Mn²⁺-coordinated PDA@DOX/PLGA nanoparticles as a smart theranostic agent for synergistic chemo-photothermal tumor therapy

Nanoparticle drug delivery carriers, which can implement high performances of multi-functions, are of great interest, especially for improving cancer therapy. Herein, we reported a new approach to construct Mn²⁺-coordinated doxorubicin (DOX)-loaded poly(lactic-co-glycolic acid) (PLGA) nanoparticles as a platform for synergistic chemo-photothermal tumor therapy. DOX-loaded PLGA (DOX/PLGA) nanoparticles were first synthesized through a double emulsion-solvent evaporation method, and then modified with polydopamine (PDA) through self-polymerization of dopamine, leading to the formation of PDA@DOX/PLGA nanoparticles. Mn²⁺ ions were then coordinated on the surfaces of PDA@DOX/PLGA to obtain Mn²⁺-PDA@DOX/PLGA nanoparticles. In our system, Mn²⁺-PDA@DOX/PLGA nanoparticles could destroy tumors in a mouse model directly, by thermal energy deposition, and could also simulate the chemotherapy by thermal-responsive delivery of DOX to enhance tumor therapy. Furthermore, the coordination of Mn²⁺ could afford the high magnetic resonance (MR) imaging capability with sensitivity to temperature and pH. The results demonstrated that Mn²⁺-PDA@ DOX/PLGA nanoparticles had a great potential as a smart theranostic agent due to their imaging and tumor-growth-inhibition properties.