Search Results (406)

Background: Local anesthesia is essential for most dental procedures, but its parenteral administration is often painful. Topical anesthetics are commonly used to minimize local anesthesia pain; however, commercial formulations fail to fully prevent the discomfort of local anesthetic injection. Methods: We developed and characterized a novel lidocaine and epinephrine co-loaded liquid crystalline precursor system (LCPS) for topical anesthesia. The formulation was structurally characterized using polarized light microscopy (PLM) and small-angle X-ray scattering (SAXS). Rheological behavior was assessed through continuous and oscillatory rheological analyses. Texture profile analysis, in vitro mucoadhesive force evaluation, in vitro drug release and permeation studies, and an in vivo toxicity assay using the chicken chorioallantoic membrane (CAM) model were also conducted. Results: PLM and SAXS confirmed the transition of the LCPS from a microemulsion to a lamellar liquid crystalline structure upon contact with artificial saliva. This transition enhanced formulation consistency by over 100 times and tripled mucoadhesion strength. The LCPS also provided controlled drug release, reducing permeation flow by 93% compared to the commercial formulation. Importantly, the CAM assay indicated that the LCPS exhibited similar toxicity to the commercial product. Conclusions: The developed LCPS demonstrated promising physicochemical and biological properties for topical anesthesia, including enhanced mucoadhesion, controlled drug delivery, and acceptable biocompatibility. These findings support its potential for in vivo application and future clinical use to reduce pain during dental anesthesia procedures. Full article

The recent discovery of Orthonairovirus songlingense (SGLV) and Norwavirus beijiense (BJNV) in China has raised significant concern due to their potential to cause severe human disease. However, little is known about the structural features and function of their nucleoproteins, which play a key role in the viral life cycle. By combining small-angle X-ray scattering (SAXS) data and AlphaFold 3 simulations, we reconstructed the BJNV and SGLV nucleoprotein structures for the first time. The SGLV and BJNV nucleoproteins have structures that are broadly similar to those of Orthonairovirus haemorrhagiae (CCHFV) nucleoproteins despite low sequence similarity. Based on structural analysis, several residues located in the positively charged region of BJNV and SGLV nucleoproteins have been indicated to be important for viral RNA binding. A positively charged RNA-binding crevice runs along the interior of the SGLV and BJNV ribonucleoprotein complex (RNP), shielding the viral RNA. Despite the high structural similarity between SGLV and BJNV nucleoprotein monomers, their RNPs adopt distinct conformations. These findings provide important insights into the molecular mechanisms of viral genome packaging and replication in these emerging pathogens. Also, our work demonstrates that experimental SAXS data can validate and improve predicted AlphaFold 3 structures to reflect their solution structure and also provides the first low-resolution structures of the BJNV and SGLV nucleoproteins for the future development of POC tests, vaccines, and antiviral drugs. Full article

Background/Objectives: Hot-melt extrusion (HME) has become a key technology in pharmaceutical formulation, particularly for enhancing the solubility of poorly soluble Active Pharmaceutical Ingredients (APIs). While horizontal HME is widely adopted, vertical HME remains underexplored despite its potential benefits in footprint reduction, feeding efficiency, temperature control, and integration into continuous manufacturing. This study investigates vertical HME as an innovative approach in order to optimize drug polymer interactions and generate stable amorphous dispersions with controlled release behavior. Methods: Extrusion trials were conducted using a vertical hot-melt extruder developed by Rondol Industrie (Nancy, France). Acetylsalicylic acid (ASA) supplied by Seqens (Écully, France) was used as a model API and processed with Soluplus^® and Kollidon^® 12 PF (BASF, Ludwigshafen, Germany). Various process parameters (temperature, screw speed, screw profile) were explored. The extrudates were characterized by powder X-ray diffraction (PXRD) and small-angle X-ray scattering (SAXS) to evaluate crystallinity and microstructure. In vitro dissolution tests were performed under sink conditions using USP Apparatus II to assess drug release profiles. Results: Vertical HME enabled the formation of homogeneous amorphous solid dispersions. PXRD confirmed the absence of residual crystallinity, and SAXS revealed nanostructural changes in the polymer matrix influenced by drug loading and thermal input. In vitro dissolution demonstrated enhanced drug release rates compared to crystalline ASA, with good reproducibility. Conclusions: Vertical HME provides a compact, cleanable, and modular platform that supports the development of stable amorphous dispersions with controlled release. It represents a robust and versatile solution for pharmaceutical innovation, with strong potential for cost-efficient continuous manufacturing and industrial-scale adoption. Full article

