High Spatial and Temporal Resolution NIR-IIb Gastrointestinal Imaging in Mice

Abstract

Conventional biomedical imaging modalities, including endoscopy, X-rays, and magnetic resonance, are invasive and cannot provide sufficient spatial and temporal resolutions for regular imaging of gastrointestinal (GI) tract to guide prognosis and therapy of GI diseases.Here we report a non-invasive method for optical imaging of GI tract. It is based on a new type of lanthanide-doped nanocrystal with near-infrared (NIR) excitation at 980 nm and second NIR window (NIR-IIb) (1500~1700 nm) fluorescence emission at around 1530 nm. The rational design and controlled synthesis of nanocrystals with high brightness have led to an absolute quantum yield (QY) up to 48.6%. Further benefitting from the minimized scattering through the NIR-IIb window, we enhanced the spatial resolution by 3 times compared with the other NIR-IIa (1000~1500 nm) contract agents for GI tract imaging. The approach also led to a high temporal resolution of 8 frames per second, so that the moment of mice intestinal peristalsis happened in one minute can be captured. Furthermore, with a light-sheet imaging system, we demonstrated a three-dimensional (3D) imaging of the stereoscopic structure of the GI tract.Moreover, we successfully translate these advances to diagnose inflammatory bowel disease (IBD) in a pre-clinical model of mice colitis.

Nanocrystals for Deep-Tissue In Vivo Luminescence Imaging in the Near-Infrared Region

“…315 To achieve high spatial and temporal resolutions for noninvasive NIR-IIb imaging of the gastrointestinal tract and diagnose gastrointestinal diseases, Mi et al developed gum arabic (GA) coated core−shell nanocrystals, NaYbF 4 : Er 3+ ,Ce 3+ ,Zn 2+ @CaF 2 (ErNCs@GA), which exhibited strong NIR-IIb emission peak at approximately 1530 nm (Figure 27a). 316 By employing ErNCs@GA nanocrystals as a contrast agent, robust NIR-IIb fluorescent signals were observed in the stomach of mice, gradually progressing to the intestine (Figure 27b). This approach allowed precise delineation of intestine, rectum, and colon, with improved spatial resolution, facilitating the monitoring of gastrointestinal motions and meal transit within the intestinal tract.…”

Tailored NIR‐II Lanthanide Luminescent Nanocrystals for Improved Biomedical Application

“…[ 96 ] In 2022, Mi and colleagues further heightened the absolute QY to 48.6% from NaYF 4 :2%Er/2%Ce/10%Zn@CaF 2 nano‐powders with large particles size (80.9 nm). [ 97 ] However, hydroxyl group with stretching vibration frequencies ≈3000 cm −1 has a serious quenching effect on 1550 nm emission (6500 cm −1 ) of Er 3+ through a two‐phonon quenching mechanism. Moreover, water absorption ≈at 1500 nm also aggravates the intensity decline of Er 3+ emission.…”

Tracking of Intestinal Probiotics In Vivo by NIR-IIb Fluorescence Imaging

“…The second near-infrared window (NIR-II), 1000–1700 nm wavelength offers excellent tissue penetration capabilities and high resolution. − Use of the NIR-II spectrum has been successfully applied for vasculature, skeleton, and tumor imaging . In particular, the NIR-IIb window (1500–1700 nm) has been found to further improve the quality of tissue imaging applications with minimal photon scattering and higher signal-to-background ratios (SBRs). − In recent years, NIR-IIb small-molecule probes and nanoprobes have proven to be of great use for in vivo imaging and diagnostics. ,, Compared with small-molecule probes, some nanoprobes have higher metabolic and chemical stability. , However, introduced into the blood, nanomaterials tend to accumulate in the liver and kidney, thus inducing toxicity, which poses a significant limitation for tumor or vascular imaging. − …”