Near-Infrared Photoluminescent Carbon Nanotubes for Imaging of Brown Fat.
Near-infrared photoluminescent single-walled carbon nanotubes (CNTs) are expected to provide effectual bio-imaging tools, although, as yet, only limited applications have been reported. Here, we report that CNTs coated with an amphiphilic and biocompatible polymer, poly(2-methacryloyloxyethyl phosphorylcholine-co-n-butyl methacrylate; PMB), generate high-quality images of brown fat. Brown fat is a heat-productive adipose tissue, which is attracting increasing attention as a new therapeutic target for obesity-associated metabolic disorders. Its brown colour is mainly attributed to densely packed capillaries, which facilitate its high heat-exchanging efficiency. Currently, positron emission tomography-computed tomography is the only practical technique to identify brown fat distribution in the living body; however, it is expensive to use. By virtue of their high affinity to apolipoproteins and exemption from macrophage phagocytosis, PMB-CNTs selectively accumulate on capillary endothelial cells but not larger vessels in adipose tissue. Therefore, the image brightness of adipose tissue can directly reflect the capillary density, and indirectly the thermogenic capability and brownness. PMB-CNTs provide clearer images than conventional organic dyes, as the high level of transmitted light passes through the body with less light scattering. Thus, PMB-CNT-based imaging methods could open a new phase in thermogenic adipose tissue research.
Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8565, Japan.
Masako
M
Yudasaka
Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8565, Japan.
Yohei
Y
Yomogida
CNT-Application Research Center, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8565, Japan.
Minfang
M
Zhang
Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8565, Japan.
Takeshi
T
Tanaka
Department of Disease Control, Research Institute, National, Center for Global Health and Medicine, Shinjuku-ku, Tokyo 162-8655, Japan.
Masako
M
Nakahara
Department of Disease Control, Research Institute, National, Center for Global Health and Medicine, Shinjuku-ku, Tokyo 162-8655, Japan.
Norihiko
N
Kobayashi
Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan.
Yuko
Y
Okamatsu-Ogura
Department of Biomedical Sciences, Graduate School of Veterinary Medicine, Hokkaido University, Sapporo, 060-0818, Japan.
Ken
K
Machida
Department of Materials Engineering, The University of Tokyo, Hongo, Tokyo 113-8656, Japan.
Kazuhiko
K
Ishihara
Department of Disease Control, Research Institute, National, Center for Global Health and Medicine, Shinjuku-ku, Tokyo 162-8655, Japan.
Kumiko
K
Saeki
Nanomaterials Research Institute, National Institute of Advanced Industrial Science and Technology, Tsukuba, Ibaraki 305-8565, Japan.
Hiromichi
H
Kataura
D002001:Adipose Tissue, Brown / Q000033:anatomy & histology* / Q000166:cytology / Q000648:ultrastructure; D052436:Adipose Tissue, White / Q000648:ultrastructure; D000818:Animals; D001053:Apolipoproteins / Q000378:metabolism; D042783:Endothelial Cells / Q000166:cytology; D021621:Imaging, Three-Dimensional; D008163:Luminescent Measurements / Q000379:methods*; D008689:Methacrylates / Q000737:chemistry; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D037742:Nanotubes, Carbon / Q000737:chemistry* / Q000648:ultrastructure; D010767:Phosphorylcholine / Q000031:analogs & derivatives / Q000737:chemistry; D019265:Spectroscopy, Near-Infrared
D001053:Apolipoproteins; D008689:Methacrylates; D037742:Nanotubes, Carbon; D010767:Phosphorylcholine; C070638:2-methacryloyloxyethyl phosphorylcholine