Parahydrogen-induced polarization relayed via proton exchange

TL;DR

This paper introduces PHIP-X, a novel hyperpolarization technique that combines parahydrogen-induced polarization with proton exchange to enhance NMR signals across various molecules efficiently and cost-effectively.

Contribution

The study presents a new hyperpolarization method, PHIP-X, which enables flexible and efficient polarization transfer to diverse molecules using low-cost hydrogenative parahydrogen-induced polarization combined with proton exchange.

Findings

Effective hyperpolarization of alcohols, water, lactate, and pyruvate.

Significant signal enhancement with only ~3 mM transfer agent.

Potential for broader NMR applications beyond thermal polarization limits.

Abstract

The sensitivity of NMR and MRI can be boosted via hyperpolarization of nuclear spins. However, current methods are costly, polarization is relatively low, or applicability is limited. Here, we report a new hyperpolarization method combining the low-cost, high polarization of hydrogenative parahydrogen-induced polarization (PHIP) with the flexibility of polarization transfer via proton exchange. The new method can be used to polarize various molecules, including alcohols, water, lactate, and pyruvate. On average, only $\approx$3 mM of a hyperpolarized transfer agent was sufficient to significantly enhance the signal of $\approx$100 mM of target molecules via proton exchange. Thus, hydrogenative parahydrogen-induced hyperpolarization with proton exchange (PHIP-X) provides a new avenue for NMR applications beyond the limits imposed by thermal polarization.