title: D-glucosamine conjugation accelerates the labeling efficiency of quantum dots in osteoblastic cells.
abstract: Quantum dots (QDs) are useful imaging tools in the medical and biological fields due to their optical properties, such as a high fluorescence intensity, remarkable resistance to photobleaching, broad absorption spectra, and narrow emission spectra. This is the first study to investigate the uptake of carboxylated QDs conjugated with D-glucosamine (core size: approximately 3 nm, final modified size: 20-30 nm) into cultured osteoblastic cells. The QDs attached to the cell surface and were transported into the cytoplasm within approximately three hours of culture, whose process was clearly demonstrated using specific fluorescent staining of the cell membrane. Although the intranuclear distribution was not observed, a dramatic decrease in the transfer of quantum dots into the cytoplasm was recognized after approximately seven days of culture. Other interesting phenomena include the escape of the quantum dots from lysosomes in the cytoplasm, as confirmed by the merging of both QD fluorescence and specific fluorescent staining of lysosomes in the cytoplasm. These findings suggest that D-glucosamine conjugation enhances proton absorption in acid organelles and promotes the lysosomal escape of QDs.
authors.affiliation: Department of Cariology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan.
authors.forename: Kazunari
authors.identifier: 0000-0002-9304-4875
authors.initials: K
authors.lastname: Igawa
authors.affiliation: Biotechnology Division of Care Four Company Ltd., Kokura-Kitaku, Kitakyushu 802-0071, Japan.
authors.forename: Ming-Fang
authors.initials: MF
authors.lastname: Xie
authors.affiliation: Measurement Solution Research Center, National Institute of Advanced Industrial Science and Technology, Tosu, Saga 841-0052, Japan.
authors.forename: Hideki
authors.identifier: 0000-0003-2925-3696
authors.initials: H
authors.lastname: Ohba
authors.affiliation: Department of Cariology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan.
authors.forename: Shizuka
authors.identifier: 0000-0001-5346-5627
authors.initials: S
authors.lastname: Yamada
authors.affiliation: Department of Cariology, Nagasaki University Graduate School of Biomedical Sciences, Nagasaki 852-8588, Japan.
authors.forename: Yoshihiko
authors.identifier: 0000-0002-4256-3085
authors.initials: Y
authors.lastname: Hayashi
mesh_terms: D002460:Cell Line; D005453:Fluorescence; D005944:Glucosamine / Q000378:metabolism*; D006801:Humans; D010006:Osteoblasts / Q000166:cytology / Q000378:metabolism*; D045663:Quantum Dots / Q000378:metabolism*; D013194:Staining and Labeling
chemical_list: D005944:Glucosamine