High-resolution NMR-based metabolic detection of microgram biopsies using a 1 mm HRμMAS probe

Yusuke Nishiyama (1, 2) , Yuki Endo (1) , Takahiro Nemoto (1, 2) , Anne-Karine Bouzier-Sore (3) , Alan Wong (4)

1 JEOL
2 RIKEN CLST - RIKEN Center for Life Science Technologies
3 CRMSB - Centre de résonance magnétique des systèmes biologiques
4 LSDRM - Laboratoire Structure et Dynamique par Résonance Magnétique (LCF)

A prototype 1 mm High-Resolution micro-Magic Angle Spinning (HRμMAS) probe is described. High quality 1 H NMR spectra were obtained from 490 μg of heterogeneous biospecimens, offering a rich-metabolite profiling. The results demonstrate the potential of HRμMAS as a new NMR analytical tool in metabolomics. Today 1 H HRMAS (High-Resolution Magic-Angle Spinning) NMR (Nuclear Magnetic Resonance) spectroscopy finds great success in laboratory studies of the metabolome in heterogeneous biospecimens such as human and animal biopsies, 1–3 intact cells 4 and whole organisms, 5,6 owing to the nearly non-destructive nature of the technique and the straightforward data acquisition. 7 However, since NMR spectroscopy is an inherently insensitive analytical technique, HRMAS relies on a large sample mass, typically 10–20 mg per NMR data. For this reason, 1 H HRMAS analysis can be a real challenge (or even impossible) when samples – such as cells, organisms and tissue biopsies – are scarce. Moreover, analysis of 10–20 mg of heterogeneous specimens may prevent the investigation of a specific cell. In contrast, the high degree of homogeneity inside a microscopic specimen can offer a more direct NMR spectral analysis and enable a straightforward metabolic evaluation. The immediate advantages of small sample mass (i.e. microgram) analyses are: (1) they simplify the sample preparations such as cultivation and extraction; and (2) offer precise specimen-specific analyses for exploring the invisible phenotypes. The most cost-effective approach to microscopic NMR detection is the use of a miniature detection coil (μcoil). With this technique, the coil is in close proximity to the microscopic sample optimizing the filling-factor (the ratio of the sample volume to the coil detection volume). 8 Fabricating a μcoil for HRMAS analyses is no easy task, especially without sacrificing detection sensitivity and spectral resolution. 9 The commercial μMAS systems currently available (i.e. 0.7 mm Bruker MAS and 0.75 mm JEOL MAS) are designed for solid materials but do not offer adequate spectral resolution (0.002 ppm) for metabolic investigations. Today, the only approach to μMAS for metabolome analyses is the use of an inductively coupled High-Resolution Magic-Angle Coil Spinning (HRMACS) μcoil. 10 The HRMACS technique uses a secondary tuned circuit (i.e. μcoil-resonator), designed to fit inside a standard 4 mm MAS rotor, to convert the standard large volume MAS system into a high-resolution capable μMAS probe. 11,12 The use of HRMACS has shown

Domaines: Matériaux

Yusuke Nishiyama, Yuki Endo, Takahiro Nemoto, Anne-Karine Bouzier-Sore, Alan Wong. High-resolution NMR-based metabolic detection of microgram biopsies using a 1 mm HRμMAS probe. Analyst, 2015, 140, pp.8097-8100. ⟨10.1039/c5an01810b⟩. ⟨cea-01232307⟩