Figure 2.

Comparison of NMR spectra for each F-PA as a function of peptide concentration: 1.0 mM (blue), 1.5 mM (green), 2.0 mM (orange) and 3.0 mM (red). C₇E₂ and C₇K₃ maintain sharp peaks at the higher concentrations needed to obtain ¹⁹F MR images. The other conjugates exhibited sharp spectral features only at concentrations lower than 2 mM or always exhibited broad features. Measurements conducted at pH 6.5.