Crystal Structure Research Articles

In-silico Studies of Some Novel Pyrazoline Derivatives Focusing on Melanoma, Antimicrobial and Anti-inflammatory Activity

Microbial infections often produce pain and chronic inflammation, leading cause of cancer. The compound possessing anti-cancer potency with wide spectrum anti-microbial and anti-inflammatory activity is not common. Study focuses on designing a series of novel pyrazoline derivatives active towards anti-neoplastic, anti-microbial and anti-inflammatory response. The pyrazoline derivatives were investigated against the structure of vanin-1: defining the link between metabolic disease, oxidative stress and inflammation and Crystal structure of antigen 43 from uropathogenic Escherichia coli UTI89. Furthermore, the antitumor activity of pyrazoline compounds was evaluated against the crystal structure of human melanoma-associated antigen B1 (MAGEB1). The reported data highlight the impact of chemical structure variations on biological activity. Specific structural modifications consistently altered activity across all tests. Introducing p-nitro and p-hydroxy groups into the aryl moiety of the pyrazoline analogs resulted in compounds with significant anti-inflammatory, antimicrobial, and anticancer properties. The enhanced activities are attributed to the presence of 4-NO₂, 4-OH, and 4-Cl groups in the phenyl ring at the 5-position of the pyrazoline ring. In certain cases, these compounds demonstrated activities equal to or exceeding those of standard drugs.

Fabrication of N,C-H2TiO3 Ion Sieves for Rapid Adsorption of Lithium Using Rheological Phase Methods

Modifying β-H2TiO3 by elemental doping improves its adsorption capacity and shortens the equilibrium adsorption time, which is of positive significance for its industrial application.Herein, a novel N, C co-doped Li2TiO3 lithium ion sieve precursor N,C-Li2TiO3-3 (noted as N,C-LTO-3) was successfully prepared via the rheological phase method using urea as a vital raw material. Crystal structure of N,C-LTO-3 was characterized via XRD, XPS, FT-IR, and Raman. The morphology of N,C-LTO-3 was analysed by SEM and HR-TEM. The N,C-LTO-3 was pickled and obtained to N,C-H2TiO3-3, namely N,C-HTO-3. The equilibrium adsorption capacity (Qe) of N,C-HTO-3 was as high as 40.6mg⋅g-1 in LiOH solution of 100mg·L-1 at 293K. Ti4+ dissolution loss rate is below 0.5% in the fifth cycle. Adsorption isothermal curve, kinetics, and thermodynamic behaviour were fitted with the according equations. The exchange energy of N,C-HTO-3 for Li+ was calculated by density functional theory (DFT) to assess the feasibility of lithium absorption. Furthermore, N,C-HTO-3 exhibited high regeneration and selectivity for Li+ in lithium-containing brine, making N,C-HTO-3 an ideal candidate for Li+ extraction.

Synthesis, single crystal investigations, DFT studies, biological activities, DNA cytotoxicity and molecular docking studies of copper(II) complex derived from the new o-vanillin Schiff base ligand

