Ultrafine fiber-mediated transvascular interventional photothermal therapy using indocyanine green for precision embolization treatment

Photothermal treatment has attracted immense interest as a promising approach for biomedical applications such as cancer ablation, yet its effectiveness is often limited by insufficient laser penetration and challenges in achieving efficient targeting of photothermal agents. Here we developed a transvascular interventional photothermal therapy (Ti-PTT), which employed a small-sized microcatheter (outer diameter: 0.60 mm, 1.8 Fr) equipped with an ultrafine optical fiber (diameter: 100 μm) capable of simultaneously delivering photothermal agents while performing 808 nm laser irradiation <i>via</i> an endovascular route. Specifically, we employed two types of indocyanine green (ICG)-based photothermal agents, <i>i.e.</i> ICG solution serving as a purely photothermal agent and ICG-ethiodized oil (ICG-EO) emulsion acting as a radiopaque photothermal embolic agent. Using the customized microcatheter with the ICG solution, both proximal and distal embolization were able to be performed in a rat liver model. Compared to the ICG solution, the ICG-EO emulsion dramatically enhanced the ICG retention time, enabling a photothermally triggered precision vascular blockade to induce local embolization of large tissue volumes in a rat kidney model with an unfavorable ICG leakage rate. The Ti-PTT paves the way to broadening the potential applications of photothermal therapy through combination with clinical intervention-based approaches.