Sn ⁴⁺ ‐Mediated Trap Engineering in Cr ³⁺ ‐Activated Titanate Nanophosphors Enables Self‐Sustained Multimodal Imaging and Combinatorial Oncotherapy

Multimodal imaging provides comprehensive and precise tools that significantly increase the efficiency and accuracy in clinical decision-making. The integration of superior multimodal imaging capabilities with stimuli-responsive drug release functionalities within a single nanoplatform holds crucial promise for both scientific exploration and clinical translation but remains a formidable challenge in advancing precision medicine. The unique integration of near-infrared emission (λ_em = 760 nm), multiwavelength-rechargeable afterglow, photostimulated luminescence under 980 nm excitation, and Gd³⁺-specific ferromagnetism is highlighted in Na_0.5Gd_0.5TiO₃:Cr³⁺,Sn⁴⁺ phosphor. By doping with Sn⁴⁺, a threefold enhancement in the luminescent performance is achieved, demonstrating a 1.37-fold increase in initial afterglow brightness and extending the persistent luminescence duration to over 15 h. Uniform cubic long-persistent luminescent nano-phosphor Na_0.5Gd_0.5TiO₃:Cr³⁺,Sn⁴⁺ with sub 100 nm dimensions are synthesized by coprecipitation. Following SiO₂ surface functionalization, it showed sustained luminescence exceeding 2.5 h under UV charging, as validated by in vivo murine imaging. Notably, ≈2 h of imaging can still be achieved in mice under blue light charging. A theragnostics nanoplatform is developed by conjugating drugs onto the exterior of SiO₂, achieving ≈50% bactericidal and antitumour effects, endowing the system with integrated antibacterial-antitumour efficacy, thereby establishing a multifunctional capability for simultaneous diagnosis and therapy.