Artikel des Tages: Slow magic-angle coil spinning: A high-sensitivity and high-resolution NMR strategy for microscopic biological specimens

Der heutige Artikel des Tages widmet sich einer eher technischen Fragestellung.
Erschienen ist er im Februar 2010 in der Zeitschrift Magnetic Resonance in Medicine, Vol. 63, Teil 2, Seiten 269-274.

High-resolution magic-angle spinning has become a valuable tool to study biologic samples; however, there are only a few high-resolution magic-angle spinning methodologies that have been explored specifically to deal with small semisolid biomaterials such as tissues. Here, we report a novel high-resolution 1H NMR spectroscopic approach using magic-angle coil spinning. We demonstrate its potential for intact tissues by combining a resonant microcoil with a large-volume commercial magic-angle spinning rotor, where the microcoil offers incredible sensitivity and the large-volume magic-angle spinning rotor provides stable slow magic-angle spinning. This approach provides high-resolution spectra with high sensitivity and the preservation of living biologic specimens for an accurate chemical analysis.

Die Autoren sind Mitglieder des Commissariat à l'Énergie Atomique Saclay, in Gif-sur-Yvette, Frankreich.

Online abrufbar ist der Artikel über DOI 10.1002/mrm.22231.

Artikel des Tages: Protein polymer MRI contrast agents: Longitudinal analysis of biomaterials in vivo

Wir bleiben bei den Polymeren, widmen uns heute aber einer Anwendung in der Medizin.

Abstract:

Despite recent advances in tissue engineering to regenerate biological function by combining cells with material supports, development is hindered by inadequate techniques for characterizing biomaterials in vivo. Magnetic resonance imaging is a tomographic technique with high temporal and spatial resolution and represents an excellent imaging modality for longitudinal noninvasive assessment of biomaterials in vivo. To distinguish biomaterials from surrounding tissues for magnetic resonance imaging, protein polymer contrast agents were developed and incorporated into hydrogels. In vitro and in vivo images of protein polymer hydrogels, with and without covalently incorporated protein polymer contrast agents, were acquired by magnetic resonance imaging. T1 values of the labeled gels were consistently lower when protein polymer contrast agents were included. As a result, the protein polymer contrast agent hydrogels facilitated fate tracking, quantification of degradation, and detection of immune response in vivo. For the duration of the in vivo study, the protein polymer contrast agent-containing hydrogels could be distinguished from adjacent tissues and from the foreign body response surrounding the gels. The hydrogels containing protein polymer contrast agent have a contrast-to-noise ratio 2-fold greater than hydrogels without protein polymer contrast agent. In the absence of the protein polymer contrast agent, hydrogels cannot be distinguished by the end of the gel lifetime.

Erschienen ist der Artikel in der Zeitschrift Magnetic Resonance in Medicine, Volume 65, Teil 1, Seiten 220-228. Online abrufbar ist er über DOI 10.1002/mrm.22587.

Artikel des Tages: Heteronuclear chemical shift correlation and J-resolved MAS NMR spectroscopy of lipid membranes

Nach eineinhalb Monaten Weihnachtspause gibt es hier auch endlich wieder einen Artikel des Tages.

Diesmal ist das Thema in der Festkörperphysik zu finden: es geht um NMR-Spektroskopie an DOPC-Membranen, unter der Anwendung der LG-HETCOR-LG-Methode.

Abstract:

Direct observation of J-couplings remains a challenge in high-resolution solid-state NMR. In some cases, it is possible to use Lee–Goldburg (LG) homonuclear decoupling during rare spin observation in MAS NMR correlation spectroscopy of lipid membranes to obtain J-resolved spectra in the direct dimension. In one simple implementation, a wide line separation-type
¹³C-¹H HETCOR can provide high-resolution ¹H/¹³C spectra, which are J-resolved in both dimensions. Coupling constants, ¹J_CH, obtained from ¹H doublets, can be compared with scaled ¹J^θ_CH obtained from the ¹³C multiplets to assess the LG-values efficiency and scaling factor. The use of homonuclear decoupling during proton evolution, LG-HETCOR-LG, can provide J-values, at least in the rare spin dimension, and allows measurements in less mobile membrane environments. The LG-decoupled spectroscopic approach is demonstrated on pure dioleoylphosphatidylcholine (DOPC) membranes and used to investigate lipid mixtures of DOPC/cholesterol and DOPC/cholesterol/sphingomyelin.

Die Autoren sind Mitarbeiter der Universität von Nottingham in Großbritannien.

Erschienen ist der Artikel im Magazin Magnetic Resonance in Chemistry, Volume 48, Teil 12, Seiten 925–934. Online zu finden ist er außerdem unter DOI 10.1002/mrc.2690.