The Role of pH and Ionic Strength in the Attraction-Repulsion Balance of Fibrinogen Interactions

Emulsion-Based Encapsulation of Fibrinogen with Calcium Carbonate for Hemorrhage Control

Hemorrhage, particularly non-compressible torso bleeding, remains the leading cause of preventable death in trauma. Self-propelling hemostats composed of thrombin-calcium carbonate (CaCO3) particles and protonated tranexamic acid (TXA+) have been shown to reduce blood loss and mortality in severe bleeding animal models. To further enhance both hemostatic and self-propelling properties, this study was to investigate fibrinogen-CaCO3 particles prepared via a water-oil-water (W/O/W) emulsion method. The particles were characterized using light and fluorescence microscopy, gel electrophoresis, rotational thromboelastometry (ROTEM), and video motion tracking. The method produced spherical micrometer-sized particles with various yields and fibrinogen content, depending on the preparation conditions. The highest yield was achieved with sodium carbonate (SC), followed by ammonium carbonate (AC) and sodium bicarbonate (SBC). AC and paraffin generated smaller particles compared to SC and heptane, which were used as the carbonate source and oil phase, respectively. Fibrinogen incorporation led to an increase in particle size, indicating a correlation between fibrinogen content and particle size. Fluorescence microscopy confirmed successful fibrinogen encapsulation, with various amounts and hemostatic effects as assessed by gel electrophoresis and ROTEM. Combining fibrinogen-CaCO3 particles with TXA+ and thrombin-CaCO3 particles showed synergistic hemostatic effects. All fibrinogen-encapsulated particles exhibited self-propulsion when mixed with TXA+ and exposed to water, regardless of fibrinogen content. This study advances current hemostatic particle technology by demonstrating enhanced self-propulsion and fibrinogen incorporation via the W/O/W emulsion method. Further optimization of the encapsulation method could enhance the effectiveness of fibrinogen-CaCO3 particles for hemorrhage control.

Impact of pH-dependent dynamics of human serum proteins on dialysis membranes: Cryptographic structure assessment, synchrotron imaging of membrane-protein adsorption, and molecular docking studies

Proteins are fundamental to biochemical processes and critical in hemodialysis. This study investigates the impact of pH on human serum albumin (HSA), fibrinogen (FB), and transferrin (TRF) interactions with polyarylethersulfone (PAES) hemodialysis membranes. A multi-method approach was utilized, including protein crystallography for structural insights, hydration layer analysis to explore solvation and interaction potentials, molecular docking using AutoDock 4.0 for binding affinity simulations, and in-situ X-ray synchrotron SR-μCT imaging to observe protein deposition dynamics. Molecular docking revealed that PAES demonstrated superior binding energies and interaction patterns with FB and TRF compared to cellulose triacetate (CTA), facilitated by specific hydrogen bonding within a water shell. CTA displayed weaker, hydration-sensitive interactions varying with pH. Imaging studies indicated that FB showed higher adsorption at pH 6 than at pH 7.2, predominantly in the middle membrane regions. Similarly, HSA and TRF exhibited increased adsorption at pH 6, suggesting a stronger affinity under acidic conditions. Mixed protein solutions also indicated higher adsorption at pH 6, emphasizing an increased risk of membrane fouling. These findings highlight the crucial role of pH in modulating protein-membrane interactions and enhancing the efficacy of hemodialysis. A deeper understanding of hydration environments and their effects on protein binding affinities provides valuable insights for optimizing membrane design and performance. Clinically, this research suggests that fine-tuning pH during hemodialysis could mitigate protein fouling on membranes, thereby improving procedural efficiency and potentially leading to better patient outcomes through enhanced dialysis effectiveness.