A novel Schiff base derivative, (E)-N’-(2-hydroxy-3-methoxybenzylidene)-2-phenylacetohydrazide (HMPH, H2L), and its Cu(II) complex were synthesized through the direct condensation of o-vanillin with phenylacetichydrazide in ethanol under reflux conditions. The synthesized ligand was identified usingelemental analysis, Fourier transform infrared (FTIR) and ultraviolet–visible (UV–Vis.) spectroscopy. The structures of HMPH (C16H16N2O3)2 and its Cu(II) complex [Cu(L)(H2O)]·H2O (C16H16N2CuO4·H2O) were analysed by single crystal X-ray diffraction technique. The X-ray diffraction results showed that HMPH crystallised in an orthorhombic Pca21 space group with a Z value of 8, while [Cu(L)(H2O)]·H2O crystallised in a monoclinic C 2/c space group with the same z value. The Cu(II) ion is coordinated to the acetohydrazide ligands via hydrazone nitrogen, aceto oxygen (N(2) and O(1)) and hydroxyl O(2) atoms. In addition to the single crystal structures of HMPH and [Cu(L)(H2O)]·H2O, the optimised molecular structures, molecular electrostatic potential meps, molecular orbital energy values, and interactions between DNA bases and molecular structures are determined by DFT/B3LYP/6-311G(d, p) for HMPH and DFT/B3LYP/LanL2DZ for [Cu(L)(H2O)]·H2O. The copper complex was found to be more potent than the organic ligand in terms of antimicrobial activity, with a strong anti-biofilm effect even at low MIC values. The cytotoxicity of the synthesized compounds was investigated on MDA-MB-231 cell lines. The [Cu(L)(H2O)]·H2O complex was found to be more lethal than the HMPH ligand. Furthermore, molecular docking studies of HMPH and [Cu(L)(H2O)]·H2O with P. aeruginosa ATCC27853 (PDB ID: 6P8U) were presented to explain the observed antibacterial activity and the mechanism-of-action.

Synthesis and structural studies of ammonium exchanged synthetic analogue of disordered aluminosilicate natrolite

The current article reports preparation and structural analysis of NH4+ exchanged form of synthetic natrolite zeolite (NH4-natrolite) with disordered structure wherein Si and Al occupies all the tetrahedral (T) sites in the zeolite framework. Structural data is used to gain insight into the structural parameters those influence thermal stability of its proposed H-form. NH4-natrolite is prepared by ion-exchange method from K-natrolite (which was also obtained by ion-exchange with Na-natrolite). Na-natrolite, K-natrolite and NH4-natrolite prepared in this study were tested for their structural, morphological and thermal analysis. Synchrotron x-ray diffraction data was utilized to estimate the crystal structures of hydrated forms of Na-natrolite, K-natrolite and NH4-exchanged natrolites. Thermal analysis of NH4-natrolite revealed that the dehydration is followed by removal of ammonia during calcination. The role of the size (radius) and nature (either divalent or monovalent) of the exchangeable cations present in the channels, the framework chemical content and extent of ‘T’ atom ordering have been collectively discussed and correlated with the structural behaviour of calcined NH4-natrolite to explain its thermal stability in better way.

Artificial trimerization of β-glucosidase for enhanced thermostability and activity via computational redesign

The improvement of enzyme thermostability is of great significance in the biotechnology industry. Herein, we modified the C-terminus of β-glucosidase via the computer-aided rational design and successfully obtained six variants that exhibit improved optimal temperatures and thermal inactivation half-lives at 65 °C. Among these variants, the thermal inactivation half-life and hydrolytic activity of TrCel1b-H13 at 65 °C were increased by 416 and 3223 folds, respectively, compared to those of the wild type. The optimal catalytic temperature and melting temperature (Tm) of TrCel1b-H13 were elevated by 55 °C and 20 °C respectively, compared to those of the wild type. The Kcat/Km value of TrCel1b-H13 was improved by 13.3-fold, compared to that of the wild type. Furthermore, we found that the modified β-glucosidase, TrCel1b-H13, self-assembles into a trimeric structure, which was confirmed by X-ray crystallography and blue native polyacrylamide gel electrophoresis. The amino acid residues, including E28, H60, E99, K106, and K471, located at the trimeric interface of the adjacent subunits, were found to play an important role in maintaining the crystal structure of the protein trimer. Thus, protein multimerization via the computer-aided rational design method provides a cost-effective tool for simultaneously improving the thermostability and activity of enzymes.

