An Exploration into the Safe and Precise In Vivo Fluorescence Visualization of Uteroplacental Circulation in the NIR-II Window

The uteroplacental circulation is essential for maintaining normal placental physiology and ensuring fetal development. Imaging this circulation is crucial for a comprehensive understanding of its physiological characteristics and associated pathological processes. Fluorescence imaging in the second near-infrared window (NIR-II, 900-1880 nm) offers significant advantages, including high resolution and deep tissue penetration, facilitating more accurate in vivo assessments. In this study, we employed nanoparticles composed of organic fluorescent dyes with NIR-II emission for precise imaging of the uteroplacental circulation. This approach enabled visualization of the uterine artery and placental blood perfusion in pregnant mice with high resolution. We successfully examined the developmental status across different pregnancy stages and assessed pathological alterations associated with inflammation-induced injury. Furthermore, the maternal and fetal safety of the nanoparticles was validated through comprehensive evaluations. These investigations present a novel approach for studying the formation and development of uteroplacental circulation, as well as related pathological conditions.