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Nanocarrier Technologies for Enhancing the Solubility and Dissolution Rate of Api
Published in Debarshi Kar Mahapatra, Sanjay Kumar Bharti, Medicinal Chemistry with Pharmaceutical Product Development, 2019
Ashwini Deshpande, Tulshidas S. Patil
Crystallography: Any possible fluctuations in the physical form of the drug brought about during nanoparticle processing are determined by either X-ray diffraction, Differential scanning calorimetry or other analytical methods. Neutron diffraction is a technique used to carry out the crystallography studies of simple lattice structures. Its use can also be extended to crystalline organic solids, except that the data analysis of such samples is much more challenging.
Because Something Unexpected Happens
Published in John R. Helliwell, The Whys of a Scientific Life, 2018
I set about collaborating with the scientists at the nuclear research reactor in Grenoble, for which the United Kingdom had a one-third share, to undertake the neutron diffraction data collection. Neutrons have a second very important property, besides allowing clearer visualisation of deuterium atoms: They do not cause radiation damage to the sample. In the late 1980s, I published a paper on the specific X-ray damage causing the splitting of the disulphide covalent bond in a protein [2]. Here, then, with neutrons, was a way of avoiding such X-ray damage. A further aspect was that research that I had been doing using the polychromatic X-ray emission from the synchrotron also could be applied to the neutron reactor emission of neutrons. This approach would increase the effectiveness of the use of the reactor's neutrons and in fact reduce the need for such large-volume crystals. A highly effective collaboration developed between my laboratory in Manchester and the scientists in Grenoble. In fact, the applications to many other proteins of such neutron diffraction studies are ongoing, and a former PhD student of mine, Dr Matthew Blakeley, is in charge of two of the Laue diffractometer (LADI) instruments, LADI-A and LADI-B. A new neutron source, the European Spallation Source, is also now under construction in Lund, Sweden. I am chair of the Neutron Macromolecular Crystallography Scientific and Technical Advisory Panel.
Chromatin Structure and Gene Regulation
Published in M. Gerald, M.D. Kolodny, Eukaryotic Gene Regulation, 2018
The compression of DNA within the chromosome is many times greater than within the nucleosome, and therefore, higher orders of structure must exist. Thick chromatin fibers 200 to 300 A in diameter appear to be formed by coiling monofilaments of nucleosomes into a solenoid structure. Finch and Klug43 examined, by electron microscopy, chromatin prepared in such a way as to preserve its superstructure. They suggest that the monofilament coils to form a solenoid with six nucleosomes per turn. The solenoid appears to require histone HI for its stabilization. Neutron diffraction studies of Carpenter et al.21 also report the existence of solenoid structures.
Electron microscopy overview of SARS-COV2 and its clinical impact
Published in Ultrastructural Pathology, 2022
Soheir Saiid Mansy, Mona Mahmoud AbouSamra
Many techniques, including NMR spectroscopy, X-ray solution scattering, neutron diffraction, various spectroscopic techniques, and X-ray crystallography, have been used to determine the shape and structure of biological molecules. Recently, cryo-electron microscopy has become the most effective tool in structural biology after the technical development of its resolutions, which permits the identification of the biomolecular structure in its natural state.59 Cryo-EM has an advantage over X-ray crystallography, and is the most effective tool in analyzing macromolecules during the last few years. Cryo-EM reveals structures in fast-frozen non-crystalline biological samples that are closer to their natural state at an atomic level. In addition, it requires much smaller macromolecule samples to work with, unlike X-ray crystallography, which needs large pieces of materials to optimize the crystallization conditions.59 Hence, cryo-EM has become the tool of choice for determining the structure of macromolecular complexes, especially supra-assemblies that are difficult to prepare in large quantities or virtually inaccessible to crystallize.59,61,62 Identifying the structural biology of viral protein complexes at molecular resolution is important for designing small drug molecules to bind and impair their function.32
Loading, release profile and accelerated stability assessment of monoterpenes-loaded solid lipid nanoparticles (SLN)
Published in Pharmaceutical Development and Technology, 2020
Aleksandra Zielińska, Nuno R. Ferreira, Agnieszka Feliczak-Guzik, Izabela Nowak, Eliana B. Souto
Because of the possibility for the organization of alkane chains into different packing patterns: α (hexagonal – the most disordered), β´(orthorhombic) and β (triclinic – the most organized), lipids can occur in different polymorphic forms (Allais et al. 2003; Beck et al. 2011). Furthermore, the polymorphic structure may directly influence on the encapsulation efficiency and expulsion of the drug during storage (Beck et al. 2011). Therefore, it is necessary to detect the possible existence of the polymorphism before the introduction of SLN in the industry. In this work, X-ray diffraction (XRD) analysis was applied to determine the structure on the SLN dispersions, composed by the solid lipid, drug, surfactant and dispersion medium. Two XRD techniques, for which the main difference is the range of scattering angles 2θ (Westesen et al. 1993; Allais et al. 2003), have been applied, namely small angle X-ray scattering (SAXS) and small angle neutron scattering (SANS), and wide angle X-ray scattering (WAXS) and neutron diffraction (ND). Both of methods detect electron (X-ray scattering) and nucleus (neutron scattering) density fluctuations, respectively, on a length scale d according to Bragg’s law: 2d sin θ = λ (Bunjes and Unruh 2007).
Insight of the various in silico screening techniques developed for assortment of cocrystal formers and their thermodynamic characterization
Published in Drug Development and Industrial Pharmacy, 2021
Parth Sarathi, Swarupanjali Padhi
Development of CSD have significant contribution in various areas viz. drug discovery and development, structural chemistry, material science, and life science. Olga Kennard (Founder of Cambridge Crystallographic Data Center) and his colleagues started collecting the published bibliographic, chemical and crystal structure data of all small molecules studied by X-ray and neutron diffraction, further with the advent of algorithmic process and software these data were encoded into electronic form, leading to the development of CSD. Groom and his colleagues further added large number of structures to this database. CSD also facilitate the evaluating crystal and inter-molecular interactions. Approximately 40,000 new structures are added every year from journals or supplementary papers. CSD software has been regularly revised and carefully reviewed for errors and scientific integrity. The CSD can be used to forecast stable hydrogen bonding motifs to keep most robust motifs intact across the families of similar structure [17,18]. An inorganic structure which does not fit in criteria above is added to an inorganic crystal structure database [19] produced by the metal database [20] for metal and alloys. CSD also includes peptides, polysaccharides of up to 24 residues and mono, di, and trinucleotides, higher oligomers are covered by the Nucleic Acid Database [21] along with Protein Data Bank (PDB) [22]. CSD stored information for each entry can be classified into three classes. The first class consists of text-based information which may also include numeric in certain cases; catalog viz. list of reference, chemical name, and molecular formula, some experimental information about the procedure used in the determination of crystal structure and other information related to color, shape, and use of crystals, etc. The second line consists of chemical correspondence information in the form of a 2-D structural diagram, which is used for searching sophisticated methods form CSD systems. The third line includes crystallographic data, consisting of unit cell dimension, atomic collaboration, and space group, where the true value of data exists [23]. From the data of CSD, a network approach tool has been developed for the prediction of co-crystallization which consists of analyses of molecular descriptor, molecular modeling [24], H-bond propensity calculation [25] and molecular electrostatic potential surface [26] (Table 1).