Magic-angle spinning and polarization transfer in proton-enhanced NMR

Stejskal, E. O.; Schaefer, Jacob; Waugh, J. S.

doi:10.1016/0022-2364(77)90260-8

Cited by 303 publications

(331 citation statements)

References 10 publications

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“…The sample temperature was calibrated using ethylene glycol [15] and determined to be 7.2 and 10.0 °C for MAS rates (ν R ) of 36 kHz and 39 kHz respectively. During cross polarization (CP) [16,17], the 1 H and 15 N nutation frequencies are 2.5 and 1.5 times the MAS rate, respecively. For n.a.…”

Section: Methodsmentioning

confidence: 99%

High-performance solvent suppression for proton detected solid-state NMR

Zhou

Rienstra

2008

Journal of Magnetic Resonance

214

192

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High-sensitivity proton-detected experiments in solid-state NMR have been recently demonstrated in proton-diluted proteins as well as fully protonated samples under fast magic-angle spinning. One key element for performing successful proton detection is effective solvent suppression achieved by pulsed field gradients (PFG) and/or saturation pulses. Here we report a high-performance solvent suppression method that attenuates multiple solvent signals simultaneously by more than a factor of 10,000, achieved by an optimized combination of homospoil gradients and supercycled saturation pulses. This method, which we call Multiple Intense Solvent Suppression Intended for Sensitive Spectroscopic Investigation of Protonated Proteins, Instantly (MISSISSIPPI), can be applied without a PFG probe. It opens up new opportunities for two-dimensional heteronuclear correlation spectroscopy of hydrated proteins at natural abundance as well as high-sensitivity and multidimensional experimental investigation of protein-solvent interactions.

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Section: Methodsmentioning

confidence: 99%

High-performance solvent suppression for proton detected solid-state NMR

Zhou

Rienstra

2008

Journal of Magnetic Resonance

214

192

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“…All 13 C spectra were collected using a Chemagnetics CMX-300 spectrometer using variable amplitude cross-polarization (VACP) [24], magic-angle spinning (MAS) [25], and two pulse phase modulation (TPPM) decoupling [26]. Samples were packed into 7 mm o.d.…”

Section: Solid-state Nmr Spectroscopymentioning

confidence: 99%

NanoCipro encapsulation in monodisperse large porous PLGA microparticles

Arnold

Gorman

Schieber

et al. 2007

Journal of Controlled Release

119

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Pulmonary drug delivery of controlled release formulations may provide an effective adjunct approach to orally delivered antibiotics for clearing persistent lung infections. Dry powder formulations for this indication should possess characteristics including; effective deposition to infected lung compartments, persistence at the infection site, and steady release of antibiotic. Large porous particles (∼10-15 μm) have demonstrated effective lung deposition and enhanced lung residence as a result of their large diameter and reduced clearance by macrophages in comparison to small microparticles (∼1-5 μm). In this report, Precision Particle Fabrication technology was used to create monodisperse large porous particles of poly(D,L-lactic-co-glycolic acid) (PLGA) utilizing oils as extractable porogens. After extraction, the resulting large porous PLGA particles exhibited a low density and a web-like or hollow interior depending on porogen concentration and type, respectively. Ciprofloxacin nanoparticles (nanoCipro) created by homogenization in dichloromethane, possessed a polymorph with a decreased melting temperature. Encapsulating nanoCipro in large porous PLGA particles resulted in a steady release of ciprofloxacin that was extended for larger particle diameters and for the solid particle morphology in comparison to large porous particles. The encapsulation efficiency of nanoCipro was quite low and factors impacting the entrapment of nanoparticles during particle formation were elucidated. A dry powder formulation with the potential to control particle deposition and sustain release to the lung was developed and insight to improve nanoparticle encapsulation is discussed.

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“…Spatial inhomogeneity in the amplitude of the rf field over the sample volume; 2. Spatial inhomogeneity in the direction of the rf field over the sample volume, which translates into a phase modulation of the rf field as the sample rotates; 25,86,87 3. Transients in the rf field upon changes in the driving field amplitude or phase, caused by the limited frequency bandwidth of the probe; 85,88 4.…”

Section: Rf Imperfectionsmentioning

confidence: 99%

“…The situation changed at the end of the 1970s, when it was found that magic-angle spinning dramatically narrowed the protondecoupled NMR peaks of isolated 13 C spins in organic solids. 3 The 13 C peaks split up into narrow 'spinning sidebands', even though the spinning frequency was much smaller than the chemical shift anisotropy (CSA). MAS, in combination with Hartmann-Hahn cross-polarization and heteronuclear decoupling, became a standard method for examining the NMR spectra of rare spin species such as 13 C and 15 N in solids.…”

Section: Introductionmentioning

confidence: 99%