Search Results (229)

To achieve dual functionality that can monitor both Al³⁺ levels in food and the freshness of fish, rice straw fibers (RSFs) were treated in NaOH solutions and then cationized with 2,3-epoxypropyltrimethylammonium chloride, onto which alizarin red S molecules were immobilized through electrostatic interaction to develop a smart felt-like label. An optimized treatment in 5 wt% NaOH solution effectively removed lignin and hemicellulose, facilitating quaternary ammonium group grafting and stable ARS anchoring. The ARS@BRSF-5NaOH exhibited high pH sensitivity, showing visually discernible color changes (ΔE > 5, perceptible to the naked eye) under acidic (pH ≤ 6) and strongly alkaline (pH > 12) conditions. During the storage of the fish, the label transformed from yellow to dark purple (ΔE increase) as TVB-N levels approached 20 mg/100 g, enabling real-time freshness monitoring for protein-rich products. Additionally, the label achieved a detection threshold of 1 × 10⁻⁵ mol·L⁻¹ for Al³⁺ through a coordination-induced chromatic transition (purple to pale pink). This research highlights the feasibility of utilizing an agricultural waste-derived material to develop cost-effective, visually responsive, dual-functional intelligent labels for food safety, offering significant advancements in on-site quality assessment. Full article

Foam stability plays a critical role in a wide range of industrial and scientific applications. In this study, an innovative method is presented for assessing foam stability through electrical conductivity measurements of liquid films formed within a controlled experimental setup. A modified horizontal glass capillary system with vertically aligned copper electrodes was developed, allowing the continuous monitoring of film drainage and rupture behavior under precise humidity (92% RH) and temperature (30 °C). Experiments were conducted using various concentrations of sodium dodecyl sulfate and Ethylan 1005, with and without NaCl addition. The results demonstrate that film stability increases with higher surfactant concentrations up to a point, beyond which the addition of salt can have either stabilizing or destabilizing effects depending on whether concentration levels are below or above the Critical Micelle Concentration (CMC). At sub-CMC levels, NaCl enhanced film stability by promoting surfactant adsorption and reducing electrostatic repulsion. Conversely, in super-CMC conditions, NaCl led to film destabilization, likely due to changes in interfacial structure and micellar behavior. This approach provides a simple, sensitive, and reproducible technique to quantitatively characterize foam film stability, offering key mechanistic insights and practical guidance for the formulation and optimization of foaming systems across diverse applications. Full article

Conventional conductive hydrogels are susceptible to swelling in aquatic environments; which compromises their mechanical integrity; a limitation that poses a potential challenge to their long-term stability and application. In this study, a zwitterionic ion-conductive hydrogel was fabricated from polyvinyl alcohol (PVA), acrylic acid (AA), and [2-(methacryloyloxy)ethyl]dimethyl-(3-sulfopropyl)ammonium hydroxide (SMBA), forming a dual-network structure. A copolymer of zwitterionic SBMA and AA formed the first network, and PVA formed the second network by repeated freeze–thawing. The equilibrium state of zwitterionic SBMA was modulated by AA to protonate the SBMA, which resulted in the conversion of -SO₃⁻ to -SO₃H; thus, hydrogels had the anti-swelling property driven by electrostatic repulsion. In addition, the prepared hydrogels possessed excellent mechanical properties (tensile strength of 0.76 MPa, elongation at break of 322%, and compressive strength of 0.97 MPa at 75% compressive strain) and remarkable anti-swelling properties (80% swelling after 120 h of immersion). Owing to the zwitterionic nature of SBMA, the hydrogel also showed inherent antimicrobial properties and high electrical conductivity, which could be capable of monitoring human movement and physiological signals. This work provides a facile strategy for designing hydrogels with remarkable mechanical properties and anti-swelling characteristics, expanding the application environment of hydrogels in flexible sensing Full article

