Polydopamine nanoparticles cross-linked hyaluronic acid photothermal hydrogel with cascading immunoinducible effects for in situ antitumor vaccination.

Tumor vaccine, which can effectively prevent tumor recurrence and metastasis, is a promising tool in tumor immunotherapy. However, heterogeneity of tumors and the inability to achieve a cascade effect limit the therapeutic effects of most developing tumor vaccine. We have developed a cascading immunoinducible in-situ mannose-functionalized polydopamine loaded with imiquimod phenylboronic hyaluronic acid nanocomposite gel vaccine (M/P-PDA@IQ PHA) through a boronic ester-based reaction. This reaction utilizes mannose-functionalized polydopamine loaded with imiquimod (M/P-PDA@IQ NAs) as a cross-linking agent to react with phenylboronic-grafted hyaluronic acid. Under near-infrared light irradiation, the M/P-PDA@IQ PHA caused local hyperthermia to trigger immunogenic cell death of tumor cells and tumor-associated antigens (TAAs) releasing. Subsequently, the M/P-PDA@IQ NAs which were gradually released by the pH/ROS/GSH-triggered degradation of M/P-PDA@IQ PHA, could capture and deliver these TAAs to lymph nodes. Finally, the M/P-PDA@IQ NAs facilitated maturation and cross-presentation of dendritic cells, as well as activation of cytotoxic T lymphocytes. Overall, the M/P-PDA@IQ PHA could serve as a novel in situ vaccine to stimulate several key nodes including TAAs release and capture, targeting lymph nodes and enhanced dendritic cells uptake and maturation as well as T cells activation. This cascading immune activation strategy can effectively elicit antitumor immune response.