Excretable Lanthanide Nanoparticle for Biomedical Imaging and Surgical Navigation in the Second Near‐Infrared Window

Recently, various second near‐infrared window (NIR‐II, 1000–1700 nm) fluorophores have been synthesized for in vivo imaging with nonradiation, high resolution, and low autofluorescence. However, most of the NIR‐II fluorophores, especially inorganic nanoprobes, are mainly retained in the reticuloendothelial system (RES) such as the liver and spleen, leading to long‐term safety concerns. Herein, a type of lanthanide‐based excretable NIR‐II nanoparticle, RENPs@Lips, which can be quickly cleared out of body after intravenous administration with half‐lives of 23.0 h for the liver and 14.9 h for the spleen, is reported. Interestingly, over 90% of RENPs@Lips can be excreted through a hepatobiliary system within 72 h postinjection. The moderate blood half‐time (T (1/2) = 17.96 min) allows for multifunctional applications in delineating the hemodynamics of vascular disorders (artery thrombosis, ischemia, and tumor angiogenesis) and monitoring blood perfusion in response to acute ischemia. In addition, RENPs@Lips exhibit high performance in identifying orthotopic tumor vessels intraoperatively and embolization surgery under NIR‐II imaging navigation. Moreover, excellent signal‐to‐background ratio (SBR) is successfully achieved to facilitate sentinel lymph nodes biopsy (SLNB) with tumor‐bearing mice. The high biocompatibility, favorable excretability, and outstanding optical properties warrant RENPs@Lips as novel promising NIR‐II nanoparticles for future applications and translation into an interdisciplinary amalgamation of research in diverse fields.