Fig. 7
The labeling efficiency of different concentrations of QDs on MSCs. Different amounts of QDs (100 μg/ml) (5, 10, 15, and 20 μl/ml) were incubated with MSCs for 4 h to determine the optimal labeling efficiency. Bright-field images (left, a, c, e, g) and fluorescence images (right, b, d, f, h) were taken under inverted fluorescence microscope. Circle 1 and circle 2 indicated the same cell image in bright-field and fluorescence background. The remaining circle 3 and circle 4, circle 5 and circle 6, and circle 7 and circle 8 were respectively the same single-cell image under bright-field images (left) and fluorescence images (right)