In Vitro and In Vivo Near‐Infrared Photothermal Therapy of Cancer Using Polypyrrole Organic Nanoparticles

Kai Yang , Huan Xu , Liang Cheng , Chunyang Sun , Jun Wang , and Zhuang Liu * IO N Photothermal therapy (PTT) that uses optical absorbing agents to “cook” cancer under light irradiation has attracted signifi cant attention in recent years as a promising alternative or supplement to traditional cancer therapies. [ 1–3 ] Numerous reports have shown encouraging therapeutic effects of PTT in many preclinical animal experiments, using various light absorbing nanomaterials as PTT agents. [ 1–21 ] Ideal PTT agents should exhibit strong absorbance in the near-infrared (NIR) region, which is a transparency window for biological tissues, and could effi ciently transfer the absorbed NIR optical energy into heat. The biocompatibility of PTT agents is another primary concern. The tumor-homing ability of PTT agents is also important for photothermal treatment of cancer upon systemic administration. Gold nanomaterials including nanorods, nanocages, nanoshells, and composite nanostructures are likely the mostwidely explored class of PTT nanoagents. [ 4–8 , 19 , 20 ] A number of other inorganic nanomaterials, such as carbon nanomaterials [ 9–13 , 17 , 18 , 21 ] (e.g., carbon nanotubes, nanographene), Pd nanosheets, copper sulfi de and copper selenide nanoparticles, have also shown potential in PTT cancer treatment. [ 14–16 ] However, the majority of currently used PTT agents are inorganic nanomaterials, which usually are not biodegradable and may remain inside the body for long periods of time after systemic administration. The use of organic nanoparticles, such as porphysome and light-absorbing conductive polymers, as PTT agents, has thus attracted signifi cant attention recently. [ 22–24 ]