EGFR and cancer: Considering that tumor cells continuously secrete proton, lactate and carbon dioxide into the extracellular tumor microenvironments [24], tumor-accumulated Doxy@CaCO3-PEG is hypothesized to undergo gradual degradation alongside engulfment by cancer cells (Fig. S14), thereby enabling sustained Doxy release for the effective localized activation of Tet-HER1-CAR-T cells within tumors.