Effect of heat treatment on microstructure and mechanical properties of WE43 alloy fabricated by wire arc additive manufacturing

Heat treatment is an effective method to improve the mechanical properties of Wire Arc Additive Manufacturing (WAAM) WE43 alloy. This study investigates the effects of heat treatment on the microstructure and mechanical properties of the WE43 alloy processed by WAAM. The as-deposited samples exhibit a uniform equiaxed crystal structure, with grain size gradually increasing as the number of deposited layers grows. The as-deposited microstructure comprises eutectics and a small amount of cubic phases, and the phase content escalates as the amount of deposited layers increases, influenced by the cumulative effect of multiple thermal cycles. At lower solid solution temperatures (480 ℃ × 8h), most of the eutectic phase remains undissolved. During tensile testing, undissolved eutectics tend to cause stress concentrations, leading to cracks that result in sample fractures, negatively affecting the mechanical properties. At higher solid solution temperatures (520 ℃ × 8h), most of the eutectic dissolves, but abnormal grain coarsening (AGC) in the interlayer fine-grain region occurs, causing a significant reduction in the sample's mechanical properties. After solid solution treatment at 500 °C for 8hours, only a small amount of eutectics remains undissolved, and the AGC phenomenon is not observed, resulting in an optimal solid solution effect. Subsequently, after aging treatment at 225 °C for 18hours, dense nanoscale β′′ phases precipitated within the alloy grains, significantly improving the mechanical properties. The samples achieved optimal performance, with UTS, YS, and EL of 323±15.2MPa, 225±11.3MPa, and 8.4±1.1%, respectively.

A DFT-based computational study on a highly and lead-free inorganic new fluoroperovskite of Mg3PF3

Inorganic fluoroperovskite materials are increasingly important in solar technology due to their exceptional structural, optical, electronic, and mechanical properties. This study uses DFT calculations to investigate the properties of Mg3PF3 fluoroperovskite. Our results show a crystal structure and lattice parameter of (a = 4.64 Å) which align with previous theoretical and experimental findings, confirming the accuracy of our calculations. Mechanical analysis reveals that Mg3PF3 is naturally ductile, elastically anisotropic, and stable according to established criteria. The band structure and PDOS indicate that it is a semiconductor with direct bandgap of 3.88 eV at the Γ point, making it suitable for electronic applications. Electron charge density mapping suggests a predominantly ionic bonding nature. Optical property analysis shows significant dielectric constant peaks in the photon energy range favorable for solar cells. Overall, these findings position Mg3PF3 as a promising candidate for solar cell technology, highlighting its potential for enhancing renewable energy solutions.

Identification of Key Post‐modification Enzymes Involved in the Biosynthesis of Lanostane‐type Triterpenoids in the Medicinal Mushroom Antrodia camphorata

Lanostane‐type triterpenoids are important bioactive secondary metabolites of mushrooms, though their biosynthetic study has been challenging due to scattered genes. Herein, the strategies of combining metabolomics and transcriptomics analyses, functional motif blast, and KEGG (Kyoto Encyclopedia of Genes and Genomes) annotation were used to discover three key post‐modification enzymes involved in the biosynthesis of lanostanoids in the medicinal mushroom Antrodia camphorata. The cytochrome P450 enzyme AcCYP4 could generate a Δ7,9(11) diene structure and introduce a 15α‐hydroxy group to the triterpene skeleton. The short‐chain dehydrogenase AcSDR6 could regio‐ and stereo‐ selectively catalyze the dehydrogenation of 3β‐OH to produce 3‐keto triterpenoids, and the catalytic mechanisms were interpreted by crystal structure analysis. AcSMT1 could introduce the methyl group at C‐24 to produce a unique 31‐carbon triterpene skeleton. This work elucidated the major biosynthetic pathway of Antrodia lanostanoids in vitro, and the discovered enzymes could be used to synthesize a series of bioactive triterpenoids.

The seventh blind test highlights exciting developments in crystal structure prediction.

Two reports on the seventh blind test on crystal structure prediction extensively discuss the cutting-edge avant-garde methods of structure generation and energy ranking.

Revolutionizing Antiviral Therapeutics: In silico Approaches for Emerging and Neglected RNA Viruses.

