Efficient Parahydrogen-Induced ¹³C Hyperpolarization on a Microfluidic Device

We show the direct production and detection of ¹³C-hyperpolarized fumarate by parahydrogen-induced polarization (PHIP) in a microfluidic lab-on-a-chip (LoC) device and achieve 8.5% ¹³C polarization. This is the first demonstration of ¹³C-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 ¹H 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 ¹H. This can be achieved by transfer of the polarization onto ¹³C nuclei, which exhibit much longer T₁ relaxation times. We report an improved microfluidic PHIP device, optimized using a finite element model, that enables the direct and efficient production of ¹³C-hyperpolarized fumarate.