CTSB and neoplasm: Moreover, in order to facilitate the effect of drug on the tumor, Tan et al. designed an enzyme-responsive multifunctional nanoparticle, poly (OEGMA)-PTX prodrug@Ce6 (NPs@Ce6), composed of a photosensitizer chlorin e6 (Ce6) and a cathepsin B-responsive polymer-paclitaxel (PTX) prodrug by self-assembly (Fig. 4d) [49].