Facile Preparation of Multifunctional WS2/WOx Nanodots for Chelator-Free 89Zr-Labeling and In Vivo PET Imaging

While position emission tomography (PET) is an important molecular imaging technique for both preclinical research and clinical disease diagnosis/prognosis, chelator-free radiolabeling has emerged as a promising alternative approach to label biomolecules or nanoprobes in a facile way. Herein, starting from bottom-up synthesized WS2 nanoflakes, this study fabricates a unique type of WS2/WOx nanodots, which can function as inherent hard oxygen donor for stable radiolabeling with Zirconium-89 isotope (Zr-89). Upon simply mixing, Zr-89 can be anchored on the surface of polyethylene glycol (PEG) modified WS2/WOx (WS2/WOx-PEG) nanodots via a chelator-free method with surprisingly high labeling yield and great stability. A higher degree of oxidation in the WS2/WOx-PEG sample (WS2/WOx (0.4)) produces more electron pairs, which would be beneficial for chelator-free labeling of Zr-89 with higher yields, suggesting the importance of surface chemistry and particle composition to the efficiency of chelator-free radiolabeling. Such Zr-89-WS2/WOx (0.4)-PEG nanodots are found to be an excellent PET contrast agent for in vivo imaging of tumors upon intravenous administration, or mapping of draining lymph nodes after local injection.