Search Results (74)

The ability to assess molecular binding kinetics in real time is critical for advancing our understanding of molecular interactions in biochemical and biotechnological systems. This work presents a novel optical tweezer (OT)-based method to monitor molecular affinity in real time, focusing on the high-affinity streptavidin–biotin system as a model. Transparent poly(methyl methacrylate) (PMMA) microparticles functionalized with streptavidin were trapped before, during, and after binding with biotinylated bovine serum albumin (biotin–BSA), enabling the analysis of forward-scattered signals to detect nanoscale changes in particle size. By applying the Power Spectral Density method, the friction coefficient of individual particles was calculated, allowing for real-time tracking of binding dynamics and the estimation of the association rate constant ($k_{\mathrm{on}}\approx {10}^6{\mathrm{M}}^{-1}{\mathrm{s}}^{-1}$). These results are consistent with literature values and demonstrate the potential of this OT-based approach for non-invasive, label-free detection of molecular interactions. Compared to existing techniques, such as atomic force microscopy and cantilever-based sensors, this method offers significant advantages, including real-time monitoring, adaptability to different bioaffinity systems, and compatibility with miniaturized setups. This work establishes a foundation for using OT-based tools to monitor high-affinity molecular interactions in real time. While demonstrated here using biotinylated BSA as a model ligand, future studies will explore the method’s applicability to smaller ligands and more subtle surface modifications. Full article

This study investigates the protective performance of a triazole-based Mannich base corrosion inhibitor, 4-((1,2,4-triazolyl)methyl) dibutylamine (TZMBA), on P110 carbon steel in dissolved oxygen environments. TZMBA was synthesized via a Mannich reaction, and its molecular structure was confirmed by Fourier transform infrared spectroscopy (FT-IR). The corrosion inhibition behavior and underlying mechanisms were systematically explored through weight loss measurements, surface characterization, and multiscale molecular simulations. Weight loss results indicated that TZMBA significantly mitigates the corrosion of P110 steel, with inhibition efficiency reaching 81.5% at 1.67 mmol/L and 82.0% at 2.14 mmol/L. Adsorption thermodynamic analysis revealed that the process follows the Langmuir isotherm model. The calculated standard Gibbs free energy ${∆G}_{ads}^0$ of −38.69 kJ/mol suggests a spontaneous, mixed-type adsorption mechanism involving both physisorption and chemisorption. Scanning electron microscopy (SEM) observations confirmed a marked reduction in surface degradation, characterized by suppressed corrosion products and minimized localized attack. X-ray photoelectron spectroscopy (XPS) further verified that TZMBA anchors to the metal surface through chemical coordination, forming a robust organic-inorganic composite film. From a theoretical perspective, frontier molecular orbital (FMO) analysis showed that TZMBA’s high E_HOMO and narrow energy gap facilitate efficient electron transfer. Combined Fukui function and molecular electrostatic potential (MEP) maps identified the nitrogen atoms in the triazole ring and amine group as the primary active sites. Furthermore, molecular dynamics (MD) simulations demonstrated that TZMBA molecules adopt a nearly parallel configuration on the Fe surface. The high negative interaction energy obtained from MD simulations confirms a strong binding affinity and a potent inherent driving force for the formation of a stable protective layer. Overall, the integration of experimental data and theoretical calculations establishes TZMBA as an effective inhibitor that provides superior protection by forming a stable, compact adsorption film on P110 carbon steel. Full article

