Rechargeable Afterglow Superclusters for NIR-Excitable Repetitive Phototherapy

Abstract

Afterglow luminescence has attracted increasing attention due to its prolonged emission, reduced autofluorescence, and minimized photodamage. However, persistent luminescence typically requires high-energy excitation (e.g., ultraviolet and visible light), which has limited tissue penetration. Herein, we have developed a one-pot surface segregation strategy to construct NIR-excitable afterglow superclusters (UCZG-SCs) by modularly assembling spinel-phase afterglow nanoparticles (Zn_1.1Ga_1.8Ge_0.1O₄:Cr³⁺) and hexagonal-phase upconversion nanoparticles (NaYF₄:Yb,Tm@NaLuF₄:Y). Since the proposed methodology does not require crystal lattice similarity, it enables fabrication of various NIR-excitable persistent superclusters with great flexibility in size, composition, and luminescent profiles. As a proof of concept, an injectable persistent implant is established by embedding UCZG-SCs in the oleosol of poly(lactic-co-glycolic acid)/N-methylpyrrolidone, which serves as an inner-body lamp to excite photosensitizers for photodynamic therapy. With its excellent charging–recharging stability, a repetitive phototherapy under periodic 980 nm light illumination is accomplished, which significantly improves phototherapeutic efficiency and restrains tumor growth.