An electrochemical immunosensor for the quantification of prostate-specific antigens (PSAs) using silver nanocrystals (AgNCs) is reported. The silver nanocrystals were synthesized using a conventional citrate reduction protocol. The silver nanocrystals were characterized using scanning electron microscopy (SEM) and field effect scanning electron microscopy (FESEM), X-ray diffraction (XRD), high-resolution transmission electron microscopy (HRTEM), Fourier-transform infrared spectroscopy (FTIR), UV-Vis spectroscopy, and small-angle X-ray scattering (SAXS). The proposed immunosensor was fabricated on a glassy carbon electrode (GCE), sequentially, by drop-coating AgNCs, the electro-deposition of EDC-NHS, the immobilization of anti-PSA antibody (Ab), and dropping of bovine serum albumin (BSA) to prevent non-specific binding sites. Each stage of the fabrication process was characterized by cyclic voltammetry (CV). Using square wave voltammetry (SWV), the proposed immunosensor displayed high sensitivity in detecting PSA over a concentration range of 1 to 10 ng/mL with a detection limit of 1.14 ng/mL and R² of 0.99%. The immunosensor was selective in the presence of interfering substances like glucose, urea, L-cysteine, and alpha-methylacyl-CoA racemase (AMACR) and it showed good stability and repeatability. These results compare favourably with some previously reported results on similar or related technologies for PSA detection. Full article

Ethyl cellulose (EC) and its derivatives are known to exhibit the cholesteric liquid crystal (CLC) phase with visible light reflection in a lyotropic manner after adding appropriate solvents. Generally, the reflection peak of conventional CLCs is easily wavelength shifted by temperature. However, our previous study showed that the reflection wavelength can be maintained even after heating for the lyotropic CLCs of completely pentyl-etherified EC derivatives with methacrylic acid (MAA). However, the emergence of thermally stable reflection colors still remains obscure in the mechanism at the mesoscopic scale. In this study, we evaluated the temperature dependence of the reflection wavelength for the lyotropic CLCs of a series of completely etherified EC derivatives possessing different alkoxy chains by addition of MAA. It was found that butyl- or pentyl-etherified EC derivatives are suitable for preparation of the lyotropic CLCs with visible Bragg reflection, whereas visible light reflection cannot be observed for the other mixtures of propyl- and hexyl-etherified EC derivatives with MAA. Furthermore, it turned out that lyotropic CLCs of pentyl-etherified EC derivatives with MAA show the smallest temperature dependence of their reflection wavelength. Based on the results of ultra-small-angle X-ray scattering (USAXS) and small-angle X-ray scattering (SAXS) measurements of CLC films, we presumed that the emergence of thermally stable reflection colors from the lyotropic CLCs of pentyl-etherified EC derivatives with MAA arises from their phase separation at the mesoscopic scale by changing the temperature. Full article