Background/Objectives: Burn wound infections present significant clinical challenges due to multidrug-resistant pathogens and the limitations of traditional antimicrobials. While antimicrobial peptides (AMPs) have broad-spectrum effectiveness, their instability in wound environments limits their use. This study compares properties of AMP-decorated nanostructured lipid carriers (NLCs) to free AMPs, focusing on their dermal penetration, retention, and antimicrobial efficacy in simulated ex vivo burn wound models. Methods: AMP-decorated NLCs (smart-AMPs) were produced by electrostatic and hydrophobic surface adsorption and characterized regarding their size, zeta potential, and physical short-term stability. The distribution of AMPs within the wounds was evaluated using an ex vivo porcine ear model with various wound types. The antimicrobial efficacy was assessed by monitoring the bioluminescence of Aliivibrio fischeri as a live bacterial marker for 24 h. Results: The size and zeta potential measurements confirmed the successful formation of smart-AMPs. The dermal penetration of AMPs was influenced by the type of wound and the type of AMP formulation (free AMPs vs. smart-AMPs). In the chronically infected burn wounds, which were characterized by the formation of a biofilm in a protein-rich wound fluid, the smart-AMPs resulted in a 1.5-fold higher and deeper penetration of the AMPs, and the antimicrobial activity was 6-fold higher compared to the free AMPs. Conclusions: smart-AMPs present an innovative approach for treating chronic, biofilm-associated wounds more efficiently than the current treatment options. Full article

Mechanical components are more difficult to detect at the initial state of failure. To solve this problem, this paper models and simulates the characteristics of an electrostatic oil-line sensor (OLS) wear particles carried in the lubricating oil path are detected. In this study, an OLS that monitors the charge in an oil line using the principle of electrostatic induction is modeled and simulated. The sensor characteristics are simulated and tested using finite element simulation. The sensor efficiency, spatial sensitivity, and length-to-diameter ratio are simulated based on the point charges at different locations. The simulation results show that the sensitivity exhibits different trends when the point charge is inside and outside the probe. The length-to-diameter ratio is proportional to the sensor efficiency, the spatial sensitivity distribution law of multiple charges is consistent with that of a point charge, and the relative deviation rate between the mathematically calculated values and the simulated values is less than 3% under the same conditions. In conclusion, the finite element simulation results of the electrostatic oil line sensor constructed in this study are consistent with the theoretical model calculations and can be used in future mechanical fault diagnosis. Full article

Hydrogel sensors show unique advantages in underwater detection, ocean monitoring, and human–computer interaction because of their excellent flexibility, biocompatibility, high sensitivity, and environmental adaptability. However, due to the water environment, hydrogels will dissolve to a certain extent, resulting in insufficient mechanical strength, poor long-term stability, and signal interference. In this paper, a double-network structure was constructed by polyvinyl alcohol (PVA) and poly([2-(methacryloyloxy) ethyl]7 dimethyl-(3-sulfopropyl) ammonium hydroxide) (PSBMA). The resultant PVA/PSBMA-PA hydrogel demonstrated notable swelling resistance, a property attributable to the incorporation of non-covalent interactions (electrostatic interactions and hydrogen bonding) through the addition of phytic acid (PA). The hydrogel exhibited high stretchability (maximum tensile strength up to 304 kPa), high conductivity (5.8 mS/cm), and anti-swelling (only 1.8% swelling occurred after 14 days of immersion in artificial seawater). Assembled as a sensor, it exhibited high strain sensitivity (0.77), a low detection limit (1%), and stable electrical properties after multiple tensile cycles. The utilization of PVA/PSBMA-PA hydrogel as a wearable sensor shows promise for detecting human joint movements, including those of the fingers, wrists, elbows, and knees. Due to the excellent resistance to swelling, the PVA/PSBMA-PA-based sensors are also suitable for underwater applications, enabling the detection of underwater mannequin motion. This study proposes an uncomplicated and pragmatic methodology for producing hydrogel sensors suitable for use within subaquatic environments, thereby concomitantly broadening the scope of applications for wearable electronic devices. Full article

