Preparation and characterization of highly fluorescent, glutathione-coated near infrared quantum dots for in vivo fluorescence imaging.
Fluorescent probes that emit in the near-infrared (NIR, 700-1,300 nm) region are suitable as optical contrast agents for in vivo fluorescence imaging because of low scattering and absorption of the NIR light in tissues. Recently, NIR quantum dots (QDs) have become a new class of fluorescent materials that can be used for in vivo imaging. Compared with traditional organic fluorescent dyes, QDs have several unique advantages such as size- and composition-tunable emission, high brightness, narrow emission bands, large Stokes shifts, and high resistance to photobleaching. In this paper, we report a facile method for the preparation of highly fluorescent, water-soluble glutathione (GSH)-coated NIR QDs for in vivo imaging. GSH-coated NIR QDs (GSH-QDs) were prepared by surface modification of hydrophobic CdSeTe/CdS (core/shell) QDs. The hydrophobic surface of the CdSeTe/CdS QDs was exchanged with GSH in tetrahydrofuran-water. The resulting GSH-QDs were monodisperse particles and stable in PBS (phosphate buffered saline, pH = 7.4). The GSH-QDs (800 nm emission) were highly fluorescent in aqueous solutions (quantum yield = 22% in PBS buffer), and their hydrodynamic diameter was less than 10 nm, which is comparable to the size of proteins. The cellular uptake and viability for the GSH-QDs were examined using HeLa and HEK 293 cells. When the cells were incubated with aqueous solutions of the GSH-QDs (10 nM), the QDs were taken into the cells and distributed in the perinuclear region of both cells. After 12 hrs incubation of 4 nM of GSH-QDs, the viabilities of HeLa and HEK 293 cells were ca. 80 and 50%, respectively. As a biomedical utility of the GSH-QDs, in vivo NIR-fluorescence imaging of a lymph node in a mouse is presented.
Jin
Takashi
T
WPI Immunology Frontier Research Center, Osaka University, Suita 565-0871, Osaka, Japan.|Graduate School of Frontier Biosciences, High Performance Bioimaging Facility, Osaka University, Suita 565-0871, Osaka, Japan.
Fujii
Fumihiko
F
WPI Immunology Frontier Research Center, Osaka University, Suita 565-0871, Osaka, Japan.
Komai
Yutaka
Y
WPI Immunology Frontier Research Center, Osaka University, Suita 565-0871, Osaka, Japan.
Seki
Junji
J
WPI Immunology Frontier Research Center, Osaka University, Suita 565-0871, Osaka, Japan.|National Cardiovascular Center Research Institute, Suita 565-8561, Osaka, Japan.
Seiyama
Akitoshi
A
Graduate School of Medicine, Kyoto University, Kyoto 606-8507, Japan.
Yoshioka
Yoshichika
Y
WPI Immunology Frontier Research Center, Osaka University, Suita 565-0871, Osaka, Japan.|Graduate School of Frontier Biosciences, High Performance Bioimaging Facility, Osaka University, Suita 565-0871, Osaka, Japan.