Main-chain conjugated and non-conjugated polyelectrolytes are an important class of materials that have many technological applications ranging from fire-retardant materials to carbon-nanotube composites, nonlinear optical materials, electrochromic materials for smart windows, and optical sensors for biomolecules. Here, we describe a series of poly(pyridinium salt)s-fluorene containing 9,9-bis(4-aminophenyl)fluorene moieties with various organic counterions that were synthesized using ring-transmutation polymerization and metathesis reactions, which are non-conjugated polyelectrolytes. Their chemical structures were characterized by Fourier transform infrared (FTIR), proton (¹H) and fluorine 19 (¹⁹F) nuclear magnetic resonance (NMR) spectrometers, and elemental analysis. They exhibited polyelectrolytic behavior in dimethyl sulfoxide. Their lyotropic liquid-crystalline phases were examined by polarizing optical microscopy (POM) and small angle X-ray scattering (SAXS) studies. Their emission spectra exhibited a positive solvatochromism on changing the polarity of solvents. They emitted greenish-yellow lights in polar organic solvents. They formed aggregates in polar aprotic and protic solvents with the addition of water (v/v, 0–90%), whose λ_em peaks were blue shifted. Full article

Cyclic Olefin Copolymer (COC) is an amorphous thermoplastic polymer synthesized through the catalytic copolymerization of α-olefin and cyclic olefin. When used in pre-filled syringes and pharmaceutical packaging, COCs require radiation sterilization. The radiation sterilization alters the microstructure of COC, which ultimately affects its performance and biosafety. In this study, to investigate the effects of γ-radiation on COC microstructures, ethylene-norbornene copolymers with various compositions, representative of COC, are studied by nuclear magnetic resonance (NMR) and small angle X-ray scattering (SAXS) techniques. During irradiation, the COC containing 35 mol% norbornene produced free radicals that triggered migration and reaction processes, leading to the formation of entanglements within flexible chain segments. This, in turn, affected nearby ring structures with high steric hindrance, resulting in a 9.2% decrease in internal particle size and an increase in particle spacing. Conversely, when the norbornene content in COC was increased to 57 mol%, the internal particle size increased by 17.9%, while the particle spacing decreased. Full article

Proton exchange membrane (PEM) is a key component of PEM fuel cells, where the membrane plays a decisive role in determining system efficiency and overall performance. The modification of PEMs with hydrophilic dopants represents a promising strategy for extending the operational range of these devices, particularly in low-humidity and high-temperature regimes. In this study, Nafion membranes were modified with silica nanoparticles via the sol–gel method; samples with 1, 3, 5, and 10 wt.% of SiO₂ were obtained. Evaluation of key parameters demonstrated improvement of water uptake and proton conductivity for modified membranes with silica content up to 5 wt.%, while no significant changes in thermal stability (30–700 °C) were observed. The structural changes in the composite membranes were investigated using the small-angle X-ray scattering (SAXS) technique. SAXS data were analyzed using a model-dependent approach: the spherical ionic domain model was modified to account for the scattering contribution from silica nanoparticles. The results obtained demonstrated a reduction in the size of unmodified ionic domains, indicating reorganization of the composite membrane’s microstructure. Full article

Lipid nanoparticles (LNPs) are widely recognized as effective drug delivery systems for RNA therapeutics because their efficacy is critically dependent on structural organization. The mesoscopic architecture of these multicomponent systems, which is governed by interactions among ionizable lipids, structural lipids, nucleic acids, and stabilizers, dictates encapsulation efficiency, biodistribution, and therapeutic performance. Although small-angle X-Ray scattering (SAXS) enables nanostructure characterization, the absence of suitable analytical models has hindered LNP development. Here, we present a core-triple shell SAXS model that resolves LNP hierarchical organization, including the inner lipid layer, intermediate hydrophilic region, and outer PEG corona. For LNPs encapsulating mRNA, a Gaussian distribution model was implemented to characterize the quasi-periodic structure originating from the self-assembly of mRNA-ionizable lipid complexes. Validation studies employing Comirnaty-based LNPs demonstrated that controlled variation of nitrogen-to-phosphorus (N/P) ratios produced distinguishable structural features that establish quantitative correlations between N/P ratios and LNP mesoscopic assembled structure. The modeling framework provides pharmaceutical researchers with robust analytical tools for systematic stability assessment and precision formulation for the optimization of LNPs. These structural insights are expected to advance the development of next-generation RNA therapeutics by potentially enhancing their delivery efficiency and pharmacokinetic properties. Full article