The interaction of cobalt(II) with first-generation quinolones oxolinic acid (Hoxo), flumequine (Hflmq), pipemidic acid (Hppa) and cinoxacin (Hcx) in the presence of the N,N′-donor heterocyclic ligands 2,2′-bipyridine (bipy) or 1,10-phenanthroline (phen) afforded a series of novel cobalt complexes, namely [Co(bipy)₂(oxo)](PF₆)₂·H₂O (1), [Co(phen)₂(oxo)](PF₆)₂·0.5CH₃OH·0.5H₂O (2), [Co(bipy)₂(flmq)](PF₆)₂·0.5CH₃OH·0.5H₂O (3), [Co(bipy)₂(ppa)](PF₆)₂·CH₃OH·0.5H₂O (4), [Co(phen)₂(cx)](PF₆)₂·CH₃OH·0.5H₂O (5), and [Co(phen)₂(flmq)](PF₆)·0.5CH₃OH·H₂O (6). The characterization of the complexes involved physicochemical techniques, various spectroscopies and single-crystal X-ray crystallography. The affinity of complexes to calf-thymus (CT) DNA was monitored with various techniques, suggesting intercalation in-between the DNA-nucleobases as the most probable interaction mode, which may be combined with electrostatic interactions as a result of the cationic nature of the complexes. The affinity of the complexes for bovine and human serum albumin proteins was monitored, and the determined corresponding albumin-binding constants revealed a tight and reversible interaction. Full article

Background: Carob (Ceratonia siliqua L.) pulp flour is primarily used in the food industry. As a rich source of bioactive compounds, particularly polyphenols, it holds promise for pharmaceutical formulation research and development. Objectives: This study focused on developing liposomal particles loaded with carob pulp extract using the proliposome method, followed by modifications through UV irradiation and sonication. Methods: The resulting liposomes were analyzed for encapsulation efficiency, vesicle size, polydispersity index (PDI), mobility, zeta potential, viscosity, surface tension, density, antioxidant activity, FT-IR spectra, and release kinetics under simulated gastrointestinal conditions. In addition, nanoparticle tracking analysis and transmission electron microscopy (TEM) were used for liposomal characterization. Results: The findings revealed a high encapsulation efficiency across all samples (>70%). The particle size and PDI measurements confirmed the presence of a multilamellar and uniform liposomal system before post-processing modifications. The medium value of zeta potential suggested a moderately electrostatically stabilized liposomal suspension. The sonicated liposomes demonstrated a higher concentration of vesicles in comparison to non-treated and UV-irradiated samples. TEM analysis revealed purified liposomal vesicles with preserved structural integrity. Encapsulation, as well as UV irradiation and sonication of liposomes, did not diminish the extract’s anti-DPPH activity. However, the ABTS radical scavenging potential of the pure extract was significantly lower compared to its encapsulated counterparts. UV irradiation and sonication notably reduced the anti-ABTS capacity of the extract-liposome system. Monitoring the release of bioactive compounds demonstrated controlled delivery from liposomal particles under simulated gastrointestinal conditions. Conclusions: Overall, liposomal formulations of carob pulp extract exhibit significant potential for further development as a functional food ingredient or for use in the prevention and treatment of various diseases. Full article

Nitrogen and sulfur-co-doped carbon dots (N, S-CDs) were synthesized using a simple, eco-friendly hydrothermal technique with L-cysteine as the precursor. The synthesis approach produced highly water-dispersible, heteroatom-doped CDs with surface functional groups comprising amine, carboxyl, thiol, and sulfonic acid. Data analysis of X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FT-IR), and transmission electron microscopy (TEM) confirmed their amorphous nature, nanoscale dimensions (1–8 nm, average particle size of 2.6 nm), and surface chemistry. Optical examination revealed intense and pure blue fluorescence emission under UV excitation, with excitation-dependent emission behavior attributed to surface defects and heteroatom doping. The N, S-CDs were applied as fluorescent probes for detecting perfluorooctanesulfonic acid (PFOS), a notable component of the perfluoroalkyl substances (PFAS) family, demonstrating pronounced and concentration-dependent fluorescence quenching. A linear detection range of 3.33–20 µM and a limit of detection (LOD) of 2 µM were reported using the N, S-CDs probe. UV-Vis spectral shifts and dye-interaction investigations indicated that the sensing mechanism is regulated by non-covalent interactions, primarily electrostatic and hydrophobic forces. These findings confirm the potential of N, S-CDs to be used as effective optical sensors for detecting PFOS in environmental monitoring applications. Full article

