Figure 6.
The dependence of CEST on concentration. (A) The percentage CEST effects of the amide (solid circles) and amine (open circles) of Yb– DO3A–oAA were measured at pH 7.20 and 37°C using 10 µT saturation power over a range of concentrations. The curved lines were calculated from the Hanes-like analysis shown in (B) [see (39) for details]. The ratio of the CEST effects (diamonds) was fitted with a linear function to demonstrate that the ratio is independent of concentration. (B) The high R2 correlation coefficients of the linear fit of the Hanes-like analysis method to the experimental data indicated that the chemical exchange of the amide (solid circles) or amine (open circles) with water can be approximated as a two-pool model. (C) The pH values measured from the CEST effects of Yb–DO3A–oAA were independent of concentration. The dashed line represents the pH measured with an electrode.