Study of synthetic diamonds by dynamic nuclear polarization-enhanced13C nuclear magnetic resonance spectroscopy

Yang, Bojun; Zhou, Jianrong; Hu, Hongming; Li, L.; Qiu, Jian; Guo, Junbo; He, Pengbo; Lu, Jun‐Sheng; Ye, Chen

doi:10.1007/bf03161961

Cited by 7 publications

(4 citation statements)

References 15 publications

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“…The foundation for DNP-enhanced, high-resolution ssNMR has been laid by seminal work from the Wind laboratory in the 1980s. − Most notably, the development of a MAS DNP setup was a crucial step toward biomolecular applicability . Later work by the Schaefer and Zhou laboratories helped to establish MAS DNP as a powerful technique for the investigation of polymers and materials by homogeneous doping with radicals or by using endogenous defects. − As these early developments were focused toward bulk samples at low magnetic fields up to 1.9 T (54 GHz e – , 80 MHz 1 H), applications for diluted biomolecular systems in an aqueous solution required a different approach regarding sample constitution, doping and high magnetic field. Nevertheless, these early experiments have provided important concepts such as the wide and uniform spreading of 1 H hyperpolarization by spin diffusion in DNP-enhanced CPMAS experiments as well as localization of polarization in DPMAS experiments. ,− …”

Section: Biomolecular Dnp From Early Development To Presentmentioning

confidence: 99%

Dynamic Nuclear Polarization for Sensitivity Enhancement in Biomolecular Solid-State NMR

et al. 2022

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Solid-state NMR with magic-angle spinning (MAS) is an important method in structural biology. While NMR can provide invaluable information about local geometry on an atomic scale even for large biomolecular assemblies lacking long-range order, it is often limited by low sensitivity due to small nuclear spin polarization in thermal equilibrium. Dynamic nuclear polarization (DNP) has evolved during the last decades to become a powerful method capable of increasing this sensitivity by two to three orders of magnitude, thereby reducing the valuable experimental time from weeks or months to just hours or days; in many cases, this allows experiments that would be otherwise completely unfeasible. In this review, we give an overview of the developments that have opened the field for DNP-enhanced biomolecular solid-state NMR including state-of-the-art applications at fast MAS and high magnetic field. We present DNP mechanisms, polarizing agents, and sample constitution methods suitable for biomolecules. A wide field of biomolecular NMR applications is covered including membrane proteins, amyloid fibrils, large biomolecular assemblies, and biomaterials. Finally, we present perspectives and recent developments that may shape the field of biomolecular DNP in the future.

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Section: Biomolecular Dnp From Early Development To Presentmentioning

confidence: 99%

Dynamic Nuclear Polarization for Sensitivity Enhancement in Biomolecular Solid-State NMR

et al. 2022

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“…Furthermore, the high polarization of unpaired electrons can be transferred via hyperfine interactions to the nearby nuclei, thus enhancing the NMR signal. In the case of diamond, this polarization transfer has been achieved either by continuous-wave or pulsed microwave (μw) irradiation near the electron paramagnetic resonance (EPR) frequency using the dynamic nuclear polarization (DNP) phenomenon ,− or by optical pumping with visible light of the electronic transition of nitrogen-vacancy (NV) centers. − So far, optical pumping has only been achieved for diamond single crystals. Conversely, DNP-enhanced 13 C NMR for static samples has been reported for diamond single crystals, ,,− and chemical vapor deposited diamond films , at low static magnetic field, B 0 ≤ 1.9 T and room temperature ( T ), as well as for polycrystalline diamond samples of various particle sizes, including NDs, at B 0 = 3.35 T and T ≤ 1.9 K. , A DNP signal enhancement larger than 330 has also been measured for a diamond single crystal at B 0 = 9.4 T, T = 105 K and under static conditions…”

