NM07: Nanostructure-Based Optical Bioprobes—Advances, Trends and Challenges in Optical and Multimodular Bioimaging and Sensing
Shangfeng Wang, Fudan University
Ratiometric Imaging of Endogenous Hypochlorous Acid in the Second Near-Infrared Window beyond 1500 nm
Written by Xun Gong
This work reports a fluorescent nanoprobe for the ratiometric detection of reactive oxygen species (ROS) in the second near-infrared window (NIR-II: ∼1000–1700 nm) of lanthanide-based downconversion nanoparticle (NIR-IIb: ~1500-1700 nm). Imaging in NIR-II has many advantages in in vivo imaging including reduced attenuation, tissue scattering, and autofluorescence. The result is higher image quality. To further improve signal, ratiometric sensing is used. By having a built-in control, there is increased signal-to-noise ratio (SNR), decreased photobleaching, and effects of changing particle distributions.
Lanthanides have emission features in the NIR-II window. Downconversion luminescence excited under 808 nm can be effectively quenched by the Cy7.5 chromophores on the surface of nanoparticles through an absorption competition process and subsequently recovered upon the addition of ROS. The downconversion luminescence excited under 980 nm remains unchanged, making a 2 excitation wavelength ratiometric sensor. Optical phantom experiments show no significant signal change within 1-3 mm tissue depths. Finally, LPS injection in mouse studies show lymphnode increase in ROS with SNR of 19.7. This study provides a new design strategies of NIR-II fluorescent probes for precise and reliable measurement in biological systems.