Conjugated Polymer Brush Based on Poly(l-lysine) with Efficient Ovalbumin Delivery for Dendritic Cell Vaccine

Dendritic cell (DC)-based vaccines consist of antigens and antigen-presenting cells, such as DCs, that can induce antitumor immune response and extend the lives of patients. In this research, a water-soluble conjugated polymer brush (WSCPB) made of poly(l-lysine) (PLL) and poly(p-phenyleneethynylene) (PPE) was applied to an antigen delivery system for the development of a DC vaccine. We synthesized the WSCPB with a lower proportion of the rigid PPE polymer backbone and a large amount of PLL side chains. The rigid backbone retained a stable optical performance within the experimental range, which enabled the visualization of the payload and cellular imaging as a reporter. Because of the unique brushlike structure, PPE-PLL exhibited not only excellent water solubility but also outstanding antigen-loading capacity. Ovalbumin (OVA), a model antigen in different research, could be adsorbed onto PPE-PLL and then taken up by DCs. Subsequently, DC maturation and cytokine release would be induced by the antigen. In vivo, strong immune responses were induced after the injection of antigen-pulsed DCs, and the level of cytokines in the serum was significantly increased. In addition, the study of the in vivo tumor-suppressor activity of these antigen-pulsed DCs revealed that the DC vaccine induced strong immune responses and thereby effectively inhibited tumor development.