Recent progress of second near-infrared (NIR-II) fluorescence microscopy in bioimaging

Abstract

Visualizing biological tissues in vivo at a cellular or subcellular resolution to explore molecular signaling and cell behaviors is a crucial direction for research into biological processes. In vivo imaging can provide quantitative and dynamic visualization/mapping in biology and immunology. New microscopy techniques combined with near-infrared region fluorophores provide additional avenues for further progress in vivo bioimaging. Based on the development of chemical materials and physical optoelectronics, new NIR-II microscopy techniques are emerging, such as confocal and multiphoton microscopy, light-sheet fluorescence microscopy (LSFM), and wide-field microscopy. In this review, we introduce the characteristics of in vivo imaging using NIR-II fluorescence microscopy. We also cover the recent advances in NIR-II fluorescence microscopy techniques in bioimaging and the potential for overcoming current challenges.

Biological Interaction and Imaging of Ultrasmall Gold Nanoparticles

“…Fluorescence imaging in the NIR-II region shows great potentials in intravital biomedical imaging and analysis, which significantly overcomes the challenges of strong tissue absorption, auto-fluorescence and photon scattering to show deep tissue penetration (up to ~ 3 mm depth), micron-level spatial resolution, and high signal-to-background ratio [ 215 – 217 ]. With the emission redshifts to the NIR-II region from the visible region, the non–radiative transitions from the AuNPs become fast [ 218 – 220 ], resulting in low emission quantum yields (QYs) in the NIR-II region.…”