Section: Introductionmentioning

confidence: 99%

NMR and EPR Characterization of Functionalized Nanodiamonds

Presti

Thankamony²,

Alauzun

et al. 2015

J. Phys. Chem. C

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We investigated the potential of solid-state NMR using magic angle spinning (MAS) with and without dynamic nuclear polarization (DNP) and electron paramagnetic resonance (EPR) for the characterization of functionalized nanodiamonds (NDs). We showed that conventional 1 H, 31 P, and 13 C solid-state NMR spectra allow differentiating in a straightforward way NDs from commercial sources and custom-made NDs bearing aromatic or aliphatic phosphonate moieties at their surface. Besides, the short nuclear relaxation times prove the close proximity between the endogenous paramagnetic centers of NDs and the grafted organic moieties. EPR spectra confirmed the presence of these paramagnetic centers in functionalized NDs, which are centered on dangling bonds as well as a few N 0 defects, corresponding to the substitution of carbon atoms by nitrogen ones. Hyperfine sublevel correlation spectroscopy indicates that the N 0 paramagnetic centers are mostly located in the disordered shell of NDs. Preliminary DNP-enhanced NMR experiments at 9.4 T and 100 K under MAS have shown a lack of significant DNP enhancement, which can be attributed to the short relaxation times of the unpaired electrons and the nuclei in NDs. When using exogenous polarizing agents, the endogenous unpaired electrons contribute to a leakage of polarization. Furthermore, low temperatures lead to a broadening of NMR signals. It therefore appears that conventional direct excitation remains the NMR method of choice for the characterization of functionalized NDs. ■ INTRODUCTIONNanodiamonds (NDs), that is, diamond particles with a diameter smaller than 100 nm, are receiving considerable attention due to their remarkable hardness and thermal conductivity, luminescence properties, chemical inertness, and biocompatibility. 1−6 For instance, they have been proposed as fillers to reinforce the mechanical properties of polymers and ceramics, 7,8 as catalyst supports for metal nanoparticles (NPs), 9 or as nanovectors for various drugs. 4,6,10 Depending on the preparation and purification methods used, the surface of NDs can be terminated by a variety of functional groups, including carboxylic groups, hydroxyls, ketones, and lactone moieties. 5,11−14 To attain the targeted properties, the surface of nanodiamonds most often needs to be functionalized, so that the interactions between the NPs and their environment are optimal. Several methods have been proposed to tune the surface properties of NDs by covalent grafting of organic moieties. 14−20To date, the characterization of NDs functionalized by organic fragments has involved a variety of methods, such as X-ray photoelectron, 21 UV, 22 and FTIR 16,20,23−26 spectroscopies. Solid-state NMR spectroscopy has been attempted, 27−29 but the use of this technique is still limited despite the high specific surface area of NDs (∼150−300 m 2 ·g −1 ), which should be favorable for detecting the surface functional groups. So far, solidstate NMR studies of NDs have mainly focused on the investigation of the core and surface structure of N...

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“…By comparing with Fig. 3a, the DNP enhancement factor E of diamond films A is estimated to be 65, which is much smaller than that of the natural diamond and the synthetic diamond we obtained before [11,12].…”

Section: Resultsmentioning

confidence: 99%

Study of diamond film by dynamic nuclear polarization-enhanced13C nuclear magnetic resonance spectroscopy

et al. 2005

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Three chemical vapor deposited diamond films were studied by dynamic nuclear polarization (DNP)-enhanced high-resolution solid-state ~~C nuclear magnetic resonance (NMR) spectroscopy. Enhanced ~3C direct-polarization speetra of diamond filrns were obtained by irradiating the samples with microwaves at or near electron spin resonance Larmor frequency of carbon center free radicals. No NMR signal for sp 2 hybridized carbons could be observed. From the curve of the DNP enhancementas a function of frequency, it is found that the dominant DNP mechanism is the solid-state effect. The ~3C cross-polarization spectrum, which is an evidence for existence of the proton defect in the lattice of diamond films, is much broader than the ~3C single pulse spectrum. The reason is discussed shortly.

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Study of synthetic diamonds by dynamic nuclear polarization-enhanced13C nuclear magnetic resonance spectroscopy

Cited by 7 publications

References 15 publications

Dynamic Nuclear Polarization for Sensitivity Enhancement in Biomolecular Solid-State NMR

Dynamic Nuclear Polarization for Sensitivity Enhancement in Biomolecular Solid-State NMR

NMR and EPR Characterization of Functionalized Nanodiamonds

Study of diamond film by dynamic nuclear polarization-enhanced13C nuclear magnetic resonance spectroscopy

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