The resolution of magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra remains bounded by the spinning frequency, which is limited by the material strength of MAS rotors. Since diamond is capable of withstanding 1.5-2.5x greater MAS frequencies, compared to state-of-the art zirconia, we fabricated rotors from single crystal diamond. When combined with bearings optimized for spinning with helium gas, diamond rotors could achieve the highest MAS frequencies to date. Furthermore, the excellent microwave transmission properties and thermal conductivity of diamond could improve sensitivity enhancements in dynamic nuclear polarization (DNP) experiments. The fabrication protocol we report involves novel laser micromachining and produced rotors that presently spin at ω/2π = 111.000 ± 0.004 kHz, with stable spinning up to 124 kHz, using N gas as the driving fluid. We present the first proton-detected C/N MAS spectra recorded using diamond rotors, a critical step towards studying currently inaccessible ex-vivo protein samples with MAS NMR. Previously, the high aspect ratio of MAS rotors (∼10:1) precluded fabrication of MAS rotors from diamond.
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http://dx.doi.org/10.1016/j.jmr.2023.107475 | DOI Listing |
J Phys Chem Lett
November 2024
Department of Chemistry and Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Substitutional nitrogen impurities within the diamond lattice, known as P1 centers, have unpaired electrons that can mediate microwave driven dynamic nuclear polarization (DNP). In this paper we explore DNP of the bulk C spins in micrometer-sized P1 diamond particles and demonstrate a 550-fold DNP enhancement of the bulk C spins at room temperature in a 9 T magnetic field or 250 GHz for ≈ 2 electrons. We study the DNP mechanisms, exploring their dependence on sample spinning frequency and microwave irradiation frequency using both continuous wave and frequency swept microwave irradiation, and discuss the results alongside recent DNP studies in the literature.
View Article and Find Full Text PDFAnal Chem
January 2024
School of Chemical Engineering and Technology, Xi'an Jiaotong University, 28 Xianning West Road, Xi'an, Shaanxi 710049, P.R. China.
Microfluidic paper-based analytical devices (μPADs) feature an economic and sensitive nature, while acoustofluidics displays contactless and versatile virtue, and both of them gained tremendous interest in the past decades. Integrating μPADs with acoustofluidic techniques provides great potential to overcome the inherent shortcomings and make appealing achievements. Here, we present acoustofluidics-assisted multifunctional paper-based analytical devices that leverage bulk acoustic waves to realize multiple applications on paper substrates, including uniform colorimetric detection, microparticle/cell enrichment, fluorescence amplification, homogeneous mixing, and nanomaterial synthesis.
View Article and Find Full Text PDFAnal Chem
August 2023
Department of Chemistry and COSDAF (Centre of Super-Diamond and Advanced Films), City University of Hong Kong, 83 Tat Chee Avenue, Kowloon 999077, Hong Kong, China.
Organelle-targeted photosensitizers (PSs) have demonstrated enhanced phototherapeutic effect by specifically destroying subcellular organelle. As a critical cellular organelle, the cell membrane plays crucial roles in maintaining cell integrity and regulating cellular communications. To date, a variety of membrane-targeted PSs have been developed and shown exceptional therapeutic effects.
View Article and Find Full Text PDFOrg Lett
August 2023
Department of Materials Science and Engineering, Department of Chemistry, and Center Of Super-Diamond and Advanced Films (COSDAF), City University of Hong Kong, 83 Tat Chee Avenue, Hong Kong, SAR 999077, P. R. China.
Three "π"-shaped D-A-type thiodiazoloquinoxaline derivatives with different electronic structures and rotations have been prepared. Their particular structures allow these molecules to possess a broad absorption range and sufficient intramolecular motions, dissipating energy through a thermal deactivation pathway. Among the three materials, showed the best steam generation efficiency (84.
View Article and Find Full Text PDFJ Magn Reson
July 2023
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, MA 02139, USA; Francis Bitter Magnet Laboratory, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. Electronic address:
The resolution of magic angle spinning (MAS) nuclear magnetic resonance (NMR) spectra remains bounded by the spinning frequency, which is limited by the material strength of MAS rotors. Since diamond is capable of withstanding 1.5-2.
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