Gold decorated bismuth sulfide nanorods for enhanced computed tomography imaging with in vitro and in vivo validation

The development of hybrid metal nanoparticles (NPs) for use as computed tomography (CT) contrast agents is a promising area of research. Achieving optimal in vivo performance of imaging for NPs is challenging and depends on their geometry, materials properties, bioreactivity, and biocompatibility. In this study, we designed and developed a novel CT contrast agent composed of gold nanoparticles (AuNPs) coordinated on the surface of bismuth sulfide-core nanorods (Au@Bi₂S₃ NRs) utilizing a solvothermal synthesis approach. We conducted solid-state characterization of Au@Bi₂S₃ NRs, demonstrating their structural configuration, excellent stability, uniformity, and high crystallinity. We also tested their biocompatibility with mesenchymal stem cells and found that they were well tolerated at lower tested concentrations, with reduced viability observed at higher concentrations. To evaluate the imaging potential of Au@Bi₂S₃ NRs, we tested them in small animals using CT imaging. Our results showed contrast enhancement in soft tissues, indicating the retention of the particles at these locations with no local inflammatory responses. Taken together, our study provides a proof-of-concept for the robust synthesis and use of Au@Bi₂S₃ NRs as effective CT imaging contrast agents. Future work will explore the potential to functionalize Au@Bi₂S₃ NRs with therapeutic molecules for theranostic applications.