Conjugated Polymer Coupled with Nonconjugated Segments\nfor NIR-II Fluorescence/NIR-II Photoacoustic Imaging-Guided NIR-II\nPhotothermal Therapy

Abstract

Development\nof conjugated polymer-based water-soluble nanoparticles\n(NPs) for second near-infrared fluorescence (NIR-II FL, 1000–1700\nnm) and NIR-II photoacoustic (PA) imaging-guided NIR-II photothermal\ntherapy (PTT) is expected to gain favor in clinical anticancer applications.\nHowever, integrating these imaging and therapeutic functions into\na single NIR-II absorption conjugated polymer BTC12 is a major challenge\nto accurately balance the nonradiative and radiative decay pathways.\nHerein, an NIR-II absorption conjugated polymer was designed and synthesized\nby coupling flexible nonconjugated segments into a polymer backbone\nto simultaneously achieve NIR-II FL, NIR-II PA imaging, and NIR-II\nPTT. The developed conjugated polymer-based water-soluble NPs (BTC12\nNPs) showed satisfactory functionality with a promising photothermal\nconversion efficiency of 46.8%. An in vivo study demonstrated that\nBTC12 NPs can accurately acquire the tumor location and size via NIR-II\nFL/NIR-II PA imaging. Furthermore, BTC12 NPs showed marked antitumor\nefficacy by NIR-II PTT upon 1064 nm laser irradiation. This work provides\na perspective for the design of multifunction conjugated polymers\nfor NIR-II FL/NIR-II PA imaging-guided NIR-II PTT applications.