Generating New Cross-Relaxation Pathways by Coating Prussian Blue on NaNdF₄ To Fabricate Enhanced Photothermal Agents

Cross-relaxation among sensitizers is commonly regarded as deleterious in fluorescent materials, although favorable in photothermal agents. Herein, we coated Prussian blue (PB) on NaNdF₄ nanoparticles to fabricate core–shell nanocomplexes with new cross relaxation pathways between the ladder-like energy levels of Nd³⁺ ions and continuous energy band of PB. The photothermal conversion efficiency was improved exceptionally and the mechanism of the enhanced photothermal effect was investigated. In vivo photoacoustic imaging and photothermal therapy demonstrated the potential of the enhanced photothermal agents. Moreover, the concept of generating new cross-relaxation pathways between different materials is proposed to contribute to the design of all kinds of enhanced photothermal agents.