The enzyme-
responsive drug-release experiments were performed in PBS (10 mM,
pH 7.4, and pH 5.0) in triplicate for each sample, and DOX-loadednanoparticles (3 mg) were incubated in 3 mL of PBS (10 mM, pH 7.4,
and pH 5.0) with or without 20 U cathepsin B for comparison.