CA IX-targeted Ag₂S quantum dots bioprobe for NIR-II imaging-guided hypoxia tumor chemo-photothermal therapy

Hypoxia is the common characteristic of almost all solid tumors, which prevents therapeutic drugs from reaching the tumors. Therefore, the development of new targeted agents for the accurate diagnosis of hypoxia tumors is widely concerned. As carbonic anhydrase IX (CA IX) is abundantly distributed on the hypoxia tumor cells, it is considered as a potential tumor biomarker. 4-(2-Aminoethyl)benzenesulfonamide (ABS) as a CA IX inhibitor has inherent inhibitory activity and good targeting effect. In this study, Ag₂S quantum dots (QDs) were used as the carrier to prepare a novel diagnostic and therapeutic bioprobe (Ag₂S@polyethylene glycol (PEG)-ABS) through ligand exchange and amide condensation reaction. Ag₂S@PEG-ABS can selectively target tumors by surface-modified ABS and achieve accurate tumor imaging by the near infrared-II (NIR-II) fluorescence characteristics of Ag₂S QDs. PEG modification of Ag₂S QDs greatly improves its water solubility and stability, and therefore achieves high photothermal stability and high photothermal conversion efficiency (PCE) of 45.17%. Under laser irradiation, Ag₂S@PEG-ABS has powerful photothermal and inherent antitumor combinations on colon cancer cells (CT-26) in vitro. It also has been proved that Ag₂S@PEG-ABS can realize the effective treatment of hypoxia tumors in vivo and show good biocompatibility. Therefore, it is a new efficient integrated platform for the diagnosis and treatment of hypoxia tumors.