Affordable but High-Sensitivity NMR Spectroscopy
NMR spectroscopy is one of the most versatile analytical methods in the chemical laboratory. Its ability to provide users with reliable and easy to interpret information on the composition of even the most complex samples has allowed NMR to become an analytical workhorse that cannot be replaced in various fields of chemistry, from organic chemistry to biomedical studies. Practitioners of these fields have become used to the main drawback of NMR – its relative lack of sensitivity. This not an issue for organic chemistry where several milligrams of an analyte can usually be used for NMR analysis. This would, however, be impossible, when studying low concentration metabolites in the body or in biofluids – these analytes appear at their natural concentration and there is not much we can do about it. The result is that low concentration metabolites of living organisms cannot be analyzed by NMR.
This PhD project will address this sensitivity limitation of NMR. The main supervisor has developed parahydrogen hyperpolarization based methods that boost NMR sensitivity by 1000-fold in biological sample analysis. This approach is built on dissolving a specific iridium metal-based catalyst in the NMR sample and bubbling parahydrogen gas through the sample in between NMR scans. The interaction of the gas and the catalyst with biological analytes will manipulate them to release orders of magnitude more NMR signal. This can be used to reduce the detectable concentration barrier and to make NMR measurements faster, recording more signal in a single NMR scan than a conventional NMR experiment would yield in thousands of scans. These NMR signal enhancement techniques are known as SABRE (10.1002/anie.201710406) and nh-PHIP (10.1021/acs.accounts.1c00796) in scientific literature.
The co-supervisor (Dr Lehmkuhl) is a leader in adapting parahydrogen hyperpolarization to affordable benchtop NMR spectrometers. Such machines are severalfold less costly to buy and operate, but are even less sensitive than regular NMR spectrometers. Combining them with hyperpolarization would allow to develop super-sensitive NMR methods on spectrometers that cost less. This leads to the essence of the project – combining the expertise in biological sample hyperpolarization with that of benchtop NMR spectrometers.
The PhD candidate will work on both high-end superconducting NMR instruments (in Tallinn) and compact benchtop machines (in KIT). The project will firstly focus on understanding the hyperpolarization process and its workings, optimizing it for different applications, metabolite classes, and biological sample types. Once accomplished (in Tallinn), we will port technology to benchtop instrumentation (in KIT). Development in Tallinn will focus on nh-PHIP, chemical development and understanding of the hyperpolarization process. Benchtop NMR experiments in KIT will develop nh-PHIP at low fields and also test SABRE in biological mixtures. The result will be a set on methods to detect biological information of benchtop NMR from samples that at the present state of the art cannot be analyzed on affordable spectrometers or sometimes cannot be analyzed by NMR at all. This project gives the PhD candidate an opportunity to participate in advancing the applications of NMR and expanding it towards new horizons in analytical chemistry and biomedical applications.
Indrek Reile (ORCID ID: 0000-0003-3278-7947) obtained a PhD in organic chemistry in TalTech in 2012 and specialized in NMR research during two postdocs. He moved to parahydrogen hyperpolarization (NMR sensitivity enhancement) methods and applications development while working with Prof Marco Tessari in the Radboud University in the Netherlands in 2014-2016. He started his own research group in Estonia in 2017 at the National Institute of Chemical Physics and Biophysics, developing hyperpolarization-based approaches for sensitivity enhanced NMR and metabolomics. The group has established itself as a pioneer in applying parahydrogen hyperpolarization for sensitivity enhanced NMR analysis of biological samples. We operate unique instrumentation that gives us access to NMR signals that others cannot detect. The team was among the first to conduct precise NMR analysis of human metabolites in a biofluid, wherein the analyte concentrations are orders of magnitude below the Limit of Detection of commercial NMR instrumentation. We are now building on this expertise, aiming to unlock the biological information from below the usual NMR sensitivity barrier.
The first PhD student of Dr Reile defended in 2024 with 5 papers published in 4 years. Dr Reile is currently supervising two PhD students and several MSc students. Students supervised by Dr Reile received awards from the Estonian National Contest for Student Research Publications in three consecutive years in 2021-2023.
Current research focus: Metabolomics, hyperpolarization, NMR, parahydrogen
Number of Publications: 40 (WoS)
Key Funding:
• Estonian Research Council starting grant PSG11
• Estonian Research Council mobility grant MPBTP51
• NICPB Development Fund grant
Awards, memberships:
• Representative of Estonia int the AMPERE committee, the governing body of magnetic resonance research in Europe
• Member of the Scientific Advisory Board of the Latvian NMR Centre
• Cambridge Isotope Laboratories, Inc. Research Award
Sören Lehmkuhl (ORCID ID: 0000-0002-1321-7677) is a Young Investigator Group leader at Karlsruhe Institute of Technology (KIT) in Germany since May 2024. He received his PhD in chemistry in 2019 from the RWTH Aachen University on the topic of NMR signal enhancement by hyperpolarization with parahydrogen. This was followed by 2.5 years as a Post Doc in the hyperpolarization laboratory of Prof. Dr. Thomas Theis at the North Carolina State University of Raleigh (USA), developing methodology and instrumentation for parahydrogen hyperpolarization.
Dr Lehmkuhl joined the Institute of Microstructure Technology (IMT) in KIT as an independent researcher and started his own research group after receiving an “Emmy Noether” grant from the German Research Foundation (DFG) in 2024. His research focuses on developing new analytical tools for NMR and MRI in chemistry, medicine and material science. The main focus is on increasing MR sensitivity in practical applications by parahydrogen hyperpolarization and resolution by the RASER approach. The laboratory has expertise both in the chemical and the engineering aspects of parahydrogen hyperpolarization. The project herein will also benefit from collaboration with world leading materials scientists, electrical and mechanical engineers in KIT for developing hyperpolarized NMR methods and instrumentation.
Kerti Ausmees holds a PhD in organic chemistry from Tallinn University of Technology (2013), with a later specialization in NMR methods and applications development. Her research focuses on adapting parahydrogen hyperpolarization for the identification of disease-related biomarkers that occur below the limit of detection of regular NMR. She is among the very few researchers who use hyperpolarization to boost sensitivity for NMR metabolomics to discover new biomarkers, improve diagnosis and deepen the understanding of disease mechanisms. She is among the leading experts in achieving compatibility of biological samples with NMR signal enhancement techniques, including parahydrogen hyperpolarization. Dr Ausmees has led the development of urine analysis by parahydrogen hyperpolarization (10.1039/D1CC05665D) and has supervised development of a protocol to detect nanomolar drug metabolites by hyperpolarized NMR (10.1021/acs.analchem.1c01281). She has previously supervised one PhD student (defended in 2024) and is currently supervising another PhD student.
The candidate should enjoy practical labwork at the interface of metalorganic and analytical chemistry. Work will include the study of organometallic catalysts and kinetics that influence hyperpolarization. Prior experience in metalorganic chemistry (possible work in inert gas atmosphere) is desirable, but focus will be on analytical chemistry methods that utilize metalorganic catalysts.
The candidate can interpret NMR spectra and has completed a course in principles of NMR. He/she should be able to communicate freely in English and be prepared to work in an interdisciplinary and multinational environment. Project will involve biological fluids and training for their safe handling.