High-precision detection and navigation surgery of colorectal cancer micrometastases.

Surgical resection is an effective treatment for colorectal cancer (CRC) patients, whereas occult metastases hinder the curative effect. Currently, there is no effective method to achieve intraoperatively diagnosis of tumor-positive lymph nodes (LNs). Herein, we adopt a near-infrared-II (NIR-II) organic donor-pi-acceptor-pi-donor probe FE-2PEG, which exhibits bright fluorescence over 1100 nm, excellent photostability, blood circulation time, and biocompatibility, to achieve high-performance bioimaging with improved temporal and spatial resolution. Importantly, the FE-2PEG shows efficient passive enrichment in orthotopic CRC, metastatic mesenteric LNs, and peritoneal metastases by enhanced permeability and retention effect. Under NIR-II fluorescence-guided surgery (FGS), the peritoneal micrometastases were resected with a sensitivity of 94.51%, specificity of 86.59%, positive predictive value (PPV) of 96.57%, and negative predictive value of 79.78%. The PPV still achieves 96.07% even for micrometastases less than 3 mm. Pathological staining and NIR-II microscopy imaging proved that FE-2PEG could successfully delineate the boundary between the tumor and normal tissues. Dual-color NIR-II imaging strategy with FE-2PEG (1100 ~ 1300 nm) and PbS@CdS quantum dots (> 1500 nm) successfully protects both blood supply and normal tissues during surgery. The NIR-II-based FGS provides a promising prospect for precise intraoperative diagnosis and minimally invasive surgery of CRC.

Recent Advances of Organic Near-Infrared II Fluorophores in Optical Properties and Imaging Functions.

Near-infrared (NIR) fluorescence imaging (FI) has become a research hotspot because of its distinctive imaging properties: high temporal resolution and sensitivity. Especially in recent years, with the research focus of NIR FI shifting to the NIR-II region, which has better imaging performance, it is expected that NIR FI will find significant applications in the field of in vivo imaging. One of the most crucial directions for research into NIR-II FI is the promotion of novel NIR-II fluorophores with superior imaging properties. The remarkable advantages of organic NIR-II fluorophores in biosafety make them more promising than other fluorescent materials in certain applications. But serious defects in their fluorescence performance preclude particular imaging effects and limit imaging functions. In this review, we summarize and discuss the recent leading literature on overcoming the defects of organic NIR-II fluorophores, demonstrating the potential for further improving their imaging properties. In addition, we cover the functions of NIR-II FI that are promoted by the development of fluorophores, notably including its outlook on molecular imaging in vivo.