Extracellular vesicles (EVs) are membrane-bound particles secreted by most cell types that play a pivotal role in intercellular communication via transporting protein, nucleic acid, lipid, and metabolite cargos. Among EVs, exosomes are a well-characterized subtype, typically ranging from 10–150 nm in diameter and originating from the endosomal pathway via the formation of multivesicular bodies that fuse with the plasma membrane. EVs/exosomes can be isolated from various biological fluids and cultured cells, with production and yield influenced by the cell type and culture conditions. Isolation methods, including ultracentrifugation or density-based ultracentrifugation, tangential flow filtration, size-exclusion chromatography, immunoaffinity and membrane-affinity capture, and recently developed commercial equipment, offer distinct advantages and limitations in terms of purity, scalability, and exosome integrity. Characterization techniques, such as nanoparticle tracking analysis (NTA), transmission electron microscopy (TEM), cryogenic electron microscopy (cryo-EM), atomic force microscopy (AFM), Western blotting, flow cytometry, and dynamic light scattering (DLS), assess exosome size, morphology, and biomarker expression. Given their biocompatibility and inherent targeting capabilities across a diverse range of diseases, EVs/exosomes hold clinical promise as diagnostic biomarkers, cell-free therapeutics, drug delivery vehicles, immune modulators, and in regenerative medicine. However, these emerging fields in exosome medicine continue to face challenges in standardizing EV sourcing, production, purification, yield, bio-targeting, drug loading, and drug delivery. While EVs/exosomes represent a rapidly advancing frontier in biomedical science, robust protocols for standardization and scalable production will be essential for their successful translation into clinical applications. This article provides a comprehensive overview of EV/exosome origins, their biological functions, the approaches for their isolation and characterization, and their therapeutic potential. Full article

We report the first examples of bent-shaped LC dimers based on a seven-membered bridged stilbene. We synthesized nonylene- and ether-linked cyano-terminated dimers (sC9-tCN and sOC7O-tCN, respectively) and a homologous series of nonylene-linked alkyl-terminated dimers (sC9-tCn) with alkyl carbon atoms n = 1–6. Polarizing optical microscopy, differential scanning calorimetry, and X-ray diffraction measurement were employed to investigate the phase-transition behavior and LC phase structures. sC9-tCN and sOC7O-tCN only exhibited a nematic (N) phase, whereas sC9-tCn (n = 1–5) formed both the N_TB and N phases. sC9-tC5 additionally formed an unidentified X phase from the N_TB phase and sC9-tC6 exhibited a smectic A phase from the N phase. The weak dispersion force and intermolecular affinity provided by the terminal alkyl chains are likely to be preferable to the large dipole–dipole interactions by the cyano termini for the N_TB phase formation of the present dimers. The isotropic points of sC9-tCn showed an odd–even oscillation with n, whereas the N–N_TB phase transition temperatures were comparable. Remarkably, the N_TB stripe textures of sC9-tCn appeared perpendicular to the rubbing direction, and the N–N_TB phase transitions exhibited their second-order nature. This study revealed the unique N_TB phase properties of the 7-membered bridged stilbene-based LC dimers. Full article

Silica spicules provide a natural transdermal conduit but require a linker that binds strongly under physiological conditions and releases payloads selectively in response to biological cues. Existing silane chemistries or polydopamine coatings lack enzyme responsiveness and show limited control over release. We created a 180-member peptide library with the motif L–X1–X2–[Y–F–Y]–A–L–G–P–H–C and screened for silica binding. Biophysical assays (circular dichroism, ζ-potential, quartz crystal microbalance, atomic force microscopy) and molecular dynamics identified high-affinity binders. The lead, P176, was tested for matrix metalloprotease (MMP)-responsive cleavage. Conjugation and release of Vitamin C and Stigmasterol were analyzed by HPLC and Franz diffusion cells. P176 showed high silica affinity (~55 µg mg⁻¹), robust biophysical signals (Δf −35 to −38 Hz; rupture force ~154 pN; ζ shift −22 to−11.5 mV), and favorable adsorption energy (−48.5 kcal mol⁻¹, contact 4.5 nm², 8.5 H-bonds). The MMP gate displayed efficient kinetics (Vmax 117.9 RFU·min⁻¹, Km 5.0 µM) with >90% cleavage at 60 min, reduced to 26% by inhibitor. Conjugation yields reached 87% (Vitamin C) and 77% (Stigmasterol). Franz diffusion showed MMP-dependent release (24 h: Vitamin C 90–96%, Stigmasterol 80–85%) with minimal basal leakage. Released Vitamin C enhanced collagen I to ~250% in fibroblasts, while Stigmasterol attenuated LPS-induced macrophage morphology; keratinocytes retained normal marker expression. This study demonstrates that a single amphipathic, sequence-programmed peptide can couple strong silica anchoring with protease-responsive release and broad payload compatibility, establishing a versatile platform for spicule-based transdermal and regenerative delivery. Full article

