Interfacial Assembly of Excited-State Engineered Fluorophores on Prussian Blue Particles: A Dual-Targeted Nanoplatform for CO-Augmented Low-Temperature Photothermal Therapy

High-temperature photothermal therapy (PTT) is often hindered by collateral tissue damage and heat shock protein (HSP)-mediated thermo-resistance, necessitating the development of advanced materials for mild-temperature treatments. Herein, we propose an excited-state-engineered donor-dual-acceptor-donor (D-A-A-D) fluorophore that precisely balances radiative and nonradiative decay pathways through a mixed local-excitation/charge-transfer (LE/ICT) state. This molecular design endows the fluorophore with strong fluorescence, efficient photoacoustic (PA) response, and a high photothermal conversion efficiency (η = 42.7%). To enable biological application, we employed an interfacial assembly strategy to integrate this hydrophobic fluorophore with carbonyl-functionalized Prussian Blue (PB) particles, yielding the PB@ATTTO-CO nanoplatform. This hybrid system exhibits dual-organelle (nucleus/mitochondria) targeting. Upon laser irradiation and tumor-microenvironment (TME) stimulation, the nanoplatform triggers controlled CO release, which effectively suppresses HSP70 expression and sensitizes tumor cells to low-temperature hyperthermia. Both in vitro and in vivo studies demonstrate precise FL/PA imaging-guided tumor ablation with minimal systemic toxicity. This work establishes a general principle for integrating excited-state molecular engineering with inorganic colloidal platforms, providing a blueprint for next-generation multimodal phototheranostic materials.