NMR Sensors for solids
MagicVoxel™ is an NMR sensor system that is inserted into magic angle coil spinning (MACS) NMR equipment to increase sensitivity and/or reduce sampling time. It overcomes a common limitation of solid state NMR measurements which is low sensitivity.
NMR users typically compensate low sensitivity by either of three methods, all of which are extremely onerous and costly:
1. Using complex hyperpolarization NMR equipment (DNP-NMR spectrometers)
2. Increasing the magnetic field (mostly not available or also extremely costly)
3. Increasing sampling period
The Voxalytic™ MACS insert offers a remarkable boost in solid state NMR sensitivity of 6-15 times, corresponding to a 36 to 225-fold reduction in measuring time. MACS opens up new opportunities simply through the smaller samples (minimum detection: nLODm = 2 x 1016 spin·Hz−1/2) and more efficient radio-frequency (RF) pulses, without the need to invest massively into new NMR equipment. The MACS are delivered with circular packaging which makes them easily insertable and removable into standard rotating tubes of different diameters as shown in the picture below.
The sensor is available either in single-resonance or double-resonances configuration for different magnetic nuclei (1H, 13C, 15N, 17O, etc) and magnetic B0 field strengths (40 MHz up to 900 MHz). Meanwhile, Voxalytic™ MACS provides high spectral resolution solid state NMR spectra through efficient and precise RF pulse. Voxalytic™ MACS is powerful in many conceivable applications, particularly for structural measurements of very small protein samples, 'metabolomics' studies of the biochemistry of microscopic tissue extracts.
HOW IT WORKS
Solid state NMR suffers an inherent drawback of low sensitivity and poor spectra resolution method because of the small differences of energy Boltzmann distribution and strong dipolar-dipolar interactions. In order to circumvent this problems, magic angle coil spinning methods are used involving fast spinning of both the sample and the miniaturized detector coil. The closer the coil to the material (= high filing factor) the larger is the detectable signal.
SolidVoxel™ is a packaged detector system that can conveniently be filled with the sample (needing much less sample material than traditional tubes) and is inserted either directly into the rotor or via an insertion holder into a spinning NMR tube. It yields higher sensitivity than conventional systems due to the excellent filling factor of the experimental setup. The insertion into the rotor takes only a few seconds and renders measurement very time-efficient.
Local magnetic field inhomogeneities introduced in the sample by the proximity of the wire are eliminated by spinning the microcoil at the magic angle, simultaneously with the solid sample.
The measured signal is transmitted into the detector coil of the NMR equipment via inductive coupling, i.e., no additional wiring or connection is required.
Sensitivity enhancement: 6 – 15. (saving 36 – 225-fold work time)
Mass sensitivity: Sm = 230 µmol−1·Hz1/2.
Sample weight above 100 μg
Limit of detection: nLODm = 2E16 spin·Hz−1/2
Single or Double NMR resonance, e.g. 1H, 13C, 15N, 19F & etc.
Fully customisable for different NMR rotor & magnetic field strengths.
VoxalyticTM MACS covers a wide area of potential applications both in life sciences and analytical chemistry. The subsequenly-listed table summarises high potential applications. Solid-State NMR Spectroscopy involves the analysis of solids and semi-solids:
Organics, including fine chemicals and pharmaceutics.
Catalysis, and reactive intermediates.
Mixtures, such as: pharmaceutical formulations.
Biomass, including plant stalks and leaves.
Energy materials, such as coal, shale, and battery materials.
Polymer Structure and Silicate research
Peptides and proteins.
Membranes, tissues, and gels.
ILLUSTRATIVE MEASUREMENT OUTPUTS
1H SPECTRUM OF ADAMANTANE
The spectra were acquired in a 500 MHz system with pulse length of 7 µs and energy of 1W.
1H NMR SPECTRA OF DROSOPHILA PUPAE
The spectra was acquired with a total of three pupae in a 400 µm-microcoil coupled with a standard 7-mm MAS probe, spinning at 500 Hz for the single-pulse experiment, and at 371 Hz for the PASS experiment. The total experimental time for the PASS experiment is about 1 hour. Peak assignment (1) Lipid –CH3 (2) fatty acid –(CH2)n (3) lactate CH3(4) Lipid –CH2-CH2-CO– (5) Lipid–CH = CH-CH2-CH2– (6) Lipid –CH2-CH2-CO–. (Citation: Badilita V, Fassbender B, Kratt K, Wong A, Bonhomme C, Sakellariou D, et al. (2012) PLoS ONE 7(8): e42848.)
CUSTOMIZATION AND FURTHER INFORMATION
We deliver Voxalytic MACS inserts for different magnetic nuclei (1H, 13C, 15N, 19F, 17O) and magnetic B0 field strengths (40 MHz up to 900 MHz) and the Solid State NMR rotor diameter above 2.5 mm. We do, however, offer customization services to suit customer requirements.