Controllable Self‐Assembly of V═O Metalloradical Complex with Intramolecular Charge Transfer for Enhanced NIR‐II Fluorescence Imaging‐Guided Photothermal Therapy

Centered metalloradical boosting charge transfer introduces additional nonradiative energy dissipation pathways. Vanadyl metalloradical naphthalocyanine nanoparticles demonstrate near-infrared second-region absorption and fluorescence, achieving a photothermal conversion efficiency of 46.6%, which surpasses that of closed-shell ZnNc naphthalocyanine nanorods at 38.8%. These findings provide valuable insights for the development of efficient single-material integrated nanosystems for diagnostic and therapeutic applications.

Abstract

Near-infrared second region (NIR-II) fluorescence imaging provides enhanced tissue penetration, achieving efficient NIR-II fluorescence and photoacoustic imaging (PA)-guided photothermal therapy (PTT) all in one material remains a challenging yet promising approach in cancer treatment. Herein, open-shell V═O metalloradical complex (VONc) is self-assembled into VONc nanospheres (VONc NPs). VONc NPs exhibit light absorption from 300 to 1400 nm, fluorescence spectra ranging from 900 to 1400 nm, and a distinct fluorescence signal even at 1550 nm. Moreover, VONc NPs exhibit outstanding photostability and a higher photothermal conversion efficiency of 46.6% than that of closed-shell zinc naphthalocyanine nanorods (ZnNc NRs). V═O centered metalloradical serves as transient electron-withdrawing groups to facilitate charge transfer (CT), introducing additional nonradiative energy dissipation pathways and enhancing efficient heat generation. In vitro experiments of VONc NPs indicate that a highly effective photothermal action causes harm to both mitochondria and lysosomes, resulting in the death of tumor cells, closed-shell ZnNc NPs exhibit almost no cell killing as contrast. In vivo anti-tumor therapy results of VONc NPs demonstrate excellent NIR-II fluorescence imaging-guided PTT against tumors with a favorable biosafety profile. “Centered metalloradical boosting CT” toward open-shell metal complexes provides significant insight for developing single-material integrated nanosystems for diagnostic and therapeutic applications.