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

Abstract

The ability to accurately characterize microorganism distribution in the intestinal tract is helpful for understanding intrinsic mechanisms. Within the intestine, traditional optical probes used for microorganism labeling commonly suffer from a low imaging penetration depth and poor resolution. We report a novel observation tool useful for microbial research by labeling near-infrared-IIb (NIR-IIb, 1500−1700 nm) lanthanide nanomaterials NaGdF 4 :Yb 3+ ,Er 3+ @NaGdF 4 ,Nd 3+ (Er@Nd NPs) onto the surface of Lactobacillus bulgaricus (L. bulgaricus) via EDC-NHS chemistry. We monitor microorganisms in tissue by two-photon excitation (TPE) microscopy and in vivo with NIR-IIb imaging. This dual-technique approach offers great potential for determining the distribution of transplanted bacteria in the intestinal tract with a higher spatiotemporal resolution.

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

“…Copyright 2017 under the terms of the Creative Commons Attribution License (). (d–g) Adapted with permission from ref . Copyright 2019 American Chemical Society.…”

“…Polyethylenimine (PEI)-modified nanoparticles (NP@PEI) were attached to the surface of Lactobacillus bulgaricus (L.b) using the EDC-NHS activation system (Figure 28d). 323 Under 808 nm excitation, the integrated system of Er@Nd nanoparticles with L.b (L.b-NPs) accurately imaged mouse intestinal tissue. The imaging modality exhibited exceptional spatiotemporal resolution with a SBRs of 6.88 and a narrow fwhm of 2.653 mm.…”

“…Therefore, Ji et al engineered a NIR-II fluorescent probe by covalent labeling between microbiota and lanthanide nanocrystals (NaGdF 4 :​Yb 3+ ,Er 3+ @NaGdF 4 ,Nd 3+ ) for tracking intestinal probiotics (Figure d–g). Polyethylenimine (PEI)-modified nanoparticles (NP@PEI) were attached to the surface of Lactobacillus bulgaricus (L.b) using the EDC-NHS activation system (Figure d) . Under 808 nm excitation, the integrated system of Er@Nd nanoparticles with L.b (L.b-NPs) accurately imaged mouse intestinal tissue.…”

“…Moreover, it demonstrated remarkable tissue penetration capabilities, allowing visualization up to approximately 7 mm in depth. By capturing the NIR-IIb signals, the presence of L.b labeled with Er@Nd NPs could be visualized within the mouse intestines, and it was observed that the bacteria had reached the small intestine within 30 min (Figure e–g) . Besides, NIR fluorescence imaging combined with others imaging mode holds significant promise in achieving high sensitivity and temporal resolution for accurate detection of gastrointestinal disorders.…”

Ultrabright NIR-IIb Fluorescence Quantum Dots for Targeted Imaging-Guided Surgery

“…Particularly, NIR-IIb (1500–1700 nm) fluorescence bioimaging offers a lengthy spectral wavelength region characterized by low light scattering and minimal autofluorescence. This unique feature enables NIR-IIb fluorescence bioimaging to acquire accurate local submicroscopic fluorescence images, providing comprehensive information about small lesions even at significant depths within organisms …”