In vivo targeted delivery of antibodies into cancer cells with pH-responsive cell-penetrating poly(disulfide)s.

Cell-penetrating poly(disulfide)s (CPDs) are promising vehicles for cytosolic delivery of proteins. However, currently available arginine-rich CPD has rarely been reported for systemic delivery due to its "always" positive charge. Herein, we developed pH-responsive CPD IMD that executes tumor targeting delivery via protonation of imidazole groups within the acidic tumor microenvironment.