Near-Infrared Phosphorescence Micelles with λ_em > 800 nm Constructed by Block Copolymers and Platinum(II) Complexes:...

Luminescence platinum(II) complexes have demonstrated significant potential as highly efficient theranostic probes that integrate bioimaging and chemotherapeutic capabilities. The construction of platinum(II) complexes-based supramolecular nanoprobes that are capable of both deep-penetrating NIR bioimaging (>800 nm) and tumor chemotherapy is a highly attractive but significantly challenging task. In this study, a series of polymer micelles exhibiting enhanced NIR phosphorescence emission were prepared via electrostatic self-assembly between cationic platinum(II) complexes with anionic poly(acrylate sodium) blocks in water. The platinum(II) complexes in the micellar cores exhibited high aggregation tendency in aqueous solution, which is driven by Pt(II)···Pt(II) and π-π stacking interactions and further promoted by the electrostatic interactions. Consequently, the platinum(II)-containing polymer micelles E₁₃₆A₂₈-1e and E₁₃₆A₂₈-3 showed intense NIR emission bands at 836 and 898 nm with high quantum yields and large Stokes shifts, respectively. Benefiting from their superior NIR phosphorescence and anticancer activity in vitro, E₁₃₆A₂₈-1e and E₁₃₆A₂₈-3 displayed excellent NIR imaging of tumor tissues in vivo, permitting the visualization of drug accumulation in tumor areas and the in situ killing of cancer cells without harming healthy organs. This work provides an extraordinary opportunity to create Pt-based nanomedicines with NIR luminescence applied for cancer theranostics.