Efficient Parahydrogen-Induced 13 C Hyperpolarization on a Microfluidic Device.

We show the direct production and detection of 13 C-hyperpolarized fumarate by parahydrogen-induced polarization (PHIP) in a microfluidic lab-on-a-chip (LoC) device and achieve 8.5% 13 C polarization. This is the first demonstration of 13 C-hyperpolarization of a metabolite by PHIP in a microfluidic device. LoC technology allows the culture of mammalian cells in a highly controlled environment, providing an important tool for the life sciences. In-situ preparation of hyperpolarized metabolites greatly enhances the ability to quantify metabolic processes in such systems by microfluidic NMR. PHIP of 1 H nuclei has been successfully implemented in microfluidic systems, with mass sensitivities in the range of pmol/s. However, metabolic NMR requires high-yield production of hyperpolarized metabolites with longer spin life times than is possible with 1 H. This can be achieved by transfer of the polarization onto 13 C nuclei, which exhibit much longer T 1 relaxation times. We report an improved microfluidic PHIP device, optimized using a finite element model, that enables the direct and efficient production of 13 C-hyperpolarized fumarate.