Department of Pharmaceutical Chemistry, University of Kansas, 2095 Constant Avenue, Lawrence, 66047, USA.
Published: July 2006
AI Article Synopsis
Article Abstract
Solid-state nuclear magnetic resonance spectroscopy (SSNMR) line widths were measured for various ibuprofen preparations, including crystallization from different solvents (acetone, acetonitrile, methanol), melt-quenching, manual grinding, cryogrinding, compacting, and by blending with various excipients. Ibuprofen recrystallized from acetonitrile exhibited broader lines than ibuprofen recrystallized from either acetone or methanol. Manually ground ibuprofen had SSNMR line widths that were indistinguishable from the commercial sample, but cryoground ibuprofen had larger line widths than either. Physical mixtures with most excipients decreased the SSNMR line widths. Only dilution in talc led to line width increases, which is attributed to the magnetic susceptibility anisotropy of the talc excipient. Our results show that SSNMR line widths can be used to understand physical characteristics including particle size and morphology, degree of order in the materials, and physical environment.
Shenzhen Key Laboratory of Ultraintense Laser and Advanced Material Technology, Center for Intense Laser Application Technology, and College of Engineering Physics, Shenzhen Technology University, Shenzhen, China.
This study employed multifractal analysis to investigate the changes in surface morphology of SiO anti-reflective coatings prepared on KDP substrates using the sol-gel method, under various conditions of ultraviolet (UV) irradiance. The coatings were successfully fabricated, and the chemical structure of the SiO sol was comprehensively characterized using Solid-State Nuclear Magnetic Resonance (SSNMR) technology. Under low UV irradiance (4 J/cm), repeated experiments revealed a crack-induced mechanism of surface fatigue damage.
The eggshell is a composite and highly ordered structure formed by biomineralization. Besides other functions, it has a vital and intricate role in the protection of an embryo from various potentially harsh environmental conditions. Solid-state nuclear magnetic resonance (SSNMR) has been used for detailed structural investigations of the chicken, tinamou, and flamingo eggshell materials.
Magic-angle spinning (MAS) solid-state NMR methods are crucial in many areas of biology and materials science. Conventional probe designs have often been specified with 0.1 part per million (ppm) or 100 part per billion (ppb) magnetic field resolution, which is a limitation for many modern scientific applications.
NMR chemical shifts provide a sensitive probe of protein structure and dynamics but remain challenging to predict and interpret. We examine the effect of protein conformational distributions on N chemical shifts for dihydrofolate reductase (DHFR), comparing QM/MM predicted shifts with experimental shifts in solution as well as frozen distributions. Representative snapshots from MD trajectories exhibit variation in predicted N chemical shifts of up to 25 ppm.
Laboratory of Chemical Physics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, Bethesda, Maryland 20892-0520, United States.
Polypeptides often self-assemble to form amyloid fibrils, which contain cross-β structural motifs and are typically 5-15 nm in width and micrometers in length. In many cases, short segments of longer amyloid-forming protein or peptide sequences also form cross-β assemblies but with distinctive ribbon-like morphologies that are characterized by a well-defined thickness (on the order of 5 nm) in one lateral dimension and a variable width (typically 10-100 nm) in the other. Here, we use a novel combination of data from solid-state nuclear magnetic resonance (ssNMR), dark-field transmission electron microscopy (TEM), atomic force microscopy (AFM), and cryogenic electron microscopy (cryoEM) to investigate the structures within amyloid ribbons formed by residues 14-23 and residues 11-25 of the Alzheimer's disease-associated amyloid-β peptide (Aβ and Aβ).
