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1.7 mm Micro-Probehead for small volume NMR Spectroscopic Investigations

English title 1.7 mm Micro-Probehead for small volume NMR Spectroscopic Investigations
Applicant Furrer Julien
Number 139078
Funding scheme R'EQUIP
Research institution Departement für Chemie, Biochemie und Pharmazie Universität Bern
Institution of higher education University of Berne - BE
Main discipline Organic Chemistry
Start/End 01.03.2012 - 28.02.2013
Approved amount 62'000.00
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All Disciplines (2)

Discipline
Organic Chemistry
Biochemistry

Keywords (5)

NMR; Micro Probehead; small volume; sensitivity; structural studies

Lay Summary (English)

Lead
Lay summary
Today, the conventional NMR sample still consists of a cylindrical glass tube of 5-mm outer
diameter and ~20-cm length with a sample fill volume of 500-600 ?L. Ultra-high-field
NMR spectrometers up to 900 MHz and cryogenically cooled detector coils are available,
but, nevertheless, structural analysis of mass-limited samples in the microgram
range, e.g., natural product isolates, DNAs, proteins, drug metabolites, still remains
challenging. Recently 1- and 1.7-mm microprobes with 5- and 30-??L fill volume, respectively,
were developed. These new microliter probes allow the measurement of
one-dimensional 1H NMR and two-dimensional heteronuclear NMR spectra with a few
nanomoles (micrograms) of compound with high sensitivity, speed, and quality.1 The
introduction of these small volume probeheads has been a breakthrough for NMR
spectroscopy for structure elucidation of natural products and metabolic research.
These probeheads offer also advantages for linking chromatographic methods to NMR.
Another advantage of these microprobes is that with decreasing diameter of the NMR
detector coil, the NMR mass sensitivity (S/N per mole) increases approximately with
1/d. Thus, as compared to a standard 5 mm probehead, a 1.7 mm probehead has a
mass sensitivity of 2, i.e. the required sample amount can be divided by two for the
same results in term of signal-to-noise.2
Additional non-negligible advantages of these low-volume probes are that signals
from solvent impurities are much less prominent with decreasing sample volume.
For electrically conductive solvents such as salt-containing solutions there is also a
reduction of the “solvent noise” when going to smaller volumes. In addition, the
amount of expensive deuterated solvents can be dramatically reduced (often by 2 orders
of magnitude). In addition, signals from solvent impurities are much less prominent
with decreasing sample volume. For electrically conductive solvents such as saltcontaining
solutions there is also a reduction of the “solvent noise” when going to
smaller volumes.2
For the investigators of this proposal, the  equipment will open
new fields to NMR spectroscopic research that are currently not feasible with the current
equipment available. Owing to the broad variety of samples falling into the application
field of a microprobe, e.g. proteins, DNAs, natural products, a diversified interdisciplinary
usership will be able to benefit from this microprobe. In view of the current
countrywide lack of accessibility to such a dedicated probehead within the Swiss
university institutions, the equipment will close this gap and will enable us to keep
up with modern state-of-the-art technologies, explore new applications fields and extend
our competences.
Direct link to Lay Summary Last update: 21.02.2013

Responsible applicant and co-applicants

Collaboration

Group / person Country
Types of collaboration
G. Süss-Fink / Université Neuchâtel Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof J.-L- Reymond Université Berne Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Dr A. Stocker / Université Bern Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication
Prof. R. Häner / Université Bern Switzerland (Europe)
- in-depth/constructive exchanges on approaches, methods or results
- Publication

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125020 Peptide and Glycopeptide Dendrimers as Artificial Proteins 01.04.2009 Project funding (Div. I-III)
130373 Chemically modified Oligonucleotides for Biotechnology and Material Sciences 01.04.2010 Project funding (Div. I-III)
127500 Host defence peptides of the innate immune system and in the venom of the spider Cupiennius salei 01.12.2009 Project funding (Div. I-III)
132581 DNA-assisted self-organization of aromatic chromophores 01.10.2010 Project funding (Div. I-III)
131867 NMR investigation of cellular targets and mechanistic profiles of ruthenium-based drugs 01.01.2011 Project funding (Div. I-III)
144420 Bridged Dinuclear Arene Ruthenium Complexes: Cellular Targets and Mechanistic Profiles Investigated by NMR 01.01.2013 Project funding (Div. I-III)
173718 Ruthenium Complexes for the Treatment of Protozoan Diseases of Medical and Veterinary Importance 01.09.2017 Sinergia

Abstract

This proposal aims at obtaining financial support for the purchase of a 1.7mm Micro-probehead (Small volume probe) and its dedicated sample changer to be implemented in the NMR lab of the Chemistry Department at the University of Bern. Today the conventional NMR sample still consists of a cylindrical glass tube of 5-mm outer diameter and ~20-cm length with a sample fill volume of 500-600 ?L. Ultra-high-field NMR spectrometers up to 900 MHz and cryogenically cooled detector coils are available, but, nevertheless, structural analysis of mass-limited samples in the microgram range, e.g., natural product isolates, DNAs, proteins, drug metabolites, still remains challenging. Recently 1- and 1.7-mm microprobes with 5- and 30-??L fill volume, respectively, were developed. These new microliter probes allow the measurement of one-dimensional 1H NMR and two-dimensional heteronuclear NMR spectra with a few nanomoles (micrograms) of compound with high sensitivity, speed, and quality. The introduction of these small volume probeheads has been a breakthrough for NMR spectroscopy for structure elucidation of natural products and metabolic research. These probeheads offer also advantages for linking chromatographic methods to NMR. Another advantage of these microprobes is that with decreasing diameter of the NMR detector coil, the NMR mass sensitivity (S/N per mole) increases approximately with 1/d. Thus, as compared to a standard 5 mm probehead, a 1.7 mm probehead has a mass sensitivity of 2, i.e. the required sample amount can be divided by two for the same results in term of signal-to-noise.
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