Impact of thermal treatment on halloysite nanotubes: A combined experimental-computational approach.

Halloysite nanotubes (HNTs) are naturally occurring aluminosilicate minerals, known for their unique tubular structure, which have garnered significant interest for a wide range of applications. This study explores the morphological changes of HNTs when subjected to thermal treatment ranging from 25 °C to 1100 °C using a combination of experimental characterization techniques and molecular dynamics simulations. Techniques such as solid-state NMR (SSNMR), X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller (BET) surface area measurements, and Fourier Transform Infrared Spectroscopy (FT-IR) were employed to analyse the structural evolution.

Assessing the effect of acid and alkali treatment on a halloysite-based catalyst for dry reforming of methane.

Dry reforming of methane (DRM) has recently received wide attention owing to its outstanding performance in the reduction and conversion of CH and CO to syngas (H and CO). From an industrial perspective, nickel (Ni)-supported catalysts have been deemed among the most suitable catalysts for DRM owing to their low cost and high activity compared to noble metals. However, a downside of nickel catalysts is their high susceptibility to deactivation due to coke formation and sintering at high temperatures.

Investigation of the Effect of PD-L1 Blockade on Triple Negative Breast Cancer Cells Using Fourier Transform Infrared Spectroscopy.

Interactions between programmed death-1 (PD-1) with its ligand PD-L1 on tumor cells can antagonize T cell responses. Inhibiting these interactions using immune checkpoint inhibitors has shown promise in cancer immunotherapy. MDA-MB-231 is a triple negative breast cancer cell line that expresses PD-L1.

Role of non-electrostatic forces in antimicrobial potency of a dengue-virus derived fusion peptide VG16KRKP: Mechanistic insight into the interfacial peptide-lipid interactions.

Cationic antimicrobial peptides (AMPs) are emerging as effective alternatives to conventional therapeutics that are used against the ever-rising number of multidrug-resistant microbial strains. Most studies established the peptide's amphipathicity and electrostatic interaction with the membrane as the basis for their antimicrobial effect. However, the interplay between the stoichiometric ratio of lipids, local geometry, diverse physicochemical properties of the host membranes and antimicrobial peptide efficacy is still poorly understood.

Application of tungsten disulfide quantum dot-conjugated antimicrobial peptides in bio-imaging and antimicrobial therapy.

Two-dimensional (2D) tungsten disulfide (WS) quantum dots offer numerous promising applications in materials and optoelectronic sciences. Additionally, the catalytic and photoluminescence properties of ultra-small WS nanoparticles are of potential interest in biomedical sciences. Addressing the use of WS in the context of infection, the present study describes the conjugation of two potent antimicrobial peptides with WS quantum dots, as well as the application of the resulting conjugates in antimicrobial therapy and bioimaging.

Electrostatic Constraints Assessed by H MAS NMR Illuminate Differences in Crystalline Polymorphs.

Atomically resolved crystal structures not only suffer from the inherent uncertainty in accurately locating H atoms but also are incapable of fully revealing the underlying forces enabling the formation of final structures. Therefore, the development and application of novel techniques to illuminate intermolecular forces in crystalline solids are highly relevant to understand the role of hydrogen atoms in structure adoption. Novel developments in H NMR MAS methodology can now achieve robust measurements of H chemical shift anisotropy (CSA) tensors which are highly sensitive to electrostatics.

Accelerated molecular dynamics simulation analysis of MSI-594 in a lipid bilayer.

Multidrug resistance against the existing antibiotics is one of the most challenging threats across the globe. Antimicrobial peptides (AMPs), in this regard, are considered to be one of the effective alternatives that can overcome bacterial resistance. MSI-594, a 24-residue linear alpha-helical cationic AMP, has been shown to function via the carpet mechanism to disrupt bacterial membrane systems.

Proton-Based Ultrafast Magic Angle Spinning Solid-State NMR Spectroscopy.

Protons are vastly abundant in a wide range of exciting macromolecules and thus can be a powerful probe to investigate the structure and dynamics at atomic resolution using solid-state NMR (ssNMR) spectroscopy. Unfortunately, the high signal sensitivity, afforded by the high natural-abundance and high gyromagnetic ratio of protons, is greatly compromised by severe line broadening due to the very strong H-H dipolar couplings. As a result, protons are rarely used, in spite of the desperate need for enhancing the sensitivity of ssNMR to study a variety of systems that are not amenable for high resolution investigation using other techniques including X-ray crystallography, cryo-electron microscopy, and solution NMR spectroscopy.

Selective detection and complete identification of triglycerides in cortical bone by high-resolution (1)H MAS NMR spectroscopy.