We developed highly stable shellac-based emulsions that incorporated alginate (Al) and κ-carrageenan (Kcar), two anionic polysaccharides capable of undergoing in situ crosslinking for various applications. The stability, droplet size distribution, and microstructure of these emulsions were assessed. Fluorescence microscopy confirmed nanoparticle accumulation at the oil–water interface, which enhanced stability. By leveraging the crosslinking potential of the polysaccharides, we created Pickering emulsion hydrogels (PEH) loaded with curcumin, a model food supplement with poor water solubility, and evaluated their release profiles in an in vitro gastrointestinal model. The results demonstrated two distinct release behaviors: full release in the small intestine and targeted release in the large intestine. Further study revealed fundamental differences in how Al and Kcar influence creaming, which led to a deeper investigation into the mechanisms behind these differences. Rheology measurements showed that a more complex mechanism governs the system’s viscosity. Small angle X-ray scattering (SAXS), Fourier transform infrared spectroscopy (FTIR), and further viscosity measurements revealed that hydrogen bonding in the Kcar emulsions formed unique structures, which provided superior resistance to creaming. This study highlights the potential of tailoring emulsion hydrogels for specific applications in food and drug delivery systems and offers new insights into the structural dynamics of biopolymer-stabilized emulsions. Full article

Biological materials are distinguished by their hierarchical structures in which the organization of the basic building blocks is precisely controlled on many discrete length scales. This biophysical organization, i.e., the structure, along with the biochemical attributes, dictates their properties and function. This article is a review, and also a tutorial, that describes the use of small-angle X-ray scattering (SAXS) for determining the structures at the nanometer and sub-micron length scales in three distinct classes of scattering patterns that arise from fibrous structures, lamellae, and solutions. Fibrous structures are discussed using results from collagen, bone, hair, feathers, and silk. The use of SAXS to study the lamellar structures is illustrated using the results from myelin and membranes. SAXS in solutions is discussed by highlighting the results from multidomain proteins such as monoclonal antibodies and facile structures in intrinsically disordered proteins and protein condensates. The goal is to describe the different methods for analyzing the distinct classes of scattering patterns arising from 1- and 2-D ordered structures and from 3D structures in solutions and to illustrate how the structure imparts unique functions and properties to the biological materials. An understanding of the hierarchical structures in biology is expected to be useful in medical diagnosis and serve as a guide for fabricating functional biomaterials by mimicking these structures. Full article

Poly(A) Binding Protein Nuclear 1 (PABPN1) is a nuclear poly(A)-binding protein that is highly conserved in eukaryotes. It plays multifaceted roles in RNA processing and metabolism, with its dysregulation closely linked to various diseases. PABPN1 contains an alanine-rich N-terminus, a central coiled-coil domain (CC), a conserved RNA recognition motif (RRM) and a C-terminal extension. PABPN1 influences mRNA splicing and stability through its RNA-binding capabilities, thereby modulating gene expression. While PABPN1 is known to interact with RNA, the molecular mechanism underlying this interaction with RNA awaits further investigation. Here, we designed and purified a PABPN1 fragment encompassing the RNA-binding domain (CCRRM fragment, amino acids 114–254). Using a combination of 3D modeling, small-angle X-ray scattering (SAXS) and selective 2′-hydroxyl acylation analyzed by primer extension (SHAPE) assay, our result indicated that CCRRM exhibits a high affinity for poly(A) RNA, a moderate affinity for GU-rich and CU-rich sequences, and negligible binding to AU-rich and CA-rich sequences. RNA binding induces conformation change in the CC. These results suggest that PABPN1 could potentially be involved in cytoplasmic polyadenylation and may influence the regulation of mRNA translation and degradation, although further investigation is required to confirm this role. Full article

