Zwitterionic rhodamine-CPT prodrug nanoparticles with GSH/HO responsiveness for cancer theranostics.

Fluorescently traceable prodrugs, which can monitor their biodistribution and track the kinetics of drug delivery in living cells, are promising for constructing theranostic medicines. However, due to their charge and hydrophobicity, most of the fluorescently traceable prodrugs exhibit high protein binding and non-specific tissue retention affecting distribution and toxicity, with high background signals. Herein, the zwitterionic rhodamine (RhB) and camptothecin (CPT) were bridged with a disulfide bond to construct a tumorous heterogeneity-activatable prodrug (RhB-SS-CPT).