Using (1)H-based magic angle spinning solid-state NMR spectroscopy, we report an atomistic-level characterization of triglycerides in compact cortical bone. By suppressing contributions from immobile molecules present in bone, we show that a (1)H-based constant-time uniform-sign cross-peak (CTUC) two-dimensional COSY-type experiment that correlates the chemical shifts of protons can selectively detect a mobile triglyceride layer as the main component of small lipid droplets embedded on the surface of collagen fibrils. High sensitivity and resolution afforded by this NMR approach could be potentially utilized to investigate the origin of triglycerides and their pathological roles associated with bone fractures, diseases, and aging.

Evidence for Inhibition of Lysozyme Amyloid Fibrillization by Peptide Fragments from Human Lysozyme: A Combined Spectroscopy, Microscopy, and Docking Study.

Degenerative diseases, such as Alzheimer's and prion diseases, as well as type II diabetes, have a pathogenesis associated with protein misfolding, which routes with amyloid formation. Recent strategies for designing small-molecule and polypeptide antiamyloid inhibitors are mainly based on mature fibril structures containing cross β-sheet structures. In the present study, we have tackled the hypothesis that the rational design of antiamyloid agents that can target native proteins might offer advantageous prospect to design effective therapeutics.

Hybridizing cross-polarization with NOE or refocused-INEPT enhances the sensitivity of MAS NMR spectroscopy.

Heteronuclear cross polarization (CP) has been commonly used to enhance the sensitivity of dilute low-γ nuclei in almost all solid-state NMR experiments. However, CP relies on heteronuclear dipolar couplings, and therefore the magnetization transfer efficiency becomes inefficient when the dipolar couplings are weak, as is often the case for mobile components in solids. Here, we demonstrate methods that combine CP with heteronuclear Overhauser effect (referred to as CP-NOE) or with refocused-INEPT (referred to as CP-RINEPT) to overcome the efficiency limitation of CP and enhance the signal-to-noise ratio (S/N) for mobile components.

Structure and Dynamics of Antifreeze Protein--Model Membrane Interactions: A Combined Spectroscopic and Molecular Dynamics Study.

Antifreeze proteins (AFPs) are the key biomolecules that enable species to survive under subzero temperature conditions. The physiologically relevant activities of AFPs are based on the adsorption to ice crystals, followed by the inhibition of subsequent crystal layer growth of ice, routed with depression in freezing point in a noncolligative manner. The functional attributes governing the mechanism by which AFPs inhibit freezing of body fluids in bacteria, fungi, plants, and fishes are mainly attributed to their adsorption onto the surface of ice within the physiological system.

Proton chemical shift tensors determined by 3D ultrafast MAS double-quantum NMR spectroscopy.

Proton NMR spectroscopy in the solid state has recently attracted much attention owing to the significant enhancement in spectral resolution afforded by the remarkable advances in ultrafast magic angle spinning (MAS) capabilities. In particular, proton chemical shift anisotropy (CSA) has become an important tool for obtaining specific insights into inter/intra-molecular hydrogen bonding. However, even at the highest currently feasible spinning frequencies (110-120 kHz), (1)H MAS NMR spectra of rigid solids still suffer from poor resolution and severe peak overlap caused by the strong (1)H-(1)H homonuclear dipolar couplings and narrow (1)H chemical shift (CS) ranges, which render it difficult to determine the CSA of specific proton sites in the standard CSA/single-quantum (SQ) chemical shift correlation experiment.

Biophysical Characterization of Essential Phosphorylation at the Flexible C-Terminal Region of C-Raf with 14-3-3ζ Protein.

Phosphorylation at the C-terminal flexible region of the C-Raf protein plays an important role in regulating its biological activity. Auto-phosphorylation at serine 621 (S621) in this region maintains C-Raf stability and activity. This phosphorylation mediates the interaction between C-Raf and scaffold protein 14-3-3ζ to activate the downstream MEK kinase pathway.

Proton-Detected Solid-State NMR Spectroscopy of Bone with Ultrafast Magic Angle Spinning.

While obtaining high-resolution structural details from bone is highly important to better understand its mechanical strength and the effects of aging and disease on bone ultrastructure, it has been a major challenge to do so with existing biophysical techniques. Though solid-state NMR spectroscopy has the potential to reveal the structural details of bone, it suffers from poor spectral resolution and sensitivity. Nonetheless, recent developments in magic angle spinning (MAS) NMR technology have made it possible to spin solid samples up to 110 kHz frequency.

Antimicrobial Peptides: Insights into Membrane Permeabilization, Lipopolysaccharide Fragmentation and Application in Plant Disease Control.

