In Vivo Imaging of Mammalian Embryos by NIR-I Photoacoustic Tomography and NIR-II Optical Coherence Tomography Using Gold Nanostars as Multifunctional Contrast Agents

High quality visualization of live mammalian embryo is an important requirement for studying fetal development. Photoacoustic tomography (PAT) and optical coherence tomography (OCT) are two advanced imaging modalities that have been utilized for embryonic imaging separately. However, high contrast, multiscale, and deep tissue imaging of embryos in vivo remains challenging. Here, we demonstrate multimodal contrast-enhanced imaging of live embryos by gold nanostar-meditated near-infrared I (NIR-I) PAT and near-infrared II (NIR-II) OCT. We investigate intravenous and intravaginal administration of gold nanostars, and significant enhancement of signal, image contrast, and imaging depth are achieved for both PAT and OCT. Our findings may facilitate detailed studies of the morphological and functional changes during embryonic development.