We demonstrate that gold nanoparticles (AuNPs) are capable of unwinding double-stranded (ds) DNA. Upon unwinding, the exposed nucleobases of the separated strands adsorb onto the nanoparticle surface, resulting in the coating of the particles. The unwinding process was characterized by Atomic Force Microscopy (AFM) and absorption spectroscopy. Our results show that AuNPs initially bind to single-stranded overhangs at the duplex termini, forming dsDNA–nanoparticle dumbbells. This binding event subsequently initiates the separation of the DNA strands. As the unwinding proceeds, the nanoparticles become progressively wrapped by the unwound DNA strands, which leads to a gradual reduction in the interparticle distance within the dumbbells. This process is driven by the strong affinity of nucleobases for the gold surface. The efficiency of DNA unwinding was found to depend strongly on both nanoparticle size and temperature. These findings provide new insights into DNA-nanoparticle interactions and may facilitate the rational design of DNA–AuNP hybrid nanostructures such as dumbbell-shaped conjugates for applications in DNA-based nanoelectronics, biosensing, and self-assembled nanomaterials. Full article

This work introduces 2-(azulen-1-yldiazenyl)-5-(thiophen-2-yl)-1,3,4-thiadiazole (L) as a functional monomer capable of forming stable, redox-active films with high affinity for lead in aqueous solutions. L was synthesized and characterized using physical chemical methods and electrochemistry. Polymer films of L were prepared through oxidative electro polymerization on glassy carbon electrodes in L solutions in 0.1 M TBAP in acetonitrile. They were characterized through electrochemistry. The surface of chemically modified electrodes (CMEs) prepared through controlled potential electrolysis (CPE) at variable concentrations, potentials, and electric charges was characterized through scanning electron spectroscopy, atomic force microscopy, and Raman spectroscopy, which confirmed the films’ formation. Electrochemical sensing of the films deposited on these CMEs was tested with respect to heavy metal (HM) ion analysis in aqueous solutions to obtain sensors for HMs. The obtained CMEs presented the best characteristics for the recognition of Pb among the investigated HMs (Cd, Pb, Cu, and Hg). Calibration curves were obtained for the analysis of Pb(II) in aqueous solutions, which allowed for the estimation of a good detection limit of this cation (<10⁻⁸ M) for non-optimized CMEs. The resulting CMEs show promise for deployment in portable environmental monitoring systems, with implications for public health protection and environmental safety. Full article

Background: Huang Qin Decoction (HQD) is a well-established Traditional Chinese Medicine (TCM) formulation recognized for its application in the treatment of colorectal cancer (CRC). However, the precise therapeutic mechanisms remain inadequately defined. Methods: This study integrates metabolomics from a mouse model and network pharmacology to screen potential targets and bio-active ingredients of HQD. The pharmacological activity of HQD for CRC was evidenced via single-cell RNA sequencing (scRNA-seq), molecular docking, and molecular dynamics simulations. Atomic force microscopy (AFM) assays and cellular experimental validation were used to confirm the relative mechanisms. Results: The metabolite profile undergoes significant alterations, with metabolic reprogramming evident during the malignant progression of CRC liver metastasis. Network pharmacology analysis identified that HQD regulates several metabolic pathways, including arginine biosynthesis, alanine, aspartate, and glutamate metabolism, nitrogen metabolism, phenylalanine metabolism, and linoleic acid metabolism, by targeting key proteins such as aspartate aminotransferase (GOT1), cytochrome P450 1A2 (CYP1A2), and carbonic anhydrase 2 (CA2). ScRNA-seq analysis indicated that HQD may enhance the functionality of cytotoxic T cells, thereby reversing the immunosuppressive microenvironment. Virtual verification revealed a strong binding affinity between the identified hub targets and active constituents of HQD, a finding subsequently corroborated by AFM assays. Cellular experiments confirmed that naringenin treatment inhibits the proliferation, migration, and invasion of CRC cells by downregulating GOT1 expression and disrupting glutamine metabolism. Conclusions: Computational prediction and in vitro validation reveal the active ingredients, potential targets, and molecular mechanisms of HQD against CRC liver metastasis, thereby providing a scientific foundation for the application of TCM in CRC treatment. Full article

