Search Results (1,700)

In recent years, metal nanoclusters (NCs) with atomic-scale precision have emerged as novel photosensitizers for light energy conversion in metal cluster-sensitized semiconductor (MCSS) systems. However, conventional NCs often suffer from photodegradation after binding with semiconductors, limiting their long-term catalytic stability. Modifying NCs via single-atom doping provides an effective strategy to tailor their interfacial charge transfer behavior. In this study, PtAg₂₈ NCs were synthesized by doping Pt single atoms into Ag₂₉ NCs and subsequently loaded onto TiO₂ via electrostatic adsorption to construct composite photocatalysts. Systematic investigations revealed that Pt doping significantly enhances light absorption and promotes the formation of a direct Z-scheme heterojunction. The optimized PtAg₂₈/TiO₂ composite exhibits effective suppression of charge recombination. This enhanced charge separation efficiency, driven by pronounced band bending at the interface, leads to a remarkable hydrogen evolution rate of 14,564 μmol g⁻¹ h⁻¹. This work demonstrates the critical role of single-atom doping in regulating the photophysical properties of metal NCs and offers a feasible approach for designing highly efficient and stable metal-cluster-based photocatalytic systems. Full article

Background/Objectives: Bacterial outer membrane vesicles (OMVs) play a role in bacterial communication, virulence, antimicrobial resistance, and host–pathogen interaction. OMV isolation is a key step for studying these particles’ functions; nevertheless, isolation procedures can greatly influence the yield, purity, and structural integrity of OMVs, thereby affecting downstream biological analyses and functional interpretation. Methods: In this study, we compared the efficacy of two OMV isolation techniques, differential ultracentrifugation (dUC) and size-exclusion chromatography (SEC), in separating and concentrating vesicles produced by two Escherichia coli strains belonging to uropathogenic (UPEC) and Shiga toxin-producing (STEC) pathotypes. The isolated OMVs were characterized using a multi-analytical approach including transmission and scanning electron microscopy (TEM, SEM), nanoparticle tracking analysis (NTA), dynamic light scattering (DLS), ζ-potential measurement, and protein quantification to assess the purity of the preparations. Results: Samples obtained by dUC exhibited higher total protein content, broader particle size distributions, and more pronounced contamination by non-vesicular material. In contrast, SEC yielded morphologically homogeneous and structurally well-preserved vesicles, higher particle-to-protein ratios, and lower total protein content, reflecting reduced co-isolation of protein aggregates. NTA and DLS analyses revealed polydisperse populations in samples obtained with both isolation methods, with DLS measurements highlighting the contribution of larger or transient aggregates. ζ-potential values were close to neutrality for all samples, consistent with limited electrostatic repulsion and with the aggregation tendencies observed in some preparations. Conclusions: This study describes features of OMV produced by two relevant E. coli strains considering two isolation strategies which exert method- and strain-dependent effects on vesicle properties, including size distribution and surface charge, and emphasizes the trade-offs between yield, purity, and vesicle integrity. Full article

The escalating global water crisis necessitates the development of efficient, sustainable, and cost-effective remediation technologies. This review highlights bentonite–sawdust-derived carbon composites as a promising class of adsorbents for the removal of diverse water pollutants. The synthesis strategies, physicochemical properties, key interfacial adsorption mechanisms, and adsorption performance toward different pollutant categories are systematically discussed. These hybrid materials exhibit synergistically enhanced properties, including increased surface area, optimized porosity, abundant functional groups, tunable surface charge, and improved structural stability, often outperforming the individual components. Their effectiveness has been demonstrated for both heavy metals (e.g., Cd and Pb) and organic contaminants (e.g., dyes and pharmaceuticals), governed by a combination of ion exchange, electrostatic attraction, π–π interactions, and pore-filling mechanisms. Current challenges related to large-scale production, long-term stability, and regeneration are critically evaluated, and future research directions for the sustainable application of these composites in advanced water treatment systems are outlined. Full article

