BODIPY-Based Photothermal Agent Incorporating Azulene for Enhanced NIR Absorption and Tumor Ablation

Photothermal therapy (PTT) is a promising minimally invasive treatment that converts light energy into localized heat for tumor ablation. Indocyanine green (ICG), the only clinically approved photothermal agent (PTA), suffers from rapid photobleaching and poor tumor retention, underscoring the urgent need for next-generation PTAs with improved properties. In this study, we report AzuGlu-BODIPY, a novel azulene-containing BODIPY-based PTA incorporating 1,2,3,4-tetrahydroquinoline and glucose, designed to overcome these limitations. AzuGlu-BODIPY demonstrates a high photothermal conversion efficiency (PCE) of 51%, effective near-infrared (NIR) absorption, and thermal stability in both dimethyl sulfoxide (DMSO) and aqueous solutions. In vitro studies revealed potent photothermal efficacy against cancer cell lines, with IC₅₀ values of 3.1-4.6 μM under 808 nm laser irradiation, while in vivo experiments showed complete tumor regression in 4T1 tumor-bearing mice following localized administration and laser treatment. These results suggest AzuGlu-BODIPY as a promising PTA and provide a versatile platform for advancing azulene-based PTAs with enhanced functionality for PTT.