19F MR Characterization of Fluorinated Proteins and Relaxation Rate Enhancement with Gd-DTPA for Faster Imaging

6-Fluoropyridoxal Polymer Conjugates: Novel 19F pH Indicators for Magnetic Resonance Spectroscopy

“…The change in 19 F chemical shift in vitamin B 6 analog (1) with pH is mainly due to the protonation/deprotonation of the 3-position hydroxy group, which influences the electronic environment around fluorine at the 6-position (the effect being more pronounced due to the para location). Assuming that this structure sensitivity relationship holds, the remaining three positions (2, 4, and 5) in the pyridoxine ring could be exploited for conjugation to polymers without sacrificing the pH sensing capability of the pH indicator.…”

“…19 F chemical shift of 6-FPAL (2, 4) and 6-FPALpolymer conjugate (4, 9) vs pH in water. The pKa for conjugate is shifted toward the physiological range.…”

“…Besides pH mapping, an immediate extension of the methodology will be to develop other 19 F physiological markers, e.g., pO 2 , temperature, redox state, cation concentration, and perfusion using 19 6 Reaction of Conjugate (5) with S-ethyl trifluorothioacetate. 5 was dissolved in 0.1 M NaHCO 3 followed by S-ethyl trifluorothioacetate addition (5 M excess), while maintaining the pH at ∼8.0.…”

“…The solution was lyophilized to yield TFA-[6-FPAL-albumin] conjugate (7). 19 F NMR spectrum of 6-FPAL-polylysine (4) together with 6-FPOL (1) in whole blood (pH 7.36) with CF3-COONa as an external reference. Conjugate 4 shows a single resonance (δ -17.89) corresponding to extracellular pH (7.4), while 6-FPOL (1) shows two signals (δ -10.7 and -11.4) representing the pH from intracellular (pH 7.18) and extracellular (pH 7.48) compartments.…”

“…19 F chemical shift titration curves were established for the samples in distilled water. Sodium trifluoroacetate (CF 3COONa) was used as an external chemical shift reference standard (0 ppm).…”