The 21st century has shown us how rapidly the pandemic can evolve and devastate the life of human beings without differentiating between the continents. Even after the global investment of billions of dollars into the healthcare sector, we are still lacking multiple therapeutics against emerging viruses. World Health Organization (WHO) has listed a number of viruses that could take the form of pandemics at anytime, depending upon their mutations. Among those listed, the SARS-CoV, Ebola, Zika, Nipah, and Chikungunya virus (CHIKV) are the most known viruses in terms of their number of outbreaks. The common feature among these viruses is their RNA-based genome. Developing a new therapeutic candidate for these RNA viruses in a short period of time is challenging. In silico drug designing techniques offer a simple solution to these problems by implementing supercomputers and complicated algorithms that can evaluate the inhibition activity of proposed synthetic compounds without actually doing the bioassays. A vast collection of protein crystal structures and the data on binding affinity are useful tools in this process. Taking this into account, we have summarized the in silico based therapeutic advances against SARS-CoV, Ebola, Zika, Nipah, and CHIKV viruses by encapsulating state-of-art research articles into different sections. Specifically, we have shown that computer- aided drug design (CADD) derived synthetic molecules are the pillars of upcoming therapeutic strategies against emerging and neglected viruses.

SnO2-TiO2/reduced graphene oxide nanocomposites: Green synthesis and enhanced photocatalytic efficiency for dye removal

Titanium oxide nanoparticles (TiO2 NPs) have been interested in potential applications, including gas-sensing, energy storage, environmental remediation, and medical fields. In the present work, fabricated SnO2-TiO2/RGO nanocomposites (NCs) have been produced through a green precipitation approach. XRD, TEM, SEM, EDX, XPS, FTIR, UV, and PL analyses have been carefully applied to invistage the physicochemical properties of prepared NPs and NCs. The XRD data showed that the crystal structure of the TiO2 NPs was affected by the introduction of SnO2 NPs and RGO sheets. The spherical shape of the prepared samples and their morphologies were confirmed using TEM and SEM images. EDX and XPS analyses confirmed that tin (Sn), titanium (Ti), oxygen (O), and carbon (C) were further present in the SnO2-TiO2/RGO NCs. FT-IR spectra determines the functional groups with bands between the compositions of obtained NPs and NCs. Besides, the band gap energies of prepares samples were estimated from UV–vis spectra. It displayed that the absorption peak of the synthesized TiO2 NPs was improved after the addition of SnO2 NPs and an RGO sheet. PL analysis indicate that the PL intensity of the prepared TiO2 NPs was decreased with the addition of SnO2 NPs and RGO sheets due to a decrease in the recombination rate of electrons (e−)-holes (h+). As shown in photocatalytic results, the photodegradation of methylene blue (MB) dye of SnO2-TiO2/RGO NCs was reached 92.20% after 140 min of UV irradiation. These results suggest that the addition of RGO sheets occupied a role in enhanced the photocatalytic performance of the prepared NCs. This study highlighted that these samples could be applied in various applications such as photocatalytic and therapeutic areas.

Investigations on Photodegradation and Antibacterial Activity of Mixed Oxide Nanocrystalline Materials

In this study, we synthesized cobalt-doped molybdenum supported on silica (Co/MS) nanocomposites with varying concentrations of cobalt (1, 5, 10, 15, and 20 wt%) using the sol-gel method. We investigated their physico-chemical properties, photocatalytic activity, and antimicrobial efficacy. The synthesized nanocomposites were characterized using a range of techniques, including X-ray powder diffraction (XRD) to determine crystal structure, UV-vis spectroscopy for optical properties, Fourier transform infrared spectroscopy (FT-IR) for functional group analysis, and scanning electron microscopy coupled with energy-dispersive X-ray microanalysis (SEM-EDX) for morphological and elemental composition analysis. The photocatalytic performance of these catalysts was assessed by their ability to degrade organic dyes, specifically methyl orange and methylene blue, under visible light irradiation. Our results demonstrated that the photocatalytic efficiency increased with higher cobalt content, with the 20 wt% Co/MS nanocomposite showing the highest degradation rates. Additionally, we evaluated the antibacterial activity of the nanocomposites against a range of microorganisms, including Gram-positive and Gram-negative bacteria, as well as fungal species. The 20 wt% Co/MS nanocomposite exhibited superior antimicrobial activity compared to the other samples, indicating its potential for applications in environmental remediation and antimicrobial treatments.

