Parahydrogen-based NMR signal amplification by reversible exchange (SABRE): Recent advances and applications

Signal amplification by reversible exchange (SABRE) is a rapidly developing nuclear magnetic resonance (NMR) hyperpolarization technique utilizing parahydrogen for dramatic increase of NMR sensitivity to benefit its biomedical and analytic applications. This mini-review covers the most important methodological advances of SABRE with the focus on recent developments. We discuss the mechanistic aspects of SABRE effects, hyperpolarization of protons and heteronuclei including the novel SABRE-Relay approach, the ongoing work to make SABRE biocompatible, the analytical applications, the advances in instrumentation and, finally, more exotic developments such as the low-field detection of SABRE and the SABRE-initiated radiofrequency amplification by stimulated emission of radiation (RASER) effects.