The proteolytic processing of the SARS-CoV-2 spike glycoprotein by host cell membrane-associated proteases is a key step in both the entry of the invading virus into the cell and the release of the newly generated viral particles from the infected cell. Because of the critical importance of this step for the viral infectivity cycle, it has been a target of extensive efforts aimed at identifying highly specific protease inhibitors as potential antiviral agents. An alternative strategy to disrupt the pre-fusioviden processing of the SARS-CoV-2 S glycoprotein aims to protect the substrate rather than directly inhibit the proteases. In this work, we focused on furin, a serine protease located primarily in the Golgi apparatus, but also present on the cell membrane. Its cleavage site within the S glycoprotein is located within the stalk region of the latter and comprises an arginine-rich segment (SPRRARS), which fits the definition of the Cardin–Weintraub glycosaminoglycan recognition motif. Native mass spectrometry (MS) measurements confirmed the binding of a hexadecameric peptide representing the loop region at the S1/S2 interface and incorporating the furin cleavage site (FCS) to heparin fragments of various lengths, as well as unfractionated heparin (UFH), although at the physiological ionic strength, only UFH remains tightly bound to the FCS. The direct LC/MS monitoring of FCS digestion with furin revealed a significant impact of both heparin fragments and UFH on the proteolysis kinetics, although only the latter had IC50 values that could be considered physiologically relevant (0.6 ± 0.1 mg/mL). The results of this work highlight the importance of the long-range and relatively non-specific electrostatic interactions in modulating physiological and pathological processes and emphasize the multi-faceted role played by heparin in managing coronavirus infections. Full article

Glucose (Glu) detection, as a fundamental analytical technique, has applications in medical diagnostics, clinical testing, bioanalysis and environmental monitoring. In this work, a solid-phase electrochemiluminescence (ECL) enzyme sensor was developed by immobilizing the ECL emitter in a stable manner within bipolar silica nanochannel array film (bp-SNA), enabling sensitive glucose detection. The sensor was constructed using an electrochemical-assisted self-assembly (EASA) method with various siloxane precursors to quickly modify the surface of indium tin oxide (ITO) electrodes with a bilayer SNA of different charge properties. The inner layer, including negatively charged SNA (n-SNA), attracted the positively charged ECL emitter tris(2,2′-bipyridyl)ruthenium(II) (Ru(bpy)₃²⁺) via electrostatic interaction, while the outer layer, including positively charged SNA (p-SNA), repelled it, forming a barrier that efficiently concentrated the Ru(bpy)₃²⁺ emitter in a stable manner. After modifying the amine groups on the p-SNA surface with aldehyde groups, glucose oxidase (GOx) was covalently immobilized, forming the enzyme electrode. In the presence of glucose, GOx catalyzed the conversion of glucose to hydrogen peroxide (H₂O₂), which acted as a quencher for the Ru(bpy)₃²⁺/triethanolamine (TPA) system, reducing the ECL signal and enabling quantitative glucose analysis. The sensor exhibited a wide linear range from 10 μM to 7.0 mM and a limit of detection (LOD) of 1 μM (S/N = 3). Glucose detection in fetal bovine serum was realized. By replacing the enzyme type on the electrode surface, this sensing strategy holds the potential to provide a universal platform for the detection of different metabolites. Full article