Effect of aged treatment on improving the performance of HVAF WC–Cr3C2–Ni coating on crystallization roller

The thermal shock resistance and high-temperature performance of WC–Cr3C2–Ni coatings on the surface of the crystallization roll after aged treatment were investigated in this study. The aging treatment at 320 ℃ for 2.5 h facilitated the diffusion of Cu element from the C17200 beryllium copper substrate toward the coating side of WC–Cr3C2–Ni coating, thereby enhancing the bonding between the coatings and substrates. After the aged treatment, the internal structure of the C17200 substrate changed from a dendritic structure to an equiaxed crystal structure, the hardness increased from 225.71 Hv0.5 to 406.52 Hv0.5 (80.4 % increased), and the wear resistance increased.Although the aging treatment reduced the hardness of the coating slightly (from 1257.58 Hv0.5 to 1155.16 Hv0.5, a decrease of 8.1%) and wear resistance (the coefficient of friction, from 0.335 to 0.312, a decrease of 6.9%). However, in the thermal shock test, the thermal shock resistance of the coating after aging treatment was increased from 19 times to 20 times (5.3% increased). However, the thermal shock failure cracks between the coatings and the substrates were transferred from the substrate part to the joint part of the two, which effectively avoided the waste of the crystallization roller substrate in the maintenance process. This research effectively reduces the purchase and maintenance costs of steel mills in actual production and provides theoretical support for cost reduction and efficiency increase in other HVAF (high-velocity air fuel) coating applications.

Enhancing strength-ductility synergy in nano-sized TiB2/Al composite via rapid solidification and thermo-mechanical processing

The Al-Cu-Mn (AA2219) composite reinforced by 5 wt% nano-sized TiB2 particles were fabricated by hot isostatic pressing (HIP) combined with thermal-mechanical processing to achieve a superior strength-ductility combination. Coupling the comprehensive characterizations and microstructure-based analysis, the strength-ductility mechanisms were deeply understood. Results reveal that the uniform dispersed nano-sized TiB2 particles under the current preparation process helps to improve the mechanical properties of the composite. The introduction of pre-stretch before artificial aging produced a fine θ' and S precipitates. By combining high-resolution TEM and crystal structure analysis, Al(Cu) and S phase at TiB2/Al interface were identified, and their mismatch (δ) with Al were 3.8 % and 4.8 %, respectively. Mechanisms related to pre-stretch effects on the formation of dislocation, θ' and S precipitates and corresponding structures are discussed, as well as the implications of TiB2/Al interface characteristics on strength and ductility.

Preparation of carboxylated-silk nanofibers by the one-pot method of maleic acid hydrolysis.

In this study, a maleic acid (MA) hydrolysis one-pot method is proposed to prepare carboxylated silk nanofibers (MA-SNFs). The MA concentration, hydrolysis temperature, and processing time were optimized. Combined with high-pressure homogenization, MA-SNFs with a carboxyl content of 0.617±0.019mmol/g and length of 333±116nm were obtained with a yield of 54.90±1.98% at the optimal conditions: 50wt% of MA concentration, 110°C of hydrolysis temperature and 120min of processing time. The morphology, chemical structure, and crystal structure of raw silk fibroin (SF), acid-hydrolyzed silk fibroin and nanofibers were studied. Furthermore, MA was reused several times with a recovery rate of >94% and maintained almost the same treatment effect. Finally, due to the presence of carboxyl groups, MA-SNF hydrogels were successfully prepared by an acetic coagulation vapor bath which exhibited excellent self-supporting ability and mechanical properties as well as a more sensitive pH response compared with regenerated silk fibroin solution and other non-carboxylated silk nanofibers. The MA-SNF aerogels had the characteristics of light weight, high strength and porous with cross-linked nanostructures.