Development of HEMA-Succinic Acid-PEG Bio-Based Monomers for High-Performance Hydrogels in Regenerative Medicine

In recent years, hydrogels have found a special place in regenerative medicine for tissue repair, rehabilitation, and drug delivery. To be used in regenerative medicine, hydrogels must have desirable physical, chemical, and biological properties. In this study, a new biomonomer based on hydroxyethyl methacrylate-succinic acid-polyethylene glycol 200 (HEMA-Suc-PEG) was synthesized and characterized. Then, using the synthesized monomers and different ratios of polyethylene glycol diacrylate (PEGDA) as a crosslinker, biocompatible hydrogels were synthesized through thermal and UV curing methods. The mechanical, physical, chemical, and biological properties of the hydrogels and the behavior of endothelial cells, an essential component of the cardiovascular system, were evaluated. The results showed that the hydrogel synthesized with 0.2 g of PEGDA (UV curing) has desirable mechanical and physical properties. Biological tests showed that these hydrogels are not only nontoxic to cells but also enhance cell adhesion. Therefore, the hydrogel containing the synthesized monomer HEMA-Suc-PEG and 0.2 g of PEGDA has the potential to be used in the cardiovascular system.

Impact of Temperature on the Self-Assembly of Fibrinogen in Thrombin-Free Solutions

Self-assembly of thrombin-free solutions of fibrinogen can be triggered not only by a drop in the ionic strength but also by an appropriate decrease in temperature. Accordingly, an in situ study of self-assembly of fibrinogen in saline buffered solution is carried out by means of time-resolved light scattering providing the molar mass, geometric size, and hydrodynamic radius of the growing intermediates. The resulting data provide access to the morphology of the intermediates and to the mechanism in which these intermediates grow during the early stages of self-assembly. Modeling the results of concentration dependent experiments based on temperature gradients in terms of a chain growth mechanism leads to the corresponding molar standard enthalpy and entropy of aggregation.

Colloid Transport in Bicontinuous Nanoporous Media

Colloid transport and retention in porous media are critical processes influencing various Earth science applications, from groundwater remediation to enhanced oil recovery. These phenomena become particularly complex in the confined spaces of nanoporous media, where strong boundary layer effects and nanoconfinement significantly alter colloid behavior. In this work, we use particle dynamics models to simulate colloid transport and retention processes in bicontinuous nanoporous (BNP) media under pressure gradients. By utilizing particle-based models, we track the movement of each colloid and elucidate the underlying colloid retention mechanisms. Under unfavorable attachment conditions, the results reveal two colloid retention mechanisms: physical straining and trapping in low-flow zone. Furthermore, we investigate the effects of critical factors including colloid volume fraction, d, pressure difference, ΔP, interaction between colloids and BNP media, Ec-p, and among colloids, Ec-c, on colloid transport. Analysis of breakthrough curves and colloid displacements demonstrates that higher values of d, lower values of ΔP, and strong Ec-p attractions significantly increase colloid retention, which further lead to colloid clogging and jamming. In contrast, Ec-c has minimal impact on colloid transport due to the limited colloid-colloid interaction in nanoporous channels. This work provides critical insights into the fundamental factors governing colloid transport and retention within stochastic nanoporous materials.

Gadd45β is critical for regulation of type I interferon signaling by facilitating G3BP-mediated stress granule formation

Stress granules (SGs) constitute a signaling hub that plays a critical role in type I interferon responses. Here, we report that growth arrest and DNA damage-inducible beta (Gadd45β) act as a positive regulator of SG-mediated interferon signaling by targeting G3BP upon RNA virus infection. Gadd45β deficiency markedly impairs SG formation and SG-mediated activation of interferon signaling in vitro. Gadd45β knockout mice are highly susceptible to RNA virus infection, and their ability to produce interferon and cytokines is severely impaired. Specifically, Gadd45β interacts with the RNA-binding domain of G3BP, leading to conformational expansion of G3BP1 via dissolution of its autoinhibitory electrostatic intramolecular interaction. The acidic loop 1- and RNA-binding properties of Gadd45β markedly increase the conformational expansion and RNA-binding affinity of the G3BP1-Gadd45β complex, thereby promoting assembly of SGs. These findings suggest a role for Gadd45β as a component and critical regulator of G3BP1-mediated SG formation, which facilitates RLR-mediated interferon signaling.