The Planting Oysters to Strengthen the Foundation (POSF) method, as a construction technique for coastal stone structures in the Northern Song Dynasty of China (1059), has been preserved to this day. Exploring its long-term reinforcement mechanism can provide theoretical support and practical guidance for the protection and sustainable development of world marine cultural heritage. This article uses Crustacean Ash Triad Clay (CATC) from Shihu Ancient Wharf in Quanzhou as a case study and conducts a systematic investigation using XRD, Raman, SEM-EDS, FTIR, and 16S rRNA high-throughput sequencing. The results show that CATC has a core skeleton of 94.6% quartz, with potassium feldspar, dolomite, and metal compounds as auxiliary components; that its 19.04% porosity provides enrichment space for positively charged ions and tide-borne microorganisms; that electrostatic adsorption between barnacle adhesive and the material achieves physical reinforcement; and that microbial metabolism promotes dolomite formation, producing chemical reinforcement. Thus, the ternary coupling of Biology–Environment–Materials forms a BEM long-term reinforcement mechanism suitable for low-carbon construction in the ocean. Full article

The widespread occurrence of pharmaceutical residues in aquatic environments necessitates the development of advanced porous materials for efficient remediation. This study investigates the adsorption mechanisms of ibuprofen and atenolol within the high-silica zeolite Y. Batch adsorption experiments demonstrated significant uptake, with loading capacities of 191.6 mg/g for ibuprofen and 273.0 mg/g for atenolol, confirming the material’s effectiveness. Using a combination of neutron and X-ray powder diffraction, complemented by Rietveld refinement and simulated annealing algorithms, we achieved the exact localization of the guest molecules. While the pristine zeolite maintains cubic symmetry $Fd\overline{3}$, the incorporation of pharmaceutical molecules induces significant residual nuclear density and anisotropic lattice distortions. To accurately model these perturbations, a systematic symmetry reduction to the acentric triclinic space group F1 was implemented. This approach enabled an ab initio refinement of the structure, revealing that drug uptake of each guest is governed by distinct chemical drivers. Ibuprofen is stabilized via steric confinement and long-range dispersive interactions. In contrast, atenolol stability is governed by electrostatic charge compensation within the zeolitic voids. Our results suggest that the final adsorption geometry is dictated by the spatial orientation of functional groups and host–guest proximity rather than molecular chirality. These results provide a microscopic model describing the fundamental host–guest interactions in FAU zeolites. This structural understanding is an essential step towards the potential use of zeolitic materials in environmental remediation and complex guest sequestration. Full article

Energetic powder processing includes comminution, sieving, drying, conveying, mixing, and packaging, all of which determine product performance and safety. With growing requirements for efficiency and reliability, numerical simulation has become essential for analyzing mechanisms, optimizing parameters, and supporting equipment design. This review summarizes recent progress in simulation techniques such as the discrete element method (DEM), computational fluid dynamics (CFD), and multi-scale coupling while also evaluating their predictive capabilities and limitations across various unit operations and safety concerns such as electrostatic hazards. It, thus, establishes the core “property–parameter–performance” relationships and clarifies mechanisms in multiphase flow, energy transfer, and charge accumulation, and highlights the role of symmetry in improving simulation efficiency. By highlighting persistent challenges, this work lays a foundation for future research, guiding the development of theoretical frameworks and practical solutions for advanced powder processing. Full article