Modifiers for the preparation of starch composites under mechanochemical activation: An extended set of criteria

Modification of starch with synthetic polymers under mechanochemical activation is a convenient way to regulate the operational properties of composite materials. The widespread use of this approach is limited by the lack of data on the influence of synthetic polymer nature on the properties of starch and the absence of clear criteria for modifiers selection in the form of aqueous dispersions. To eliminate existing problems, the work proposes to use five integral criteria − polarity, hydrophilicity, and flexibility of synthetic modifiers, as well as particle size and ζ-potential of their aqueous dispersions. To achieve this goal, we studied the dielectric constant, contact angles, IR spectra, and dynamic mechanical properties of four acrylic copolymers and an aliphatic polyurethane. Using the mechanochemical activation, blends and composite films based on corn starch and synthetic modifiers (80:20) were manufactured. Methods of rotational viscometry, X-ray diffraction analysis, DMA, mechanical tests, and moisture permeability allowed us to reveal the influence of the modifier integral parameters on the rheological characteristics of the molding blends and the impact of joint mechanical activation on them, as well as on the crystal structure of the composites, their storage modulus, strength, and transport characteristics.

Preparation and investigation of physicochemical properties of g-C3N4/LaCoO3 heterostructure for photocatalytic dye degradation

Photocatalytic decomposition of pollutant is the most optimal approach for the wastewater remediation. Nevertheless, the development of a catalyst that is both cost-effective and extraordinarily active remains a substantial challenge. The g-C3N4/LaCoO3 heterostructure were prepared by different weight percentages of g-C3N4 (15, 30, 45, 60, and 75 wt%). The g-C3N4 and LaCoO3 were exhibits hexagonal and rhombohedral crystal structure respectively. The g-C3N4/LaCoO3 heterostructure exhibits tiny particles were anchored over the coarse like structure. The g-C3N4/LaCoO3 heterostructure promote visible light harvest and inhibit charge carrier recombination than the bare LaCoO3 and g-C3N4 and which helps to enhance the organic pollutant elimination performances. The g-C3N4/LaCoO3 heterojunction exhibits superior methylene blue degradation when compared to bare LaCoO3 and g-C3N4. Furthermore, the composite of LaCoO3/g-C3N4–60 wt% exhibits higher photocatalytic activity and exceptional stability were observed under visible light irradiation.

Static solid cooling (SSC) method for directional solidification and single crystal production: A CAFE Simulation Approach

This article presents a novel directional solidification (DS) technique called static solid cooling (SSC), which has been characterized and compared to the conventional high rate solidification (HRS) method using finite element simulation and a coupled three-dimensional (3D) cellular automaton finite element (CAFE) method. The SSC technique uses alternative heat conductor and insulation layers to provide DS conditions. Simulation results show that the SSC method provides a higher cooling rate, temperature gradient, and velocity of the solidification front compared to the HRS method. Moreover, due to its higher heat dissipation ability, the SSC method produces a convex shape in the solidification front, which is crucial for the production of defect-free single crystal blades. According to the simulation model, the HRS method can produce a defect-free single crystal structure up to a withdrawal rate of 3 mm/min, whereas, the SSC method can maintain a single crystal structure without any stray grain defects up to a withdrawal rate of 6 mm/min. These findings demonstrate the effectiveness of the novel SSC technique over the conventional HRS method in producing high-quality single crystal structures. The proposed method could have significant implications for industries such as aerospace and energy that require high-performance materials with superior mechanical properties at elevated temperatures.

