Oxygen-Sensitive Quantum Dots for Possible Nanoscale Oxygen Imaging in Cultured Cells
Quantum dots (QDs) are the semiconductor crystal with a nanometer particle size that emit fluorescence of a size-dependent wavelength. In this study, we examined whether l-cysteine-capped CdTe quantum dots (QD580, diameter ~4 nm) might be used as an optical probe for intracellular oxygen (O2) in cultured cells. QD580 was successfully introduced in cultured COS-7 cells by incubating cells with 10 nM QD580 for 5–60 min at 37°C. Cells were exposed to 20 % O2 (0.5 h), then 0.5 % O2 or 20 % O2 (1 h), and finally 20 % O2 (0.5 h) gases. We found significant increases in the fluorescence intensity at 0.5 % O2. However, when compared with QD580 in buffer solution, QD580 fluorescence in cells was considerably weak and vulnerable to repeated excitation light exposures. The present study demonstrated the potential of l-cysteine-capped CdTe QDs as a nanoscale probe for intracellular O2 in cultured cells. Further improvement of the QD is necessary for quantitative assessment of O2 in the cell.
This work was supported by KAKENHI 23500520 to ET.