Polyphenylene sulfide (PPS) is becoming increasingly valuable in the electrical, electronic, and automotive industries. In particular, PPS composites reinforced with glass fiber (GF) have better dimensional stability and mechanical properties than conventional PPS materials and can be used in applications like electric vehicle capacitor housing. In the electric vehicle industry, the epoxy-molding process is essential for manufacturing capacitor housings, where the bonding strength between the PPS/GF composites and epoxy significantly affects the durability of the product. However, the inert surface characteristics of polymers like PPS limit their interaction with epoxy, decreasing the bonding strength. This study was aimed at enhancing the bonding strength between PPS/GF composites and epoxy by modifying the PPS surface using atmospheric-pressure plasma treatment. The surface modification resulted in increased surface roughness and the introduction of polar functional groups, which improved both mechanical interlocking and chemical affinity to the epoxy. Surface changes were analyzed using atomic force microscopy and scanning electron microscopy, and chemical characterization was conducted using X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy. Surface energy was determined via contact angle measurements, and bonding strength was evaluated through single-lap shear tests. The results showed a 55% increase in surface energy and a 24.8% improvement in bonding strength due to the surface modification. Full article

Multifunctional self-healing supramolecular structural toughened resins, formulated to counteract the insulating properties of epoxy polymers and integrating auto-repair mechanisms, are morphologically and spectroscopically characterized using Tunneling Atomic Force Microscopy (TUNA) and Fourier transform infrared spectroscopy (FT-IR), respectively. Specifically, the multifunctional resin comprises self-healing molecular fillers and electrically conductive carbon nanotubes (CNTs) embedded in the matrix. The selected self-healing molecules can form non-covalent bonds with the hydroxyl (OH) and carbonyl (C=O) groups of the toughened epoxy matrix through their H-bonding donor and acceptor sites. An FT-IR analysis has been conducted to evaluate the interactions that the barbiturate acid derivatives, serving as self-healing fillers, can form with the constituent parts of the toughened epoxy blend. Tunneling Atomic Force Microscopy (TUNA) highlights the morphological characteristics of CNTs, their dispersion within the polymeric matrix, and their affinity for the globular rubber domains. The TUNA technique maps the samples’ electrical conductivity at micro- and nanoscale spatial domains. Detecting electrical currents reveals supramolecular networks, determined by hydrogen bonds, within the samples, showcasing the morphological features of the sample containing an embedded conductive nanofiller in the hosting matrix. Full article

The perivitellin-2 (PV2) from snails is an unusual neuro and enterotoxin comprising a pore-forming domain of the Membrane Attack Complex and Perforin Family (MACPF) linked to a lectin. While both domains have membrane binding capabilities, PV2’s mechanism of action remains unclear. We studied the apple snail Pomacea maculata PV2’s (PmPV2’s) interaction with lipid membranes using various biophysical and cell biology approaches. In vitro studies showed that PmPV2 toxicity decreased when cholesterol (Chol) was diminished from enterocyte cell membranes. Chol enhanced PmPV2 association with phosphatidylcholine membranes but did not induce pore formation. In contrast, using rat brain lipid models, rich in glycolipids, PmPV2 exhibited high affinity and induced vesicle permeabilization. Negative stain electron microscopy and atomic force microscopy confirmed the formation of pore-like structures in brain lipid vesicles. Our findings suggest that Chol is a necessary lipid component and point to PmPV2–glycolipid interactions as potential activators critical to triggering PmPV2’s pore-forming activity, providing insights into this novel toxin’s mechanism. Full article

This article compares two new textile materials used to clean up spills of oil or two oil products (crude oil, diesel fuel, and base oil SN 150). The plain-woven cotton fabric is hydrophilic, with a typical porous structure. After coating with a layer of chitosan modified with benzaldehyde and cross-linked with glutaraldehyde (CB), its hydrophobicity increases, hence the sorption affinity to hydrophobic hydrocarbons. Including in situ synthesized zinc oxide particles in the hydrophobic chitosan layer (CBZ) changes its structure and increases the sorption capacity. The morphology of the layers was assessed using scanning electron microscopy (SEM) and by comparing the contact angles of the pollutants against the cotton fabric and the composite materials. EDX analysis and mapping for the Zn element show that zinc is homogeneously distributed on the fabric surface. The roughness enhancement and mesoporous structure under the influence of zinc oxide particles were established by the Brunauer Emmett Teller (BET) method and atomic force microscopy (AFM). The advantages of textile composites are their flexibility, stability, and ability to float on the water and wipe up oil spills. It was found that the materials can be successfully regenerated and used repeatedly, making them highly effective because the sorbed crude oil or petroleum products can be separated and utilized. Full article

