Search Results (579)

Basidiomycete mushrooms contain complex β-D-glucans which act as immunomodulator, immune stimulants and anti-cancer agents, which can be either free or bound to proteins. The present report consists of a novel and intrinsic synchronous fluorescence and phosphorescence assay method for β-D-glucans. This analytical technique was carried out by a spectrofluorometer in the range of 250 to 750 nm with a Δλ range of 5–30 nm which exhibited peaks at 492, 540 and 550 nm by using β-D-glucan from Euglena gracilis as a standard. A micro and high-throughput method based on a microplate fluorescence reader was devised with a excitation and emissions λ of 420 nm and 528 nm, respectively. This assay method revealed some advantages over the reported colorimetric methods, since it is a non-destructive assay method of β-D-glucans in samples with a linearity range of 0–14 μg/well, correlation coefficient (r2) of 0.9961, LOD of 0.973 μg/well, LOQ of 2.919 μg/well, greater sensitivity, fast, a high-throughput method and very economical. β-D-glucans of several mushrooms (i.e., Poria coccus, Auricularia auricula, Ganoderma lucidium, Pleurotus ostreatus, Cordyceps sinensis, Agaricus blazei, Polyporus umbellatus, Inonotus obliquee) were purified by using a sequence of various solvent extractions, quantified by either spectrofluorometer or fluorescence microtiter plate reader assay and compared with Congo red assay method. Three-dimensional spectra measurements were carried out on β-D-glucans from commercial sources and medicinal mushroom strains. FTIR spectroscopy was selected to investigate the structural properties of β-D-glucans in these mushroom samples. Therefore, the present assay method is simple, fast, cheap and non-destructive for β-D-glucans from medicinal mushrooms as well as from commercial sources. Full article

The solid structure of industrial sinter comprises seven mineral associations (A, B, C, D, Ds, E, N) which have different relative abundances of key minerals, textures and spatial relationships to micro-macropores and hematite nuclei. Among the key characteristics of the mineral associations: (MA), MA-A comprises abundant SFCA-I microplates with hematite; MA-B consists of disseminated fine-grained magnetite in a network of SFCA-III microplates; MA-C is similar to MA-B but contains patches of dendritic SFCA-III with larnite and minor glass; MA-D comprises magnetite surrounded by coarse prisms of SFCA within glass; MA-Ds, a subtype of MA-D, includes SFCA with secondary skeletal hematite; MA-E consists of anhedral to skeletal magnetite or hematite in a matrix of glass; and MA-N comprises unmelted hematite nuclei from iron ore feedstock. SFCA-III and SFCA-I are dominant in MA-B and MA-A, respectively, whilst magnetite is the most common mineral in MA-C, MA-D/Ds and MA-E. Low-temperature sintering samples are largely of MA-A to MA-D (62 area %), which contain higher combined levels of SFCA-SFCA-III and lower levels of magnetite-dominant MA-E (12.6 area %), whereas high-temperature/magnetite sintering examples had high levels of magnetite-dominant MA-E (31.6 area %) and MA-D/Ds (52.1 area %) and low levels of MA-A to MA-C (8.9 area %). It is proposed that the formation of each MA is controlled by the peak sintering temperature attained, the dwell time at higher temperature which adversely allows fractional crystallisation to tie up more Fe in magnetite rather than forming SFCA phases during cooling, and especially a slower rate of cooling which promotes the formation of more SFCA family phases at lower temperatures. However, local variations in chemistry inherited from raw material granulation and assimilation during sintering of Si-rich gangue or ore nuclei are also important. Full article

