Enabling Prussian Blue with Tunable Localized Surface Plasmon Resonances: Simultaneously Enhanced Dual-Mode Imaging and Tumor Photothermal Therapy.

Prussian blue (PB) has been used as a photothermal conversion agent to generate heat to induce localized damage to tumor. However, its therapeutic efficiency is far from satisfactory. One of the major obstacles is that the maximum NIR absorption peak of PB within 690-720 nm cannot be optimized near the wavelength of the laser to enhance its therapeutic efficiency. Herein, we report that the integration of Gd into PB nanocrystals (GPB NCs) enables PB with tunable localized surface plasmon resonances (LSPRs) from 710 to 910 nm, achieving the maximum NIR peak near the wavelength of the laser. Concurrently, the efficiency of dual-mode imaging including photoacoustic imaging and magnetic resonance imaging has been greatly improved. These enhancements in dual-mode imaging and photothermal therapy enable PB with low nanomaterial dose and laser flux. Additionally, it is found that GPB NCs show the capability of not only acting as a chemical probe with tunable sensitivity but also scavenging reactive oxygen species. The integration of functional ions into a photothermal conversion agent is an efficient strategy to improve the synergy of nanoagent, enchancing tumor theranostic efficiency.