Highly fluorescent sustainable SnWO₄ nanoparticles as contrast agent for computed tomography (CT)

X-ray computed tomography (CT) is extensively used in medicine and research, often requiring iodine-based contrast agents which can cause adverse effects in iodine-intolerant patients. Considering safer alternatives, we have biosynthesized and comprehensively characterized highly fluorescent tin tungstate nanoparticles (SnWO₄ NPs) with a size of 40 nm, and compared their effectiveness as contrast agents in CT imaging with that of the commercially available OMNIPAQUE^TM Iohexol injection. The comparative analysis at 80 kVp showed that the highest CT numbers at 10 mg/ml were 2106 ± 101 for iodine and 1477 ± 40 for SnWO₄ NPs, while the lowest at 1 mg/ml were 63 ± 10 and 45 ± 13, respectively. The in vitro cytotoxicity of SnWO₄ NPs against HEK-293 cells, splenocytes, and thymocytes together with their biodistribution in healthy Wistar rats was evaluated revealing minimal toxicity. These findings indicate that SnWO₄ NPs hold significant promise for biomedical imaging applications, demonstrating excellent contrast performance and positioning them as strong candidates for future use as contrast agents.