The reliance on unstable hydrogen peroxide (H₂O₂) adversely affects the robustness and simplicity of chemiluminescence (CL)-based immunoassays. We report a novel external H₂O₂-free Fenton CL system integrated into a highly sensitive non-enzymatic immunoassay for the detection of SARS-CoV-2 nucleoprotein, utilizing cuprous–polyethylenimine–lipoic acid nanoflowers (Cu(I)-PEI-LA-Ab NF) as a non-enzymatic tag. The signaling polymer (PEI-LA) was synthesized via EDC/NHS coupling, which conjugated approximately 550 LA units to the PEI backbone. This polymer formed antibody-conjugated NF with various metal ions, and the Cu(I)-based variant was selected for its intense and sustained CL with luminol. The mechanism relies on an in situ Fenton reaction, in which dissolved oxygen is reduced by Cu(I) to H₂O₂, which reacts with oxidized Cu(II), producing hydroxyl radicals that oxidize luminol. Direct calibration of the SARS-CoV-2 nucleoprotein fixed on microplate wells demonstrated excellent linearity in the range of 0.01–3.13 ng/mL (LOD = 3 pg/mL). In a final competitive immunoassay format for samples spiked with the antigen, a decreasing CL signal that correlated with increasing antigen concentration was obtained in the range of 0.1–20.0 ng/mL, achieving excellent recoveries that were favorable compared with those of the sandwich ELISA kit, establishing this H₂O₂-independent platform as a powerful and robust tool for clinical diagnostics. Full article

As a convergent zone of multiple plates, the Caribbean Sea and its adjacent areas have experienced a complex tectonic evolution process and are characterized by prominent microplate development. This region provides a natural laboratory for studying the formation mechanism of continental margins, the evolution process of ocean basins, and the tectonics of microplates. However, the crustal structure and microplate tectonics in this region remain unclear due to limitations of conventional planar gravity inversion methods, which neglect the Earth’s curvature in large-scale areas, as well as the uneven coverage of regional seismic networks. To precisely delineate the crustal structure and microplate boundaries in the Caribbean Sea region, this study employs a nonlinear gravity inversion method based on a spherical coordinate system. By utilizing GOCO06s satellite gravity data, ETOPO1 topographic data, and the CRUST1.0 crustal model, we performed inversion calculations for the Moho depth in the Caribbean Sea and its adjacent regions and systematically analyzed the crustal structure and microplate tectonic characteristics of the region. The results indicate that the gravity inversion method in the spherical coordinate system has good applicability in complex tectonic regions. The inversion results show that the Moho depth in the study area generally presents a spatial distribution pattern of “shallow in the central part and deep in the surrounding areas”. Among them, the Moho depth is the largest (>39 km) at the junction of the Northern Andes and the South American Plate, while it is relatively shallow (<6 km) in regions such as the Cayman Trough, the Colombian Basin, and the Venezuelan Basin. Based on the Moho undulation, gravity anomalies, and topographic features, this study divides the Caribbean Sea and its adjacent areas into 22 microplates and identifies three types of microplates, including oceanic, continental, and accretionary. Among them, there are 10 microplates with oceanic crust, 6 with continental crust, and 5 with accretionary crust, while the Northern Andes Microplate exhibits a mixed type. The crustal structure characteristics revealed in this study support the Pacific origin model of the Caribbean Plate, indicating that most of the plate is a component of the ancient Pacific Plate with standard oceanic crust properties. Locally, the Caribbean Large Igneous Province developed due to hotspot activity, and the subsequent eastward drift and tectonic wedging processes collectively shaped the complex modern microplate tectonic framework of this region. This study not only reveals the variation pattern of crustal thickness in the Caribbean Sea region but also provides new geophysical evidence for understanding the lithospheric structure and microplate evolution mechanism in the area. Full article

Nanomaterials are widely used in biomedical research as drug and antibody carriers, and some nanomaterials have been shown to exhibit antimicrobial activity. Previously, silver nanoclusters (AgNCs) were predicted to interact with the bacterial TolC protein, which is involved in the development of multidrug resistance in pathogens. In this study, glutathione-coated AgNCs were synthesized and characterized. Their toxicological properties were studied in a microplate assay against five bacterial strains, both as single components and in mixtures with heavy metal salts and antibiotics. The resulting AgNCs had a diameter of 2.2 ± 0.5 nm, with excitation and emission maxima of λ = 490 nm and λ = 638 nm, respectively. No significant growth inhibition was observed at the concentrations used in resistance modulation assays (≤2.5 µg/mL Ag), except for transient effects at very high concentrations. A decrease in bacterial resistance to copper (II) and cadmium (II) cations and the antibiotics erythromycin and levofloxacin was observed upon the addition of AgNCs containing 2.5 μg/mL silver to the nutrient medium. A dose-dependent effect of AgNCs on bacterial resistance to toxicants was established. Thus, nanoclusters can be considered as inhibitors of bacterial resistance to heavy metals and antibiotics, which may be useful in studying bacterial adaptation mechanisms and developing technologies for overcoming multidrug resistance in bacteria. Full article