The OH-stretching region in infrared spectra of the apatite OH-Cl binary system

Abstract Polarized Fourier transform infrared (FTIR) microspectroscopy of the OH-stretching region of hydroxylapatite-chlorapatite solid solutions presents novel problems for the assignment of peaks to specific OH-Cl pairs. Crystal structure refinements of Hughes et al. (2016) identified new positions for column anions in synthetic mixed Cl-OH apatites, with three different column anion arrangements depending on composition. These structural refinements, combined with bond-valence calculations, allow for interpretation of the OH-stretching region. A peak at 3574 cm–1 is identified as that from end-member hydroxylapatite. A second major peak at 3548 cm–1 is only found in mixed chlorapatite-hydroxylapatite solid solutions, as is a third peak at 3592 cm–1. Both represent perturbations of the OH-stretching vibration as compared to hydroxylapatite, to lower and higher frequency, respectively. Both of the new peaks are the result of a Clb-OH sequence, with adjacent anions in crystallographically similar positions, both above or both below adjacent mirror planes. One configuration has the hydrogen atom pointed toward the chlorine atom. The second has the hydrogen of the OH group pointed away from the chlorine atom. Both configurations present novel problems. The shift to lower wavenumber at 3548 cm–1 is characteristic of hydrogen bonding in fluorapatite-hydroxylapatite mixtures, yet the distance between O(H) and Clb is too great to allow it. The shift of OH-stretching vibrations to lower wavenumber is produced through changes in polarization of intervening Cl-Ca2′ (or Ca2) and Ca2(′)-O3 bonds, which are affected by the presence of the large chlorine atom. Lowering the OH-stretching vibration mimics the expected effect of chlorine on a neighboring OH group in the apatite c-axis column, though without hydrogen bonding. The shift to higher wavenumbers, i.e., higher frequency at 3592 cm–1, is the opposite of that expected for hydrogen bonding between column anions in the apatite mineral group. It is ascribed to the interaction between an adjacent Clb and the oxygen end of an adjacent OH dipole. This pairing places an oxygen and a chlorine atom in close proximity. Possible means of accommodation are discussed. A ubiquitous peak at 3498 cm–1 represents hydrogen bonding between an OH and the OHa site, with an interoxygen distance of about 2.9 Å. Published modeling supports the hypothesis that the OHa site is occupied by an O rather than an OH. However, no clear counterpart to this pairing is observed in crystal structure refinements for specimens lacking OHa, although the infrared absorbance is present. The existence of oxyapatite is inferred from studies of plasma-sprayed biomaterials, but the crystal-lographic details of the substitution have remained elusive. A minor shoulder at 3517 cm–1 does not have a clear counterpart in the structural refinements. Sequences of three columnar anions (e.g., OH-Cl-OH or Cl-OH-OH) can be ruled out, but an unequivocal assignment awaits further research.

Enzymatic, structural, and biophysical characterization of a single-domain antibody (VHH) selectively and tightly inhibiting neutrophil elastase and exhibiting favorable developability properties.

Human neutrophil elastase (hNE), a serine protease released by neutrophils during inflammation, plays a major role in the pathophysiology of several conditions especially in inflammatory lung diseases. Its inhibition constitutes, therefore, a promising therapeutic strategy to combat these diseases. In this work, we characterized the in vitro properties of a VHH (i.e., the antigen binding domain of camelid heavy chain-only antibodies), referred to as NbE201. This VHH is able to inhibit tightly, selectively and competitively both human and murine elastases with the inhibition constants (Ki) of 4.1 ± 0.9 nM and 36.8 ± 3.9 nM, respectively. The IC50 for the inhibition of the hydrolysis of elastin is in the same range to that of alpha-1 antitrypsin (i.e., the main endogenous inhibitor of hNE also used in the clinic) and 14 times better than that of Sivelestat (i.e., the 2nd clinically approved hNE inhibitor). The X-ray crystal structure of the NbE201-hNE complex reveals that the Complementarity Determining Regions CDR1 and CDR3 of the VHH bind into the substrate binding pocket of hNE and prevent the access to small or macromolecular substrates. They do not, however, bind deep enough into the pocket to be hydrolyzed. NbE201 is highly stable towards oxidation, deamidation, and chemical or thermal denaturation. NbE201 is therefore likely to tolerate manufacturing processes during drug development. These results highlight the high potential of NbE201 as a (pre)clinical tool to diagnose and treat diseases associated with excessive hNE activity, and for fundamental research to better understand the role of hNE in these conditions.