In this work the X-Ray diffraction study of fluorine-functionalized thiosemicarbazone ligands and their corresponding cyclometallated compounds is discussed. The results are in agreement with previous characterization by IR spectroscopy, ¹H and ¹⁹F NMR spectroscopies.

Suitable crystals were obtained for a thiosemicarbazone ligand and a cyclometallated compound. The crystal structure analyses are in accordance with the proposed structures: a thiosemicarbazone ligand fluorine-functionalized and a cyclometallated compound in which the thiosemicarbazone is a tridentate [C, N, S] donor ligand. A comparative study of bond distances and angles is shown, providing information about the coordination of the ligand to the metal center.

Methanocaldococcus jannaschii, a hyperthermophilic and barophilic methanarchaeon, contains a single gene (MJ0285) encoding a 16.5-kDa polypeptide chain of a small heat-shock protein (sHSP). This sHSP—now called MjsHSP16.5—is upregulated in response to high growth temperature or pressure (1, 2) and functions as a broad substrate ATP-independent holding chaperone that transiently binds and prevents the misfolded proteins from aggregation (3-7). Despite being extensively studied for decades, the molecular mechanism of MjsHSP16.5 is still remained to be elucidated, which primarily required a higher resolution of MjsHSP16.5 structure. In this study, using the single-particle cryo-electron microscopy (cryo-EM) technique which has the capacity in achieving near-atomic resolution of macromolecular structures and preserving the macromolecular shapes in solution, we reconstructed the MjsHSP16.5 24-subunit oligomer to a 2.5-Å resolution. Despite a similar hollow spherical homo-oligomer, the MjsHSP16.5 cryo-EM structure is slightly bigger than its crystal structure and reveals a loosen subunit-subunit interactions. Furthermore, cryo-EM image reconstruction shows additional N-terminal residues which are absent in most of MjsHSP16.5 crystal structures. These residues likely involve the holding chaperone activity and the oligomer stabilization. Using dynamic light scattering (DLS) and negative-staining transmission electron microscopy (TEM), we observed that MjsHSP16.5 oligomer was shrunk upon heating, suggesting a large conformational change in MjsHSP16.5 at elevated temperature. To our knowledge, MjsHSP16.5 is the first sHSP to have the cryo-EM structure archiving a resolution at 2.5 Å.

1) BB Boonyaratanakornkit et al. Environmental Microbiology. 2005. 7(6), 789-797
2) BB Boonyaratanakornkit et al. Extremophiles. 2007. 11, 495–503
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4) R Kim et al. PNAS. 2003. 100(14), 8151-8155
5) A Cao et al. Biochimica et Biophysica Acta. 2008. 1784, 489–495
6) RA Quinlan et al. Phil Trans R Soc B. 2013. 368: 20120327
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Perovskite solar cells are expected to be the next generation solar cells due to their low cost and easy fabrication process. The purpose of this study is to investigate the effects of co-addition of copper, sodium and ethylammonium (EA) to the CH₃NH₃PbI₃ perovskite compound. The conversion efficiencies were enhanced by the addition of copper and sodium to CH₃NH₃PbI₃. From the first-principles calculations of the band structures, the formation of a shallow band of copper d-orbitals, which functions as an acceptor level, would promote the carrier generation. The additional excitation process from copper d-orbitals to sodium s-orbitals would suppress the carrier recombination, thus improving the conversion efficiency. Furthermore, the stability of the crystals increased by the EA substitution at the CH₃NH₃ site from the results of the total energy calculations, which would lead to suppression of formation of lattice defects. The further addition of EA also improved the conversion efficiencies, which indicates the EA substitution would stabilize the crystal structure even in the presence of copper and sodium.

Crystalline form of proteins has great advantages for different industries such as pharmaceuticals, which also has a high demand of specific crystals size with narrow distribution. This is challenging due to the inherent difficulty of having reproducible, controllable, and profitable processes. The easiest way to control crystalline polydispersity is by directing the crystallization process. Nucleation, as the first stage of the process, predetermines the final number of crystals and control their size but difficult to control due to its stochastic nature. Therefore, overcoming the nucleation step seems the simple way to tune the final product. Seeding in a metastable solution seems the simple way to do it.

Hydrogels have demonstrated their ability to produce higher quality crystals, influencing nucleation and growth, while providing a non-convection medium. Thus, using the gelled batch method as a means of crystallization seems as a good option due to its simplicity and its ability to be scalable.

Still gelling a crystallizable protein metastable solution introduce a new set of variables to be adjusted in order to: properly compartment the space (gel homogeneity, etc.), control the influence of the gel of the crystallization and seed stability, etc. In this work we present the preliminary results of our strategy to control the homogeneity and final size of the lysozyme crystals by means of agarose batch seeding. Our preliminary results clearly show that there is a direct correlation between the initial size of the seeds and the final size of the crystals, maintaining a narrow size distribution.^1–4

References:

(1) Nanev, C. N. Crystal Size Distribution Resulting from the Time Dependence of Crystal Nucleation.Cryst.Res.Technol.2018,53(5),1700248. https://doi.org/10.1002/crat.201700248.

(2) Pu, S.; Hadinoto, K. Continuous Crystallization as a Downstream Processing Step of Pharmaceutical Proteins: A Review. Chem. Eng. Res. Des. 2020, 160, 89–104. https://doi.org/10.1016/j.cherd.2020.05.004.

(3) Gavira, J. A. Current Trends in Protein Crystallization. Arch. Biochem. Biophys. 2016, 602, 3–11. https://doi.org/10.1016/j.abb.2015.12.010.

(4) Contreras-Montoya, R.; Arredondo-Amador, M.; Escolano-Casado, G.; Mañas-Torres, M. C.; González, M.; Conejero-Muriel, M.; Bhatia, V.; Díaz-Mochón, J. J.; Martínez-Augustin, O.; Sánchez de Medina, F.; Lopez-Lopez, M. T.; Conejero-Lara, F.; Gavira, J. A.; Álvarez De Cienfuegos, L. PAGE PENDING_Insulin Crystals Grown in Short-Peptide Supramolecular Hydrogels Show Enhanced Thermal Stability and Slower Release Profile. ACS Appl. Mater. Interfaces 2021. https://doi.org/10.1021/acsami.1c00639.

Over the last decade, continuous manufacturing techniques have been widely used in pharmaceutical manufacturing industries. However, despite the outstanding performance associated with the steady-state operation, continuous processes face common and important challenges of low efficiency and material waste during the start-up and shutdown. Considering that most pharmaceutical manufacturing is accomplished in a short operation window, an ideal start-up and shut down strategy will have a significant impact on the economic and environmental performance of the continuous pharmaceutical process. In this study, a combined start-up, steady-state, and shutdown optimization of a three-stage mixed suspension mixed product removal (MSMPR) crystallizer was compared against optimized batch and fed-batch crystallizers. The crystallization of aspirin (acetylsalicylic acid, ASA) in ethanol (solvent) and water (antisolvent) was used as a case study. The optimization problems were solved using a hybrid method, which combines a genetic algorithm and a sequential quadratic programming (SQP) method. The multistage continuous crystallizer was designed and optimized to maximize on-spec production over a total operating window of 800 min. It was shown that a max on-spec production of 5858 g can be achieved with the continuous process. A batch and a fed-batch crystallizer were designed and optimized to achieve the same production rate and help establish a reliable basis for rigorous technoeconomic analysis and comparison.