Background/Objectives: Bacterial biofilms formed by Escherichia coli pose a significant challenge in veterinary medicine due to their intrinsic resistance to antibiotics. Antimicrobial peptides (AMPs) represent a promising alternative. AMPs exert their bactericidal activity by binding to negatively charged phospholipids in bacterial membranes via electrostatic interactions, leading to membrane disruption and rapid cell lysis. Methods: In vitro assays including MIC determination, biofilm eradication testing (crystal violet, colony counts, and CLSM), swimming motility, and EPS quantification were performed. CRISPR/Cas9 was used to construct and complement a kduD mutant. A transposon mutagenesis library was screened for biofilm-defective mutants. In an in vivo murine excisional wound infection model treated with the mouse cathelicidin-related antimicrobial peptide (CRAMP-34), wound closure and bacterial burden were monitored. Gene expression changes were analyzed via RT-qPCR. Results: CRAMP-34 effectively eradicated pre-formed biofilms of a clinically relevant, porcine-origin E. coli strain and promoted wound healing in the murine infection model. We conducted a genome-wide transposon mutagenesis screen, which identified kduD as a critical gene for robust biofilm formation. Functional characterization revealed that kduD deletion drastically impairs flagellar motility and alters exopolysaccharide production, leading to defective biofilm architecture without affecting growth. Notably, the anti-biofilm activity of CRAMP-34 phenocopied aspects of the kduD deletion, including motility inhibition and transcriptional repression of a common set of biofilm-related genes. Conclusions: This research highlights CRAMP-34 as a potent anti-biofilm agent and unveils kduD as a previously unrecognized regulator of E. coli biofilm development, which is also targeted by CRAMP-34. Full article

Silica-based sorbents covalently modified with polyhedral boron clusters represent a promising platform for highly selective separation materials, yet robust and synthetically accessible immobilization protocols remain underdeveloped. In this work, novel sorbents based on commercially available silica gels functionalized with closo-dodecaborate anions were synthesized and systematically characterized. Two immobilization strategies were compared: direct nucleophilic addition of surface aminopropyl groups to the nitrilium derivative (Bu₄N)[B₁₂H₁₁NCCH₃] and sol–gel condensation of a pre-formed boron-containing APTES-derived silane. Covalent attachment via amidine bond formation was confirmed by solution and MAS ¹¹B NMR spectroscopy, IR spectroscopy, elemental analysis/ICP-OES, and SEM. The direct grafting route afforded a boron loading of 4.5 wt% (≈20% of the theoretical capacity), with the efficiency limited by electrostatic repulsion between anionic amidine fragments on the negatively charged silica surface, whereas the APTES route gave lower absolute loading (0.085 mmol/g) due to the low specific surface area of the coarse silica support. Despite the moderate degree of functionalization, the resulting boron cluster–modified silica gels are attractive candidates for specialized chromatographic applications, where the unique hydrophobic and dihydrogen-bonding properties of closo-dodecaborates may enable selective retention of challenging analytes and motivate further optimization of surface morphology and immobilization conditions. Full article

Cancer immunotherapy increasingly relies on nucleic acid-based vaccines, yet achieving efficient and safe delivery remains a critical limitation. Polyplexes—electrostatic complexes of cationic polymers and nucleic acids—have emerged as versatile carriers offering greater chemical tunability and multivalent targeting capacity compared to lipid nanoparticles, with lower immunogenicity than viral vectors. This review summarizes key design principles governing polyplex performance, including polymer chemistry, architecture, and assembly route—emphasizing microfluidic fabrication for improved size control and reproducibility. Mechanistically, effective systems support stepwise delivery: tumor targeting, cellular uptake, endosomal escape (via proton-sponge, membrane fusion, or photochemical disruption), and compartment-specific cargo release. We discuss therapeutic applications spanning plasmid DNA, siRNA, miRNA, mRNA, and CRISPR-based editing, highlighting preclinical data across multiple tumor types and early clinical evidence of on-target knockdown in human cancers. Particular attention is given to physiological barriers and engineering strategies—including size-switching systems, charge-reversal polymers, and tumor-penetrating peptides—that improve intratumoral distribution. However, significant challenges persist, including cationic toxicity, protein corona formation, manufacturing variability, and limited clinical responses to date. Current evidence supports polyplexes as a modular platform complementary to lipid nanoparticles in selected oncology indications, though realizing this potential requires continued optimization alongside rigorous translational development. Full article

