Complete breakdown of copper-free clickable doxorubicin nanoclusters for real-time tumor proliferation tracking

•Self-assembled DOX NP co-functionalized with DBCO and DOX moieties for MMP-dependent click reaction.•Clustering of DOX NP with QD-azide depending on MMP levels the fluorescence quenching level varied accordingly.•The weight of tumor tissue homogenate affected the fluorescence dimming of the clustered DOX NP.