In vitro CT imaging and cellular evaluation of hyaluronic acid-functionalized Bi₂S₃@BSA nanoparticles

The development of high-atomic-number (high-Z) nanomaterials as computed tomography (CT) contrast agents has attracted considerable interest because of their strong X-ray attenuation. In this study, hyaluronic acid (HA)-functionalized bismuth sulfide nanoparticles (Bi₂S₃@BSA-HA) were synthesized and characterized, and their CT imaging performance was evaluated over a tube-voltage range of 80-130 kVp. CT attenuation was assessed as a function of Bi concentration and tube voltage and compared with non-functionalized Bi₂S₃@BSA nanoparticles and the clinical iodinated contrast agent Omnipaque. Contrast-to-noise ratio (CNR), cytocompatibility, and in vitro cellular CT imaging were also evaluated. Bi₂S₃@BSA-HA exhibited significantly higher CT attenuation than both Bi₂S₃@BSA and Omnipaque, reaching 146.8 ± 6.9 HU at 1.5 mg Bi mL^-1 and 80 kVp. CT attenuation increased linearly with Bi concentration (R² > 0.93) and decreased with increasing tube voltage. The HA-functionalized nanoparticles consistently exhibited higher CNR values across all investigated tube voltages. MTT assays demonstrated low cytotoxicity, with cell viability exceeding 90% after 24 h. In vitro cellular CT imaging showed higher CT numbers and CNR in HT-29 cells incubated with Bi₂S₃@BSA-HA than with Bi₂S₃@BSA. These findings demonstrate improved in vitro CT imaging performance with good cytocompatibility under the investigated conditions.