Nanoparticles interact dynamically with proteins, often leading to adsorption-induced conformational changes that alter protein function and contribute to corona formation. Here we investigated the adsorption and unfolding of a model protein GB1 on latex nanoparticle surfaces using a combination of mutational analysis, equilibrium binding assays, stopped-flow kinetics and Φ-value interpretation. Seven site-directed variants of GB1 were studied to dissect residue-specific contributions to adsorption energetics. Fluorescence binding isotherms revealed that D46A and T53A mutations weakened surface affinity, while kinetic analysis demonstrated that D46A reduced adsorption rate by ~6-fold and produced a dramatic unfolding/refolding shift, identifying Asp46 as a key docking site. Φ-value analysis further highlighted Asp46 and Thr53 as central residues in the adsorption transition state, whereas mutations in the hydrophobic core or distal loops had negligible effects. These results support a dock–loosen–unfold mechanism in which electrostatic recognition initiates binding, followed by hydrophobic exposure and hairpin stabilization. This residue-level sampling of key sites advances mechanistic understanding of protein–nanoparticle interactions and suggests strategies for tuning surface charge to control corona formation. Our approach provides a generalizable method to map adsorption transition states, with implications for designing safer nanomaterials, predicting protein corona composition, and harnessing protein unfolding in biosensing applications. Full article

Smart packaging is an alternative that may not only replace plastic containers, but also enable food quality monitoring. In this study, an innovative packaging system was developed using a starch-chitosan polymer matrix, infused with rosemary essential oil (REO) as an antimicrobial agent, and betalain extract as a food quality indicator. Betalain extract, derived from beet waste, can change color with pH, making it a useful natural indicator for monitoring food freshness. This packaging system is beneficial for foods that produce metabolites related to degradation, which alter pH and allow for the visual detection of changes in product quality. The objective of this work was to develop a smart packaging system with betalains and rosemary essential oil (REO) to extend food shelf life and monitor quality during storage. REO demonstrated antimicrobial activity, but its effect did not differ significantly among the microorganisms tested. On the other hand, the betalain extract (35.75% BE v/v) completely inhibited the growth of Listeria innocua and Salmonella spp. at concentrations of 50% (v/v; 0.82 ± 0.04 mg betalain/g), showing its potential as an antimicrobial agent. The interactions between chitosan and betalains were primarily associated with electrostatic interactions between the positively charged amino groups of chitosan and the negatively charged carboxyl groups of betalains. In contrast to starch, these interactions could result from interactions between the C=O groups of betalain carboxyls and water, which, in turn, interact with the hydroxyl groups of starch through hydrogen bonding. Despite the results obtained in this study, certain limitations need to be addressed in future research, such as the variability in antimicrobial activity among different bacterial strains, which could reveal differences in the efficacy of betalains and essential oils against other pathogens. Full article

Particle-in-Cell (PIC) simulations require accurate solutions of the electrostatic Poisson equation, yet accuracy often degrades near irregular Dirichlet boundaries on Cartesian meshes. While prior work has focused on left-hand-side (LHS) discretization errors, the impact of right-hand-side (RHS) inaccuracies arising from charge deposition near boundaries remains largely unexplored. This study analyzes numerical errors induced by underestimated RHS values at near-boundary nodes when using embedded finite difference schemes with linear and quadratic boundary treatments. Analytical results in one dimension and truncation error analyses in two dimensions show that RHS inaccuracies affect the two schemes in fundamentally different ways: They reduce boundary-induced errors in the linear scheme but introduce zeroth-order truncation errors in the quadratic scheme, leading to larger global errors. Numerical experiments in one, two, and three dimensions confirm these predictions. In two-dimensional tests, RHS inaccuracies reduce the $L_{\infty }$ error of the linear scheme by a factor of 2–3, while increasing the quadratic-scheme error by several times, and in some cases by nearly an order of magnitude, with both schemes retaining second-order global convergence. A simple $\overline{\delta }$-based RHS calibration is proposed and shown to effectively restore the accuracy of the quadratic scheme. Full article

