A highly water-soluble triblock conjugated polymer for in vivo NIR-II imaging and photothermal therapy of cancer

• Published in: Polymer chemistry 2018-06, Vol.9 (22), p.3118-3126
• Main Authors: Lu, Xiaomei, Yuan, Pengcheng, Zhang, Wansu, Wu, Qi, Wang, Xiaoxiao, Zhao, Meng, Sun, Pengfei, Huang, Wei, Fan, Quli
• Format: Article
• Language: English
• Subjects: Biopolymers; Emission; Fluorescence; Imaging; Infrared windows; Photothermal conversion; Polymer chemistry; Polymers; Reagents; Solubility; Therapy; Tumors; Water chemistry; Water soluble polymers
• ISSN: 1759-9954; 1759-9962
• DOI: 10.1039/C8PY00215K

Applications of the second near infrared (NIR) optical window (NIR-II, 1000–1700 nm) have received increasing attention with respect to reduced scattering and negligible auto-fluorescence, thus achieving a high signal-to-background ratio for pinpointing tumors compared with NIR-I imaging. Conjugated polymers have been applied in NIR-II imaging for their advantages, such as high molar extinction coefficient, wide emission wavelength, and ease of preparation. However, currently available conjugated polymer NIR-II agents suffer from a lack of water solubility. Hence, a highly water-soluble triblock conjugated polymer (POEGMA- b -PDPP- b -POEGMA) based on diketopyrrolopyrrole was successfully prepared with a high yield. The NIR-II imaging depth of the conjugated polymer was ∼7 mm, which is far beyond conventional NIR-I agents. Furthermore, the fluorescence quantum yield (QY) of POEGMA- b -PDPP- b -POEGMA reached up to 1.0%, which is higher than most reported NIR-II probes. This novel NIR-II conjugated polymer shows improved solubility (>10 mg mL −1 ) and greater dispersion in aqueous solution compared to those conventional conjugated polymers, due to the introduction of the water-soluble polymer POEGMA. With the help of high emission (>1000 nm), POEGMA- b -PDPP- b -POEGMA could efficiently realize the highly penetrable NIR-II imaging of tumors. In addition, POEGMA- b -PDPP- b -POEGMA could be a promising photothermal therapy agent to ablate tumors due to its high photothermal conversion efficiency (52%).