Conjugated Polymer Nanoparticles with Absorption beyond\n1000 nm for NIR-II Fluorescence Imaging System Guided NIR-II Photothermal\nTherapy

Abstract

The second near-infrared\nfluorescence imaging (NIR-II FI) guided\nNIR-II photothermal therapy (PTT) possesses advantages for cancer\ntreatment because of its accurate diagnosis and enhanced therapeutic\neffects for cancer. However, developing a conjugated polymer with\nboth excellent NIR-II fluorescence and NIR-II PTT properties encountered\nmany hindrances, including strong nonradiative decay, low solubility\nin organic solution, and significant aggregation-caused quenching\n(ACQ) effect. Herein, a conjugated polymer TTQ-2TC with optimized\nabsorption in NIR-II regions, good solubility in organic solvents,\nand bright NIR-II FI signals is obtained through introducing the alkyl-side-chain-modified\nbithiophene (2TC) as the electron-rich donor unit. The water-soluble\nnanoparticle (TTQ-2TC NPs) prepared from the conjugated polymer TTQ-2TC\nis used for precise NIR-II FI guided NIR-II PTT treatment. The in\nvivo blood and tumor imaging and therapy results show that the TTQ-2TC\nNPs possess high signal-to-background ratio (SBR) and perfect antitumor\nefficacy by NIR-II PTT.