A 3D Macroporous Alginate Graphene Scaffold with an Extremely Slow Release of a Loaded Cargo for In Situ Long‐Term Activation of Dendritic Cells

Ex vivo manipulation of autologous antigen‐presenting cells and their subsequent infusion back into the patient to dictate immune response is one of the promising strategies in cancer immunotherapy. Here, a 3D alginate scaffold embedded with reduced graphene oxide (rGO) is proposed as a vaccine delivery platform for in situ long‐term activation of antigen‐presenting dendritic cells (DCs). High surface area and hydrophobic surface of the rGO component of the scaffold provide high loading and a very slow release of a loaded antigen, danger signal, and/or chemoattractant from the scaffold. This approach offers long‐term bioavailability of the loaded cargo inside the scaffold for manipulation of recruited DCs. After mice are subcutaneously vaccinated with the macroporous alginate graphene scaffold (MAGS) loaded with ovalbumin (OVA) and granulocyte‐macrophage colony‐stimulating factor (GM‐CSF), this scaffold recruits a significantly high number of DCs, which present antigenic information via major histocompatibility complex class I for a long period. Furthermore, an MAGS loaded with OVA, GM‐CSF, and CpG promotes production of activated T cells and memory T cells, leading to the suppression of OVA‐expressing B16 melanoma tumor growth in a prophylactic vaccination experiment. This study indicates that an MAGS can be a strong candidate for long‐term programming and modulating immune cells in vivo.