Polydopamine as the Antigen Delivery Nanocarrier for Enhanced Immune Response in Tumor Immunotherapy

This study aimed to investigate the efficacy of polydopamine nanoparticles (Pdop-NPs) as a subcutaneous antigen delivery vehicle in antitumor therapy. The nanoparticles were prepared by self-polymerization of dopamine in an aerobic and weak alkaline solution, and the tumor model antigen-ovalbumin (OVA) was grafted onto the nanoparticles to form OVA@Pdop nanoparticles (OVA@Pdop-NPs). The particle size of OVA@Pdop-NPs was 232.8 nm with a zeta potential of -23.4 mV, and the loading capacity of OVA protein was 754 μg mg^-1. OVA@Pdop-NPs were essentially noncytotoxic and even demonstrated a slightly viability effect on bone-marrow-derived dendritic cells (BMDCs). As compared to free OVA, OVA@Pdop-NPs exhibited higher cellular uptake and were easier to migrate to lymph nodes in vivo. Both in vitro and in vivo experiments showed that OVA@Pdop-NPs promoted the maturation of DCs with up-regulated expression of major histocompatibility complex (MHC), costimulatory molecules, and cytokines. When used to treat the mice bearing OVA-MC38 colon tumor, OVA@Pdop-NPs could effectively activate OVA-specific cytotoxic CD8⁺ T cells and induce the production of memory CD4⁺ and CD8⁺ T cells and thus led to significantly suppressed tumor growth. All the preliminary data demonstrated the application potential of OVA@Pdop-NPs as a vaccine vector in cancer immunotherapy.