Protein translational diffusion as a way to detect intermolecular interactions

In this work, we analyze the information on the protein intermolecular interactions obtained from macromolecular diffusion. We have shown that the most hopeful results are given by our approach based on analysis of protein translational self-diffusion and collective diffusion obtained by dynamic light scattering and pulsed-field gradient NMR (PFG NMR) spectroscopy with the help of Vink's approach to analyze diffusion motion of particles by frictional formalism of non-equilibrium thermodynamics and the usage of the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory of colloid particles interactions in electrolyte solutions. Early we have shown that integration of Vink's theory with DLVO provides a reliable basis for uniform interpreting of PFG NMR and DLS experiments on concentration dependence of diffusion coefficients. Basic details of theoretical and mathematical procedures and a broad analysis of experimental attestation of proposed conception on proteins of various structural form, size, and shape are presented. In the present review, the main capabilities of our approach obtain the details of intermolecular interactions of proteins with different shapes, internal structures, and mass. The universality of Vink's approach is experimentally shown, which gives the appropriate description of experimental results for proteins of complicated structure and shape.

Extent of N-Terminus Folding of Semenogelin 1 Cleavage Product Determines Tendency to Amyloid Formation

It is known that four peptide fragments of predominant protein in human semen Semenogelin 1 (SEM1) (SEM1(86-107), SEM1(68-107), SEM1(49-107) and SEM1(45-107)) are involved in fertilization and amyloid formation processes. In this work, the structure and dynamic behavior of SEM1(45-107) and SEM1(49-107) peptides and their N-domains were described. According to ThT fluorescence spectroscopy data, it was shown that the amyloid formation of SEM1(45-107) starts immediately after purification, which is not observed for SEM1(49-107). Seeing that the peptide amino acid sequence of SEM1(45-107) differs from SEM1(49-107) only by the presence of four additional amino acid residues in the N domain, these domains of both peptides were obtained via solid-phase synthesis and the difference in their dynamics and structure was investigated. SEM1(45-67) and SEM1(49-67) showed no principal difference in dynamic behavior in water solution. Furthermore, we obtained mostly disordered structures of SEM1(45-67) and SEM1(49-67). However, SEM1(45-67) contains a helix (E58-K60) and helix-like (S49-Q51) fragments. These helical fragments may rearrange into β-strands during amyloid formation process. Thus, the difference in full-length peptides' (SEM1(45-107) and SEM1(49-107)) amyloid-forming behavior may be explained by the presence of a structured helix at the SEM1(45-107) N-terminus, which contributes to an increased rate of amyloid formation.

Effect of Protein–Protein Interactions on Translational Diffusion of Spheroidal Proteins

One of the commonly accepted approaches to estimate protein–protein interactions (PPI) in aqueous solutions is the analysis of their translational diffusion. The present review article observes a phenomenological approach to analyze PPI effects via concentration dependencies of self- and collective translational diffusion coefficient for several spheroidal proteins derived from the pulsed field gradient NMR (PFG NMR) and dynamic light scattering (DLS), respectively. These proteins are rigid globular α-chymotrypsin (ChTr) and human serum albumin (HSA), and partly disordered α-casein (α-CN) and β-lactoglobulin (β-Lg). The PPI analysis enabled us to reveal the dominance of intermolecular repulsion at low ionic strength of solution (0.003–0.01 M) for all studied proteins. The increase in the ionic strength to 0.1–1.0 M leads to the screening of protein charges, resulting in the decrease of the protein electrostatic potential. The increase of the van der Waals potential for ChTr and α-CN characterizes their propensity towards unstable weak attractive interactions. The decrease of van der Waals interactions for β-Lg is probably associated with the formation of stable oligomers by this protein. The PPI, estimated with the help of interaction potential and idealized spherical molecular geometry, are in good agreement with experimental data.