Aptamer-Conjugated Tin Oxide Nanoparticles for Noninvasive Detection of Cancer

To fundamentally address the limited tissue penetration of conventional fluorescence-based imaging, X-ray attenuation-based imaging approaches have been proposed. In this study, mesoporous tin oxide (SnO₂) nanoparticles (NPs) with a diameter of approximately 70 nm were synthesized and functionalized with PAp7T8 and HER2apt28 aptamers, which target pancreatic and breast cancer cells, respectively. The synthesized SnO₂ NPs exhibit greater X-ray attenuation than any of the tested metal oxide NPs in the tens of keV energy range corresponding to plain X-ray imaging. The surface-conjugated aptamers enable selective binding of the NPs to cancer cells, leading to efficient cellular uptake and internalization. In a model X-ray imaging experiment, as little as 5 mg of the SnO₂ NPs placed beneath 3 cm-thick biological tissues is distinctly identified with high contrast. Overall, the excellent X-ray attenuation capabilities and target specificity of these aptamer-conjugated SnO₂ NPs demonstrate their significant potential as a nanoplatform for the noninvasive imaging and diagnosis of deep-seated cancers.