Leveraging Coupling Effect‐Enhanced Surface Plasmon Resonance of Ruthenium Nanocrystal‐Decorated Mesoporous Silica Nanoparticles for Boosted Photothermal Immunotherapy

Abstract Photothermal immunotherapy (PTI) has emerged as a promising approach for cancer treatment, while its efficacy is often hindered by the immunosuppressive tumor microenvironment (TME). Here, this work presents a multifunctional platform for tumor PTI based on ruthenium nanocrystal‐decorated mesoporous silica nanoparticles (RuNC‐MSN). By precisely regulating the distance between RuNC on MSN, this work achieves a remarkable enhancement in surface plasmon resonance of RuNC, leading to a significant improvement in the photothermal efficiency of RuNC‐MSN. Furthermore, the inherent catalase‐like activity of RuNC‐MSN enables effective modulation of the immunosuppressive TME, thereby facilitating an enhanced immune response triggered by the photothermal effect‐mediated immunogenic cell death (ICD). As a result, RuNC‐MSN exhibits superior PTI performance, resulting in pronounced inhibition of primary tumor and metastasis. This study highlights the rational design of PTI agents with coupling effect‐enhanced surface plasmon resonance, enabling simultaneous induction of ICD and regulation of the immunosuppressive TME, thereby significantly boosting PTI efficacy.