Mutual Benefit between Cu(II) and Polydopamine for Improving Photothermal-Chemodynamic Therapy.

Combination therapy has attracted extensive interest in alleviating the shortcomings of monotherapy and enhancing the treatment efficacy. In this work, hollow mesoporous silica nanoparticles (HMSNs) play the role of nanocarriers in the delivery of Cu(II)-doped polydopamine (PDA), termed as HMSNs@PDA-Cu, for synergistic therapy. PDA acts as a traditional photothermal agent to realize photothermal treatment (PTT). Chemodynamic therapy (CDT) is realized by the reaction of Cu(II) with intracellular glutathione (GSH), and subsequently, the generated Cu(I) reacts with H ₂ O ₂ to produce toxic hydroxyl radical ( ^• OH) through a Fenton-like reaction. The photothermal performance of PDA is improved after its coordination with Cu(II). On the other hand, PDA exhibits superoxide dismutase (SOD)-mimicking activity. PDA converts O ₂ ^{• -} to H ₂ O ₂ and improves the production of H ₂ O ₂ , which promotes the therapeutic effect of CDT. Moreover, the high temperature caused by PTT further enhances the yield of ^• OH for CDT. This nanotheranostic platform perfectly applied to the tumor depletion of mice, presenting great potential for cancer metastasis therapy in vitro and in vivo.