Hyperpolarized NMR Probes for Biological Assays

Abstract

During the last decade, the development of nuclear spin polarization enhanced (hyperpolarized) molecular probes has opened up new opportunities for studying the inner workings of living cells in real time. The hyperpolarized probes are produced ex situ, introduced into biological systems and detected with high sensitivity and contrast against background signals using high resolution NMR spectroscopy. A variety of natural, derivatized and designed hyperpolarized probes has emerged for diverse biological studies including assays of intracellular reaction progression, pathway kinetics, probe uptake and export, pH, redox state, reactive oxygen species, ion concentrations, drug efficacy or oncogenic signaling. These probes are readily used directly under natural conditions in biofluids and are often directly developed and optimized for cellular assays, thus leaving little doubt about their specificity and utility under biologically relevant conditions. Hyperpolarized molecular probes for biological NMR spectroscopy enable the unbiased detection of complex processes by virtue of the high spectral resolution, structural specificity and quantifiability of NMR signals. Here, we provide a survey of strategies used for the selection, design and use of hyperpolarized NMR probes in biological assays, and describe current limitations and developments.

Implementation and Characterization of Flow Injection in Dissolution Dynamic Nuclear Polarization NMR Spectroscopy

“…[1,2] In liquid state NMR, dissolution dynamic nuclear polarization (D-DNP) is interesting for its versatility in polarizing various molecules and nuclei. A distinguishing feature of D-DNP is the separation of a location for hyperpolarization from a location for performing the NMR experiment.…”

Optimizing dissolution dynamic nuclear polarization

“…One can cite amongst many other publications in vitro or in-cell studies [13,14], drug screening [15], and monitoring of chemical reactions including the detection of intermediates [16]. Further d-DNP NMR applications can be found in reference [17]. The coupling with ultrafast One important concern in d-DNP experiments is that once dissolved, the hyperpolarization decays with the nuclear spin-lattice relaxation time T 1 .…”

Rapid-melt Dynamic Nuclear Polarization

“…Other uses of dissolution DNP include biomolecular NMR [63,64], the study of biological assays [65,66] and the detection of low concentration reaction intermediates [67]. Only a few analytical application have been demonstrated [120].…”

“…Other applications include biomolecular NMR [63,64], biological assays [65,66], detection of reaction intermediates having low concentrations [67], protein folding [68], and drug screening [69]. The use of dissolution DNP in a clinical environment is under development [70].…”

“…Details of these methods can be found elsewhere [91,92]. Dissolution DNP is used for metabolic imaging, biomolecular NMR [63,64] and biological assays [65,66] while MAS-DNP has found its applications in surface chemistry, protein structure determination and polymer studies [41,40]. Dissolution DNP is limited to slow relaxing nuclei and only a few number of scans are possible within the T 1 of the nuclei of interest [70].…”