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Dendritic cell (DC) vaccines have shown promising effects in cancer management, while low cell activity and low migration rate to lymph nodes limit their clinical application. Here, this work reports a bioink DC vaccine, synthesized by 3D printing methacryloyl gelatin to encapsulate DCs and tumor cellular vesicles overexpressing programmed cell death protein 1 (PD1‐CVs), for cancer immunotherapy. Compared with a traditional hydrogel, the porous 3D scaffold significantly improves the viability of DCs from ∼16% to ∼70% after 7 days of cell culture and increases the proportion of released DCs from the scaffold into lymph nodes by about fourfold. The PD1‐CVs stimulate DC maturation and block PD ligand‐1 (PD‐L1) in mature DCs and tumor cells, synergistically boosting DC‐mediated antitumor immunity. In breast tumor mouse models, this personalized 3D DC vaccine developed for site‐specific filling after tumor resection significantly suppress tumor recurrence and extend median survival time to 45 days. This 3D printed vaccine offers a simple, safe, and robust strategy for enhanced cell‐based cancer immunotherapy. [ABSTRACT FROM AUTHOR]

Direct electrosynthesis of hydrogen peroxide (H2O2) via two‐electron pathway oxygen reduction reaction (2e− ORR) is crucially essential for a sustainable green economy. However, catalysts inevitably undergo four‐electron pathway oxygen reduction reaction (4e− ORR), resulting in low selectivity and economic benefits. The current challenge is to provide a feasible design strategy for obtaining satisfactory 2e− ORR catalysts with high selectivity. In this work, carbon dots (CDs) act as a cocatalyst to regulate the electron transport kinetics of In2O3/CDs, and the influence of CDs on the ORR pathways of In2O3/CDs is also studied. The electron transfer kinetics on In2O3/CDs composites are studied and analyzed using the transient photo‐induced voltage (TPV) technology. Combining the TPV results and kinetics analysis, it is shown that the electron transport on the In2O3 interface is obviously weakened after the addition of CDs, resulting in a high H2O2 selectivity. It is also demonstrated that CDs can effectively enhance the selectivity of H2O2, and the H2O2 selectivity of In2O3/CDs–10 is in close proximity to 100%, which is much higher than that of pure In2O3 (72%). This work will provide a new understanding and insight into addressing the challenge of low H2O2 selectivity for 2e− ORR catalysts. [ABSTRACT FROM AUTHOR]