Hyperpolarized 89Y complexes as pH sensitive NMR probes

Abstract

Hyperpolarization can increase the sensitivity of NMR/MRI experiments, but the primary limitation is the T(1) decay of magnetization. Due to its long T(1), the hyperpolarized (89)Y nucleus makes an excellent candidate as an in vivo spectroscopy/imaging probe. Here we report the (89)Y chemical shift dependence upon pH for two hyperpolarized (89)Y(III) complexes and demonstrate how such complexes can be used as sensitive spectroscopy/imaging agents to measure pH.

Figure 1

Ligands studied in this work.

Figure 2

⁸⁹Y chemical shift dispersion of hyperpolarized YDOTP () and YDO3A-NTs () as a function of pH (9.4 T and 25°C). The YDOTP data were collected from a single sample adjusted to different pH values after hyperpolarization while the YDO3A-NTs data required collection on different hyperpolarized samples due to rapid relaxation.

Figure 3

T₁ decay of hyperpolarized YDOTP magnetization at pH 4 (), 7 (), and 9 (), with n=2 and an error of approximately ±10 sec.