Background/Objectives: The timely evaluation of blood clot formation and breakdown is essential in the care of patients with severe bleeding or critical illness. Resonant acoustic rheometry is a novel, non-contact ultrasound method that measures changes in the viscoelastic properties of blood in a standard microplate format. Here, we present the first clinical description of whole blood coagulation and fibrinolysis assessed with resonant acoustic rheometry, with paired thromboelastography measurements for comparison. Methods: In this retrospective analysis, whole blood samples from three critically ill patients were divided and tested under four different conditions that included a control mixture, kaolin activation, tissue factor activation, and a tissue factor mixture supplemented with tissue plasminogen activator. The resonant acoustic rheometry system obtained real time measurements of resonant surface waves and displacements from the samples. Heat maps and spectrograms of the resonant surface waves were analyzed to determine the onset of clotting, the rate of viscoelastic stiffening, the time to maximum rigidity, and the onset as well as magnitude of fibrinolysis. These measurements were compared with thromboelastography reaction time, clot strength, fibrinogen contribution, and lysis values. Results: Resonant acoustic rheometry detected reproducible transitions from liquid to clot and from clot to lysis in all samples. Activator-dependent changes in clot initiation and propagation matched the expected hierarchy observed in thromboelastography. Significantly, samples exposed to tissue plasminogen activator demonstrated a clear fall in resonant frequency and a corresponding rise in surface displacement that reflected fibrinolysis. The technique also reproduced clinically meaningful patterns of hemostasis that aligned with each patient’s underlying disease. Conclusions: Whole blood clotting can be measured with resonant acoustic rheometry in a manner that aligns with established clinical assays. These results suggest strong potential for future use of resonant acoustic rheometry as a cost-effective, complementary platform for rapid, scalable, and clinically informative hemostatic assessment. Full article

Quantifying low-molecular-mass (LMM) flavanols in wines is relevant because these compounds, though typically minor, reflect flavanol structural composition (seed vs. skin contributions) and relate to cultivar and winemaking technique. Their determination is challenging because oligomeric and polymeric tannins interfere with standard spectrophotometric assays. This study introduces a coupled procedure that isolates and selectively quantifies LMM flavan-3-ols by combining the well-established methylcellulose precipitation assay (MCP) to remove oligomers and polymers with dimethylaminocinnamaldehyde (DMAC) determination of the MCP supernatant. The sequential workflow uses DMAC specificity and sensitivity and minimizes interference caused by higher-mass flavanols. Additionally, samples are quantified following dilution in the highly stable MCP supernatant medium. A Small Flavanol Index (SFI, %) is also introduced, expressing the LMM fraction relative to methylcellulose-precipitable tannins and providing a descriptor of flavanol composition. The method was validated in terms of linearity, limits of detection and quantification (LOQ in the supernatant, 1.58 mg L⁻¹), precision, and recovery. Applicability is demonstrated in Marselan and Tannat (Vitis vinifera), resolving compositional differences by cultivar, grape tissue (skins vs. seeds), and maceration technique. Compatible with microplate formats and simple instrumentation, this robust analysis enables tandem determination of LMM flavanols and condensed tannins and represents an analytically valuable tool for commercial wineries and research. Full article

Background/Objectives: Regardless of the underlying cause, wound infections are among the most common complications associated with wound formation. The increasing prevalence of antibiotic resistance poses significant challenges in wound management. Due to their favorable therapeutic properties, alginate films have recently emerged as promising biomaterials for wound treatment. Methods: The petroleum ether, chloroform, and methanol extracts of the endemic plant Stachys rupestris were prepared using the maceration technique. The antimicrobial activity of the extracts and the extract-loaded alginate film was evaluated by agar well diffusion and microdilution assays, while their antibiofilm activity was assessed by crystal violet staining in microplates. The anti-infective potential was investigated using the Caenorhabditis elegans infection model, the phytochemical composition was analyzed by HPLC-DAD, and cytotoxicity was determined by the MTT assay. The alginate film was prepared by the solvent casting method and characterized using FTIR spectroscopy and light microscopy. Results: All extracts demonstrated antimicrobial activity, with the methanol extract exhibiting the most potent antimicrobial and antibiofilm effects. Quinic acid was identified as the major constituent. Both the methanol extract and the film displayed no cytotoxic effects and showed significant antimicrobial and antibiofilm activities. Conclusions: The S. rupestris methanol extract-loaded film exhibited strong antimicrobial and antibiofilm properties, indicating its potential as a valuable therapeutic agent in supporting wound healing. Full article

