid nanoparticles was further evaluated in the cardiac and renal organs in a mouse test model to study drug kinetics. Generally, these Fe3O4@Au@PAA hybrid nanomaterials showed great promise as a candidate for multi-modality molecular bio-imaging.