Structural analyses of protein filaments formed by self-assembly, such as actin, tubulin, or recombinase filaments, have suffered for decades from technical issues due to difficulties in crystallization, their large size, or the dynamic behavior inherent to their cellular function. The advent of cryo-electron microscopy has finally enabled us to obtain structures at different stages of the existence of these filaments. However, these structures correspond to frozen states, and the possibility of observations in solution is still lacking, especially for filaments characterized by a high plasticity, such as the RecA protein for homologous recombination. Here, we use a combination of SAXS measurements and integrative modeling to generate the solution structure of two known forms of the RecA nucleoprotein filament, previously characterized by electron microscopy and resolved by X-ray crystallography. The two forms differ in the cofactor bound to RecA–RecA interfaces, either ATP or ADP. Cooperative transition from one form to the other has been observed during single-molecule experiments by pulling on the filament but also in solution by modifying solvent conditions. We first compare the SAXS data against known structural information. While the crystal structure of the ATP form matches well with the SAXS data, we deduce from the SAXS profiles of the ADP-form values of the pitch (72.0 Å) and the number of monomers per turn (6.4) that differ with respect to the crystal structure (respectively, 82.7 Å and 6.0). We then monitor the transition between the two states driven by the addition of magnesium, and we show this transition occurs with 0.3 mM Mg ²⁺ ions with a high cooperativity. Full article

Background: Micelles have attracted significant interest in nanomedicine as drug delivery systems. This study investigates the morphology of micelles formed by the D-α-tocopherol polyethylene glycol 1000 succinate (VitE-TPGS) surfactant in the presence and absence of, respectively, a poorly soluble pharmaceutical compound (PSC), i.e., Eltrombopag (0.08 wt%) and CaCl₂ (0.03 wt%). The aim was to assess the micelles’ ability to solubilize the PSC and potentially shield it from Ca²⁺ ions, simulating in vivo conditions. Methods: For this purpose, we have developed a novel theoretical approach for analyzing Pair Distribution Function (PDF) data derived from Small-Angle X-ray Scattering (SAXS) measurements, based on the use of PDF’s moments. Results: Our spheroid-based model was able to characterize successfully the micellar morphology and their interactions with PSC and CaCl₂, providing detailed insights into their size, shape, and electron density contrasts. The presence of PSC significantly affected the shape and integral of the PDF curves, indicating incorporation into the micelles. This also resulted in a decrease in the micelle size, regardless of the presence of CaCl₂. When this salt was added, it reduced the amount of PSC within the micelles. This is likely due to a decrease in the overall PSC availability in solution, induced by Ca²⁺ ions. Conclusions: This advanced yet straightforward analytical model represents a powerful tool for characterizing and optimizing micelle-based drug delivery systems. Full article

Gelatin, a water-soluble protein, shows unique gellification properties, which determine the active commercial availability of gelatin hydrogels in modern alimentary, cosmetic, and pharmaceutical applications. The traditional sources of gelatin for industrial technologies are pork and bovine skin and bones, which sometimes produce religious and some other restrictions. In recent years, there has been a significant increase in the production of gelatin from alternative sources, such as raw fish materials. Unfortunately, fish gelatin is characterized by weak gelling ability and a decrease in gelation and melting temperature, which are a consequence of the amino acid composition and structural features of fish gelatin. One of the ways to strengthen the natural gelling properties of fish gelatin is the structural modification of gelatin hydrogels by the introduction of polysaccharides of various natural origins. We have studied the association of our laboratory-made fish gelatin with three polysaccharides, namely, κ-carrageenan, alginate, and chitosan, which have distinct chemical structures and gelling capabilities. Structural features of the studied systems were analyzed by small-angle X-ray scattering (SAXS), powder X-ray diffraction (PXRD), and scanning electron microscopy (SEM). We applied computer modeling of molecular interactions between fish gelatin and polysaccharides by means of molecular docking and molecular dynamics approaches. The existence of a correlation between the structure of gelatin-polysaccharide systems and their physicochemical properties was demonstrated by wetting angles (flow angles) and dynamic light scattering (DLS) studies of hydrodynamic sizes and surface ζ-potential. Full article