In this study, we developed a novel SERS-active magnetic substrate (MBs@CS@AuNPs) for detecting malachite green (MG) in aquatic products, including shrimp, cod, and aquaculture water. The substrate combines chitosan-functionalized magnetic nanobeads with dense gold nanoparticles. It efficiently enriches MG through electrostatic and π–π interactions, generates high-density plasmonic hotspots for stable signals, and utilizes a superparamagnetic core to concentrate MG molecules. This design achieved an ultralow detection limit of 10⁻⁹ M for MG in aquaculture samples, with a linear range spanning from 10⁻³ to 10⁻¹⁰ M (R² = 0.999). The substrate demonstrated superior performance in untreated, complex food matrices (e.g., shrimp, cod), outperforming conventional magnetic mass spectrometry systems that are prone to matrix interference. This work introduces an innovative approach for detecting harmful residues in food during environmental safety monitoring. Full article

Based on density functional calculations, the adsorption and gas sensing properties of transition metal Pt(1-3)-modified TiSe₂ for dissolved gas (CH₄, C₂H₂, CO) in transformer oil were studied in this paper. Firstly, the stable structures, density of states, and energy bands of Pt(1-3)-modified TiSe₂ were calculated. Then, the structure parameters, density of states, electrostatic potential distribution, and desorption time of Pt(1-3)-modified TiSe₂ after adsorbing CH₄, C₂H₂, and CO gas were calculated. The results show that the large binding energy between the transition metal Pt(1-3) modification and the TiSe₂ substrate indicates that the modification systems have good structural stability. On the one hand, Pt(1-3) modification improves the conductivity of TiSe₂. On the other hand, the transition metal Pt(1-3), which acts as the active site for gas adsorption, obviously enhances the gas adsorption effect, resulting in the significant charge transfer and a change in material conductivity. In summary, Pt(1-3)-modified TiSe₂ significantly improves the adsorption and gas sensing performance of gas sensing materials for CH₄, C₂H₂, and CO, which provides a new idea for the study of gas sensing materials for online monitoring of transformer working conditions. Full article

Electrostatic detection is a highly accurate way to monitor system performance failures at an early stage. However, due to the weak electrostatic signal, it can be easily interfered with under complex real-world conditions, leading to a reduction in its monitoring capability. During the electrostatic monitoring of rolling bearings, noise can easily drown out the effective signal, making it difficult to extract fault characteristics. In order to solve this problem, a sparse representation based on cluster-contraction stagewise orthogonal matching pursuit (CcStOMP) is proposed to extract the fault features in the electrostatic signals of rolling bearings. The method adds a clustering contraction mechanism to the stagewise orthogonal matching pursuit (StOMP) algorithm, performs secondary filtering based on atom similarity clustering on the selected atoms in the atom search process, updates the support set, and finally solves the weights and updates the residuals, so as to reconstruct the original electrostatic signals and extract the fault feature components of rolling bearings. The method maintains fast convergence while analysing the extraction effect by comparing the measured signals of rolling bearing outer ring and bearing roller faults with the traditional StOMP algorithm, and the results show that the CcStOMP algorithm has obvious advantages in accurately extracting the fault features in the electrostatic monitoring signals of rolling bearings. Full article

Bees (Hymenoptera, Anthophila) are widely recognized for their essential ecological roles, including pollination and biodiversity maintenance. Recently, their ability to collect environmental particulate matter through electrostatic forces has been explored for biomonitoring purposes. This review integrates knowledge on electrostatic pollen adhesion with emerging insights into particulate matter adhesion to bees, emphasizing their potential as bioindicators. The mechanisms of electrostatic adhesion, influenced by factors such as the physicochemical properties of particulate matter and bee morphology, are discussed in detail. Additionally, the study evaluates the adhesion efficiency of pollutants, including heavy metals, microplastics, nanoplastics, pathogens, pesticides, radionuclides, and volatile organic compounds. This multidisciplinary approach underscores the role of bees in advancing environmental monitoring methodologies and offers innovative tools for assessing ecosystem health while addressing the drivers of bee decline. Full article