Enzyme‐Activatable Polypeptide for Plasma Membrane Disruption and Antitumor Immunity Elicitation

Abstract Enzyme‐instructed self‐assembly of bioactive molecules into nanobundles inside cells is conceived to potentially disrupt plasma membrane and subcellular structure. Herein, an alkaline phosphatase (ALP)‐activatable hybrid of ICG‐CF₄KY^p is facilely synthesized by conjugating photosensitizer indocyanine green (ICG) with CF₄KY^p peptide via classical Michael addition reaction. ALP‐induced dephosphorylation of ICG‐CF₄KY^p enables its transformation from small‐molecule precursor into rigid nanofibrils, and such fibrillation in situ causes severe mechanical disruption of cytomembrane. Besides, ICG‐mediated photosensitization causes additional oxidative damage of plasma membrane by lipid peroxidation. Hollow MnO₂ nanospheres devote to deliver ICG‐CF₄KY^p into tumorous tissue through tumor‐specific acidity/glutathione‐triggered degradation of MnO₂, which is monitored by fluorescent probing and magnetic resonance imaging. The burst release of damage‐associated molecular patterns and other tumor antigens during therapy effectively triggers immunogenetic cell death and improves immune stimulatory, as demonstrated by the promotion of dendritic cell maturation and CD8⁺ lymphocyte infiltration, as well as constraint of regulatory T cell population. Taken together, such cytomembrane injury strategy based on peptide fibrillation in situ holds high clinical promise for lesion‐specific elimination of primary, abscopal, and metastatic tumors, which may enlighten more bioinspired nanoplatforms for anticancer theranostics.