Surfactant‐Stripped Micelles of Near Infrared Dye and Paclitaxel for Photoacoustic Imaging Guided Photothermal‐Chemotherapy

Development of nanoagents with strong near-infrared (NIR) absorbance and high photothermal conversion capacity is highly desired for efficient photoacoustic (PA) imaging and photothermal therapy of cancers. Herein, surfactant-stripped micelles with photostable near-infrared dye, β-thiophene-fused BF2 -azadipyrromethene (aza-BDTP), are prepared in the presence of paclitaxel (PTX) with Pluronic F127 as the surfactant. Distinct from hydrophobic aza-BDTP and PTX, the obtained surfactant-stripped micelles aza-BDTP/PTX show excellent solubility, physiological stability, and high loading efficiencies for corresponding aza-BDTP and PTX. Intriguingly, these aza-BDTP/PTX micelles exhibit high photothermal conversion efficiency at 33.9%, significantly higher than 16.9% for bare aza-BDTP molecules, owing to aggregation-induced quenching of aza-BDTP fluorescence. With excellent photostability, aza-BDTP/PTX micelles appear to be a highly stable photoacoustic imaging probe and show efficient tumor accumulation as visualized under photoacoustic imaging upon intravenous injection. After being irradiated with a 785 nm laser, 4T1 tumors on the mice with systemic administration of aza-BDTP/PTX micelles are fully eradiated without any recurrences within 60 d. This work presents a general method for efficient encapsulation of hydrophobic aza-BDTP and PTX, obtaining hybrid aza-BDTP/PTX micelles as promising nanotheranostics for imaging guided cancer combination therapy.