Sn4+‐Mediated Trap Engineering in Cr3+‐Activated Titanate Nanophosphors Enables Self‐Sustained Multimodal Imaging and Combinatorial Oncotherapy

Abstract 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 Gd 3 ⁺‐specific ferromagnetism is highlighted in Na 0.5 Gd 0.5 TiO 3 :Cr 3+ ,Sn 4+ phosphor. By doping with Sn 4+ , 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 0.5 Gd 0.5 TiO 3 :Cr 3+ ,Sn 4+ with sub 100 nm dimensions are synthesized by coprecipitation. Following SiO 2 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 SiO 2 , achieving ≈50% bactericidal and antitumour effects, endowing the system with integrated antibacterial‐antitumour efficacy, thereby establishing a multifunctional capability for simultaneous diagnosis and therapy.