A glutathione-activated NIR-II fluorescent probe for precise localization of micrometastases

Accurate detection and localization of micrometastases are extremely important for tumor diagnosis and comprehensive treatment. However, it is clinically difficult to finely localize micrometastases, especially focal lesions smaller than 1 mm. To that purpose, this work designed a tumor microenvironment factor (glutathione, GSH)-activated second near-infrared transparency window (NIR-II) fluorescent probe for visualization of micrometastases. It is constructed by complexing copper ions with 3-mercaptopropionic acid-modified silver sulfide (Ag2S-MPA) quantum dots. The experimental results showed that the probe has good and stable GSH activation properties and can achieve tumor-specific NIR-II fluorescence imaging. Further, in vivo imaging experiments demonstrated that the probe can precisely localize melanomas with a diameter of < 0.1 mm in lung micrometastases. This work provides a potential strategy for the development of novel tools for localization and visualization of micrometastases.