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 OMNIPAQUETM 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.