The recent increase in multidrug resistance against bacterial infections has become a major concern to human health and global food security. Synthetic antimicrobial peptides (AMPs) have recently received substantial attention as potential alternatives to conventional antibiotics because of their potent broad-spectrum antimicrobial activity. These peptides have also been implicated in plant disease control for replacing conventional treatment methods that are polluting and hazardous to the environment and to human health.

Investigating albendazole desmotropes by solid-state NMR spectroscopy.

Characterization of the molecular structure and physicochemical solid-state properties of the solid forms of pharmaceutical compounds is a key requirement for successful commercialization as potential active ingredients in drug products. These properties can ultimately have a critical effect on the solubility and bioavailability of the final drug product. Here, the desmotropy of Albendazole forms I and II was investigated at the atomic level.

Acceleration of natural-abundance solid-state MAS NMR measurements on bone by paramagnetic relaxation from gadolinium-DTPA.

Reducing the data collection time without affecting the signal intensity and spectral resolution is one of the major challenges for the widespread application of multidimensional nuclear magnetic resonance (NMR) spectroscopy, especially in experiments conducted on complex heterogeneous biological systems such as bone. In most of these experiments, the NMR data collection time is ultimately governed by the proton spin-lattice relaxation times (T1). For over two decades, gadolinium(III)-DTPA (Gd-DTPA, DTPA=Diethylene triamine pentaacetic acid) has been one of the most widely used contrast-enhancement agents in magnetic resonance imaging (MRI).

Insights into atomic-level interaction between mefenamic acid and eudragit EPO in a supersaturated solution by high-resolution magic-angle spinning NMR spectroscopy.

The intermolecular interaction between mefenamic acid (MFA), a poorly water-soluble nonsteroidal anti-inflammatory drug, and Eudragit EPO (EPO), a water-soluble polymer, is investigated in their supersaturated solution using high-resolution magic-angle spinning (HRMAS) nuclear magnetic resonance (NMR) spectroscopy. The stable supersaturated solution with a high MFA concentration of 3.0 mg/mL is prepared by dispersing the amorphous solid dispersion into a d-acetate buffer at pH 5.

Crystallinity and compositional changes in carbonated apatites: Evidence from P solid-state NMR, Raman, and AFM analysis.

Solid-state (magic-angle spinning) NMR spectroscopy is a useful tool for obtaining structural information on bone organic and mineral components and synthetic model minerals at the atomic-level. Raman and P NMR spectral parameters were investigated in a series of synthetic B-type carbonated apatites (CAps). Inverse P NMR linewidth and inverse Raman PO ν bandwidth were both correlated with powder XRD crystallinity over the 0.

insights into novel supramolecular complexes of two solid forms of norfloxacin and β-cyclodextrin.

The solid-state properties of novel complexes of β-cyclodextrin and two different solid forms of norfloxacin were investigated at the molecular level, in an attempt to obtain promising candidates for the preparation of alternative matrices used in pharmaceutical oral formulations. In order to evaluate the physical properties inherited from the different polymorphs, these supramolecular systems were characterized using a variety of spectroscopic techniques including natural-abundance (13) C cross-polarization magic-angle-spinning (CP-MAS) nuclear magnetic resonance (NMR), powder X-ray diffraction, and Fourier transform infrared spectroscopy. The intrinsic proton spin-lattice relaxation times detected in (13) C CP-MAS NMR spectra are used to confirm and distinguish the complex formation, as well as to provide better insights into the molecular fragments that are involved in the interaction with β-cyclodextrin.

High-resolution structural insights into bone: a solid-state NMR relaxation study utilizing paramagnetic doping.

The hierarchical heterogeneous architecture of bone imposes significant challenges to structural and dynamic studies conducted by traditional biophysical techniques. High-resolution solid-state nuclear magnetic resonance (SSNMR) spectroscopy is capable of providing detailed atomic-level structural insights into such traditionally challenging materials. However, the relatively long data-collection time necessary to achieve a reliable signal-to-noise ratio (S/N) remains a major limitation for the widespread application of SSNMR on bone and related biomaterials.

High-field solid-state (67)Zn NMR spectroscopy of several zinc-amino acid complexes.

We report the results of our solid-state (67)Zn NMR study of the various zinc sites in four zinc-amino acid coordination complexes: bis(glycinato)zinc(II) monohydrate; bis(l-alaninato)zinc(II); bis(l-histidinato)zinc(II) dihydrate; and sodium bis(l-cysteinato)zincate(II) hexahydrate; as well as a related complex, bis(imidazole)zinc(II) chloride. We demonstrate the advantages of using high (21.1 T) applied magnetic fields for detecting (67)Zn directly at ambient temperatures using the quadrupolar Carr-Purcell Meiboom-Gill (QCPMG) pulse sequence.