{Reference Type}: Journal Article {Title}: Biological imaging without autofluorescence in the second near-infrared region {Author}: Diao, Shuo; Hong, Guosong; Antaris, Alexander L.; Blackburn, Jeffrey L.; Cheng, Kai; Cheng, Zhen; Hongjie, Dai {Journal}: Nano Research {ISBN/ISSN}: 1998-0124 {Year}: 2015 {Volume}: 8 {Issue}: 9 {Pages}: 3027-3034 {DOI}: 10.1007/s12274-015-0808-9 {Keywords}: fluorescence imaging {Keywords}: nanotechnology {Keywords}: autofluorescence {Keywords}: second near-infrared {Abstract}: Fluorescence imaging is capable of acquiring anatomical and functional information with high spatial and temporal resolution. This imaging technique has been indispensable in biological research and disease detection/diagnosis. Imaging in the visible and to a lesser degree, in the near-infrared (NIR) regions below 900 nm, suffers from autofluorescence arising from endogenous fluorescent molecules in biological tissues. This autofluorescence interferes with fluorescent molecules of interest, causing a high background and low detection sensitivity. Here, we report that fluorescence imaging in the 1, 500–1, 700-nm region (termed "NIR-Ⅱb") under 808-nm excitation results in nearly zero tissue autofluorescence, allowing for background-free imaging of fluorescent species in otherwise notoriously autofluorescent biological tissues, including liver. Imaging of the intrinsic fluorescence of individual fluorophores, such as a single carbon nanotube, can be readily achieved with high sensitivity and without autofluorescence background in mouse liver within the 1, 500–1, 700-nm wavelength region. {URL}: https://www.sciopen.com/article/10.1007/s12274-015-0808-9 {Language}: en