CAT and neoplasm: The tumor hypoxia has been demonstrated to lower the chemotherapeutic efficacy.[64, 65, 66] In order to alleviate the tumor hypoxia and enhance the chemotherapeutic outcome of doxorubicin (DOX), an oxygen‐generating depot was constructed by directly encapsulating CaO2 nanoparticles and catalase into the matrix of alginate pellets (Figure 4a).[67] After the implantation of this multifunctional alginate pellet into the tissue close to tumor, the reaction of CaO2 and H2O initially produced H2O2.