Biomolecular adsorption has great significance in medical, environmental, and technological processes. Understanding adsorption equilibrium and binding kinetics is essential for advanced process implementation. This requires identifying intrinsic determinants that predict optimal adsorption properties at bio–hybrid interfaces. Solid-binding peptides (SBPs) have targetable intrinsic properties involving peptide–peptide and peptide–solid interactions, which result in high-affinity material-selective binding. Atomic force microscopy investigations confirmed this complex interplay of multi-step peptide assemblies in a cooperative modus. Yet, most studies report adsorption properties of SBPs using non-cooperative or single-step adsorption models. Using non-cooperative kinetic models for predicting cooperative self-assembly behavior creates an oversimplified view of peptide adsorption, restricting implementing SBPs beyond their current use. To address these limitations and provide insight into surface-level events during self-assembly, a novel method, the Frequency Response Cooperativity model, was developed. This model iteratively fits adsorption data through spectral analysis of several time-dependent kinetic parameters. The model, applied to a widely used gold-binding peptide data obtained using a quartz crystal microbalance with dissipation, verified multi-step assembly. Peak deconvolution of spectral plots revealed distinct differences in the size and distribution of the kinetic rates present during adsorption across the concentrations. This approach provides new fundamental insights into the intricate dynamics of self-assembly of biomolecules on surfaces. Full article

Nanoparticles are known to have a high specific surface area, which accounts for an increased probability of their interaction with bacterial cells. Therefore, the application of silver(I) nanoparticles (AgNPs) and their nanocomposites as antimicrobial agents against drug-resistant bacterial strains appears to be prospective. A critical point for the advancement of AgNPs into clinical practice is a fundamental understanding of their behavior in biological systems, including protein binding and interaction with blood components, which reflects their toxicity. The latter is primarily determined by the physicochemical properties of AgNPs, namely their size, shape, surface chemistry, etc. Therefore, nanotoxicity may be substantially reduced through the manipulation of certain physicochemical characteristics of AgNPs, increasing their biocompatibility and hence paving the way for possible biomedical applications. In this study we have focused on estimating the binding affinity of the synthesized Ag(I) complexes of 2-(4,6-di-tert-butyl-2,3-dihydroxyphenylsulfanyl)-acetic acid and 4,6-di-tert-butyl-2,3-dihydroxybenzaldehyde isonicotinoyl hydrazone, as well as AgNPs derived thereof to bovine serum albumin (BSA) and hemoglobin by the fluorimetric method. Furthermore, cellular toxicity of the AgNPs towards human erythrocytes was measured in a hemolysis assay. Organosols formed by the Ag(I) complexes upon their reduction to AgNPs in acetonitrile and DMSO were characterized by the transmission electron microscopy (TEM) method and atomic force microscopy (AFM). Full article

To obtain versatile nanoplatforms comparable for various bio-applications, synthesis and functionalization of two inorganic nanoparticles (NPs), i.e., gold (AuNPs) and iron oxide (SPIONs), are described for different NP diameters. Chosen ligands have adapted chemical function to graft to the surfaces of the NPs (thiols and phosphonates, respectively) and the identical frequently used external carboxyl group for comparison of the NPs’ material effect on their final behavior. To further evaluate molecular length effect, AuNPs are functionalized by different ligands. Numerous characterizations highlight the colloidal stability when grafting organic molecules on NPs. The potentiality of the functionalized NPs to react efficiently with a protein monolayer is finally evaluated by grafting them on a protein covered chip, characterized by atomic force microscopy. Comparison of the NPs’ surface densities and measured heights enable observation of different NPs’ reactivity and infer the influence of the inorganic core material, as well as the NPs’ size and ligand length. AuNPs have higher affinities to biomolecules, especially when covered by shorter ligands. NP ligands should be chosen not only based on their length but also on their chemical chain, which affects proteic layer interactions. This original multiplex comparison method using AFM is of great interest to screen the effects of used NP materials and functionalization when developing theranostic nanoplatforms. Full article