Rechargeable Afterglow Superclusters for NIR-Excitable Repetitive Phototherapy

Area of Science:

• Materials Science
• Nanotechnology
• Biomedical Engineering

Background:

• Afterglow luminescence offers prolonged emission, reduced autofluorescence, and minimized photodamage, making it attractive for biomedical applications.
• Current persistent luminescence often requires high-energy excitation (UV/visible light), limiting tissue penetration and therapeutic efficacy.
• A need exists for afterglow materials excitable by near-infrared (NIR) light for deeper tissue penetration.

Purpose of the Study:

• To develop novel NIR-excitable afterglow superclusters (UCZG-SCs) for enhanced photodynamic therapy (PDT).
• To demonstrate a flexible fabrication strategy for tunable supercluster properties.
• To create an injectable implant for in-body PDT applications.

Main Methods:

• A one-pot surface segregation strategy was employed to assemble spinel-phase (Zn_1.1Ga_1.8Ge_0.1O₄:Cr³⁺) and hexagonal-phase (NaYF₄:Yb,Tm@NaLuF₄:Y) nanoparticles into NIR-excitable afterglow superclusters.
• The methodology allows for flexible fabrication of superclusters with varying size, composition, and luminescent profiles, independent of crystal lattice similarity.
• An injectable persistent implant was created by embedding UCZG-SCs in a poly(lactic-co-glycolic acid)/N-methylpyrrolidone oleosol.

Main Results:

• Successfully constructed NIR-excitable afterglow superclusters (UCZG-SCs) with excellent charging-recharging stability.
• Demonstrated the feasibility of an injectable persistent implant for in-body PDT.
• Achieved repetitive phototherapy under periodic 980 nm light illumination, significantly improving phototherapeutic efficiency and restraining tumor growth.

Conclusions:

• The developed one-pot strategy provides a flexible platform for fabricating diverse NIR-excitable persistent superclusters.
• The UCZG-SCs and their injectable implant formulation show great promise for advanced photodynamic therapy.
• This approach enables efficient, repetitive phototherapy with enhanced tumor growth inhibition using deep-tissue-penetrating NIR light.