Rational synthesis of IR820–albumin complex for NIR-II fluorescence imaging-guided surgical treatment of tumors and gastrointestinal obstruction

IR820, an analog of FDA-approved indocyanine green, is a promising second near-infrared window (NIR-II) fluorescence probe with better NIR-II fluorescence stability and great clinical transformation potential. Moreover, its fluorescence can be further remarkably enhanced by the interaction with albumin. Therefore, it is significant to flexibly design IR820–albumin complex using endogenous or exogenetic albumin to meet the requirements of different biological applications. Herein, we show the rational synthesis of IR820–albumin complex for NIR-II fluorescence imaging-guided surgical treatment of tumors and gastrointestinal obstruction. We compared the NIR-II fluorescence imaging ability of IR820 pre-incubated with albumin or not to visualize tumors and the gastrointestinal tract in vivo and found that the formation of IR820–albumin was essential for the intense NIR-II fluorescence. For imaging-guided tumor treatment, after intravenous injection of free IR820, IR820–albumin complex can be formed in vivo due to the presence of plenty of albumin in the blood. For imaging-guided gastrointestinal obstruction removal, IR820–albumin complex should be synthesized in vitro before oral administration. NIR-II fluorescence imaging-guided surgeries were successfully realized in both tumor resection and gastrointestinal obstruction removal. Besides, toxicity assessments in vitro and in vivo confirmed the good biocompatibility of IR820. Our study provides a flexible paradigm for IR820-based NIR-II fluorescence imaging and surgical navigation towards different diseases.