Radionuclide 188 Re‐Loaded Photothermal Hydrogel for Cancer Theranostics

Herein, an injectable photothermal hydrogel system containing a therapeutic radionuclide 188 Re is studied for combined radioisotope therapy and photothermal therapy (PTT) of cancer. A dopamine‐conjugated poly(α,β‐aspartic acid) copolymer (PDAEA) is used to trigger a sol–gel phase transition in mixture with Fe 3+ ions, rapidly forming a gel by simply mixing PDAEA and FeCl 3 phosphate buffer saline solutions. The injectable hydrogel exhibits strong near‐infrared light absorbance and can efficiently convert light into a heating effect for local PTT treatment. The obtained hydrogel possesses a porous 3D microstructure, and can be utilized for radionuclide loading. After the Na 188 ReO 4 loading, the hydrogel is intratumorally injected into the tumor of mice bearing 4T1 murine breast cancer cells for studying the tumor retention and therapeutic efficiency. In vivo results show that Na 188 ReO 4 ‐loaded hydrogel exhibits significantly longer time in the tumor sites than that of free Na 188 ReO 4 . The tumor growth of mice treated with Na 188 ReO 4 ‐loaded hydrogel under near‐infrared radiation is significantly inhibited compared with control groups. Therefore, the results show that the developed strategy using an injectable and biocompatible hydrogel may promote the applications of radioisotope therapy and photothermal therapy for cancer.