A degradable hydrogel formed by dendrimer-encapsulated platinum nanoparticles and oxidized dextran for repeated photothermal cancer therapy.

Hydrogels can be used to prolong the retention of photothermal agents in tumors to conduct repeated photothermal therapy (PTT) and thus reduce high-dose-induced toxicity, but the long-term retention of photothermal nanoparticles post-therapy still increases the risk of toxicity. In this work, we developed an injectable and degradable photothermal hydrogel to conduct repeated PTT. The hydrogel was composed of dendrimer-encapsulated platinum nanoparticles (DEPts) crosslinked aldehyde-modified dextran via imine bond formation. The hydrogel represented excellent photothermal effect and good biocompatibility. It was able to remain in tumors for a period of days to allow repeated PTT, leading to complete tumor regression. After treatment, the hydrogel was gradually degraded due to the decomposition of imine bonds. The study developed a practical photothermal hydrogel that allowed repeated PTT and reduced long-term retention-induced toxicity.