With the rapid development of high-voltage DC (HVDC) power systems, accurate measurement of surface electrostatic potential on insulating components has become critical for electric field assessment and insulation reliability. This paper proposes an electrostatic potential sensor based on cantilever micro-vibration modulation, which employs piezoelectric actuators to drive high-frequency micro-vibration of cantilever-type shielding electrodes, converting the static electrostatic potential into an alternating induced charge signal. An electrostatic induction model is established to describe the sensing principle, and the influence of structural and operating parameters on sensitivity is analyzed. Multi-physics coupled simulations are conducted to optimize the cantilever geometry and modulation frequency, aiming to enhance modulation efficiency while maintaining a compact sensor structure. To validate the effectiveness of the proposed sensor, an electrostatic potential measurement platform for insulating components is constructed, obtaining response curves of the sensor at different potentials and establishing a compensation model for the working distance correction coefficient. The experimental results demonstrate that the sensor achieves a maximum measurement error of 0.92% and a linearity of 0.47% within the 1–10 kV range. Surface potential distribution measurements of a post insulator under DC voltage agreed well with simulation results, demonstrating the effectiveness and applicability of the proposed sensor for HVDC insulation monitoring. Full article

Chlorobaculum tepidum ferredoxin: ${\mathrm{NADP}}^{+}$ oxidoreductase (CtFNR) is a dimeric thioredoxin reductase (TrxR)-type FNR, whose mechanism and redox properties are poorly characterized. In this work, we focused on the reoxidation mechanisms of its flavin adenine dinucleotide (FAD) cofactor using quinones (Q), nitroaromatics (${\mathrm{ArNO}}_2$), and other nonphysiological oxidants with different single-electron reduction midpoint potentials ($E_7^1$) and electrostatic charge. Like in other FNRs, the rate-limiting step of the reaction is the reoxidation of FAD semiquinone (${\mathrm{FADH}}^{•}$). However, only one FAD per dimer functions in CtFNR due to some nonequivalence of the NADP(H) binding domains in separate subunits. The reactivity of Q increases with increasing $E_7^1$, while ${\mathrm{ArNO}}_2$ form another analogous series of lower reactivity. The compounds are reduced in a dominant single-electron way. These data are consistent with an “outer sphere” electron transfer mechanism. On the basis of reactions with 3-acetylpyridine adenine dinucleotide phosphate, the two-electron reduction midpoint potential of FAD at pH 7.0 is −0.282 V. In CtFNR, 11% ${\mathrm{FADH}}^{•}$ was stabilized at equilibrium. Calculated electron transfer distances in reactions with Q and ${\mathrm{ArNO}}_2$ were in the range of 2.6–3.4 Å. Taken together with previous studies of Rhodopseudomonas palustris and Bacillus subtilis FNRs, this work allows us to generalize the information on the catalytic ant thermodynamic properties of TrxR-type FNRs. In addition, our data may be valuable from an applied perspective, e.g., the use of redox mediators in photobioelectrochemical systems or microbial cells based on anoxygenic phototrophic bacteria. Full article

The structure of self-assembled monolayers (SAMs) greatly influences electrochemical interface behavior. This study systematically examines how positional isomers of aromatic diamines (ADMs) assemble on a glassy carbon (GC) electrode and how such ordering affects the attachment and performance of electrochemically reduced graphene oxide (ERGO). SAMs of ortho-, meta-, and para-phenylenediamine (o-PDA, m-PDA, and p-PDA) were fabricated on GC and characterized using atomic force microscopy (AFM) and Raman spectroscopy. Among them, GC/p-PDA exhibited the most compact and homogeneous interfacial structure. ERGO was subsequently immobilized through the free amine functionalities of the SAM, as confirmed by attenuated total reflectance–Fourier transform infrared spectroscopy (ATR-FTIR), X-ray photoelectron spectroscopy (XPS), and cyclic voltammetry (CV). Strong covalent coupling and electrostatic interactions between the positively charged ERGO and terminal amines enabled stable attachment. Under optimized conditions, the modified GC/p-PDA/ERGO electrode demonstrated exceptional electrocatalytic activity toward nitrobenzene (NBz) reduction, achieving a high sensitivity of 1410 μA mM⁻¹ cm⁻² and a low detection limit of 0.040 μM. In addition, this sensor displayed outstanding anti-interference capability, stability, and recovery in a water sample. These results establish GC/p-PDA/ERGO sensor as a robust and efficient electrocatalytically active interface for nitroaromatic pollutants detection and sustainable environmental monitoring. Full article