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Lysak DH, Bermel W, Moxley-Paquette V, Michal C, Ghosh-Biswas R, Soong R, Nashman B, Lacerda A, Simpson AJ. Cutting without a Knife: A Slice-Selective 2D 1H- 13C HSQC NMR Sequence for the Analysis of Inhomogeneous Samples. Anal Chem 2023; 95:14392-14401. [PMID: 37713676 DOI: 10.1021/acs.analchem.3c02756] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/17/2023]
Abstract
Nuclear magnetic resonance (NMR) is a powerful technique with applications ranging from small molecule structure elucidation to metabolomics studies of living organisms. Typically, solution-state NMR requires a homogeneous liquid, and the whole sample is analyzed as a single entity. While adequate for homogeneous samples, such an approach is limited if the composition varies as would be the case in samples that are naturally heterogeneous or layered. In complex samples such as living organisms, magnetic susceptibility distortions lead to broad 1H line shapes, and thus, the additional spectral dispersion afforded by 2D heteronuclear experiments is often required for metabolite discrimination. Here, a novel, slice-selective 2D, 1H-13C heteronuclear single quantum coherence (HSQC) sequence was developed that exclusively employs shaped pulses such that only spins in the desired volume are perturbed. In turn, this permits multiple volumes in the tube to be studied during a single relaxation delay, increasing sensitivity and throughput. The approach is first demonstrated on standards and then used to isolate specific sample/sensor elements from a microcoil array and finally study slices within a living earthworm, allowing metabolite changes to be discerned with feeding. Overall, slice-selective NMR is demonstrated to have significant potential for the study of layered and other inhomogeneous samples of varying complexity. In particular, its ability to select subelements is an important step toward developing microcoil receive-only arrays to study environmental toxicity in tiny eggs, cells, and neonates, whereas localization in larger living species could help better correlate toxin-induced biochemical responses to the physical localities or organs involved.
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Affiliation(s)
- Daniel H Lysak
- Environmental NMR Center, Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada
| | - Wolfgang Bermel
- Bruker BioSpin GmbH, Rudolf-Plank-Str. 23, 76275 Ettlingen, Germany
| | - Vincent Moxley-Paquette
- Environmental NMR Center, Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada
| | - Carl Michal
- Department of Physics and Astronomy, University of British Columbia, 6224 Agricultural Road, Vancouver, BC V6T 1Z1, Canada
| | - Rajshree Ghosh-Biswas
- Environmental NMR Center, Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada
| | - Ronald Soong
- Environmental NMR Center, Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada
| | - Ben Nashman
- Synex Medical, 2 Bloor Street E, Suite 310, Toronto, ON M4W 1A8,Canada
| | - Andressa Lacerda
- Synex Medical, 2 Bloor Street E, Suite 310, Toronto, ON M4W 1A8,Canada
| | - Andre J Simpson
- Environmental NMR Center, Department of Physical and Environmental Sciences, University of Toronto Scarborough, 1265 Military Trail, Toronto, ON M1C 1A4, Canada
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Temporal and spatial characterisation of protein liquid-liquid phase separation using NMR spectroscopy. Nat Commun 2022; 13:1767. [PMID: 35365630 PMCID: PMC8976059 DOI: 10.1038/s41467-022-29408-z] [Citation(s) in RCA: 6] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2021] [Accepted: 03/11/2022] [Indexed: 12/15/2022] Open
Abstract
Liquid-liquid phase separation (LLPS) of protein solutions is increasingly recognised as an important phenomenon in cell biology and biotechnology. However, opalescence and concentration fluctuations render LLPS difficult to study, particularly when characterising the kinetics of the phase transition and layer separation. Here, we demonstrate the use of a probe molecule trifluoroethanol (TFE) to characterise the kinetics of protein LLPS by NMR spectroscopy. The chemical shift and linewidth of the probe molecule are sensitive to local protein concentration, with this sensitivity resulting in different characteristic signals arising from the dense and lean phases. Monitoring of these probe signals by conventional bulk-detection 19F NMR reports on the formation and evolution of both phases throughout the sample, including their concentrations and volumes. Meanwhile, spatially-selective 19F NMR, in which spectra are recorded from smaller slices of the sample, was used to track the distribution of the different phases during layer separation. This experimental strategy enables comprehensive characterisation of the process and kinetics of LLPS, and may be useful to study phase separation in protein systems as a function of their environment.
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Wisniewska MA, Seland JG. Investigating structure-dependent diffusion in hydrogels using spatially resolved NMR spectroscopy. J Colloid Interface Sci 2019; 533:671-677. [PMID: 30195115 DOI: 10.1016/j.jcis.2018.08.112] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2018] [Revised: 08/28/2018] [Accepted: 08/29/2018] [Indexed: 10/28/2022]
Abstract
HYPOTHESIS Incorporation of the drug-loaded surfactant micelles into polymer hydrogels is a common method used to achieve controlled drug delivery. The characterization of the diffusion processes in drug delivery systems is critical in order to tune the drug loading and release. EXPERIMENTS We present a simple and efficient NMR protocol to investigate the transport of the surfactant molecules in hydrogels on micro- and macroscale under non-equilibrium conditions. Our experimental protocol is based on a combination of 1H 1D NMR chemical shift imaging and slice-selective diffusion experiments, which enables determination of the mutual and self-diffusion coefficients of the surfactant in the non-equilibrium hydrogel-based system within the same short time frame. FINDINGS Our results show that the self-diffusion coefficient of the positively charged surfactant in the hydrogel (Dsgel) decreases with the increasing surfactant concentration until it reaches a plateau value of 6.6±0.5×10-11m2s-1. The surfactant self-diffusion in the solution (Dssln) remains constant over the experiment with an average value of 6.7±0.3×10-11m2s-1. The surfactant mutual diffusion coefficient obtained from 1D chemical shift imaging in this hydrogel system (Dm) is 7.7±0.5×10-11m2s-1. Correlation of the localized Ds to the 1D chemical shift images gives insight into the structure-dependent diffusional behavior of surfactant molecules in the hydrogel. This NMR protocol will be of great value in studies of concentration dependent structures on the interfaces between two immiscible liquids.
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