Tannic Acid–Based\nSelf-Assembling Nanocarriers\nwith Antiphotobleaching and Controlled Releasing Properties for Collaborative\nNear-Infrared Photothermal/Photodynamic Therapy

Near-infrared (NIR) organic materials have been widely\ndeveloped\nfor tumor phototherapy due to their deep tumor penetration, good biodegradability,\nand high photothermal conversion (PCE). However, most of the NIR organic\ndyes are easily destroyed by photooxidation due to their big and long\nconjugated structures, such as cyanine dyes. Under light irradiation,\nthe reactive oxygen species (ROS) produced by these NIR dyes can easily\nbreak their conjugated skeleton, resulting in a dramatic decrease\nin phototherapeutic efficiency. Herein, an NIR organic dye cyanine\ndye (CyS) and a photosensitizer methylene blue (MB) were chosen to\nprepare nanocarrier CMTNPs by facile self-assembling with a natural\nantioxidant, tannic acid (TA). TA can greatly enhance the stability\nof NIR cyanine dyes by scavenging ROS. Furthermore, CMTNPs have a\ncharacter of pH/thermal dual response, allowing for controlled release\nof MB in the slightly acidic tumor environment during photothermal\ntherapy. The released MB can turn on both fluorescence and photodynamic\ntherapy effects. In vitro and in vivo experiments demonstrated the\nremarkable tumor ablation ability of CMTNPs. Thus, our study provided\nan antiphotobleaching and controlled release photosensitizer strategy\nthrough the introduction of antioxidant TA into the nanocarrier for\nefficient collaborative photothermal/photodynamic therapy.