This study validates green hydrogen (${\mathrm{H}}_2$) production from a 15 kWe wind–solar PV microplant under real operating conditions and quantifies the renewable diesel (RD) potential from oil hydroprocessing (with palm oil as the base case) via detailed stoichiometric balances. The electric output feeding two electrolyzers was monitored for six months (December 2024–May 2025). Three ${\mathrm{H}}_2$ production models were calibrated against the experimental results; the model with the best fit achieved ${\mathrm{R}}^2$ = 0.9848 and MSE = 130.05. Using the estimated ${\mathrm{H}}_2$ production, monthly balances were established for palm oil TAGs (POP, POO, POL, PLP, and SOS) across various deoxygenation routes—namely decarboxylation (DCX), decarbonylation (DCN), and hydrodeoxygenation (HDO)—with coproduct closure (propane, ${\mathrm{CO}}_2/\mathrm{CO}/{\mathrm{H}}_2\mathrm{O}$). The hybrid plant operated above the electrolyzers’ 2.88 kWe minimum, raising the effective ${\mathrm{H}}_2$ output (which peaked in February–March) and, thereby, the RD potential. The specific ${\mathrm{H}}_2$ demand followed the gradient of HDO > DCN > DCX; for POP, the global demand was 0.30 kg (saturation) + 1.20 kg (cracking) + 2.10 kg (DCN) or 2.55 kg (HDO), highlighting the carbon–hydrogen trade-off. The results indicate that ${\mathrm{green-H}}_2$–HDO integration is technically feasible and scalable in La Guajira; the choice of route (DCX/DCN vs. HDO) should align with local renewable availability to either maximize the liters of RD per kg ${\mathrm{H}}_2$ or conserve carbon. Full article

This paper proposes a method for E. coli detection in a microplate format using low-molecular-weight compounds that specifically interact with the lipopolysaccharides (LPSs) of E. coli cell walls. These compounds can amplify analytical signals by binding to multiple repeating cell surface structures, while the selectivity for E. coli is ensured by preliminary cultivation on selective media, such as Endo or MacConkey agar. 3-Aminophenylboronic acid (APBA) was selected as the binding reagent for detecting E. coli LPSs. Conjugates of streptavidin (STP) and bovine serum albumin (BSA) with APBA and conjugates of biotin and soybean trypsin inhibitor (STI) and BSA were synthesized. The conditions for the sequential formation of “sandwich” type complexes (BSA-APBA conjugate/E. coli/STP-APBA/STI–biotin/STP–peroxidase) and their colorimetric detection using chromogenic peroxidase substrate were determined. The detection limit was 3 × 10² cells/mL, and the range of quantitative determination covered five orders of magnitude—from 10³ to 10⁸ cells/mL. The developed assay was successfully tested using inactivated cells of pathogenic E. coli strains, confirming its potential for application. The assay was demonstrated to have universality, with the ability to detect E. coli, other bacterial pathogens, and LPS alone. This method could be adopted for the quantitative determination of different specific bacterial species using different selective media. Full article

It is relevant to develop new technologies to enable the intensive monitoring of kidney function in a minimally invasive, rapid, and economic way. With this goal, the current work compared infrared spectra in the mid- (MIR) and near-infrared (NIR) regions to predict the biomarkers of kidney function, i.e., serum creatinine, urea, and albumin. After the evaluation of diverse spectra pre-processing methods and spectral regions, it was possible to develop, in either spectral region, good to excellent regression models to predict these three biomarkers, with determination coefficients (R²) of over 0.9 and relatively low root mean squared error (RMSE). The two techniques are complementary, since the MIR spectroscopic platform presents the advantage of enabling high-throughput analysis, as it includes the sample analysis based on a micro-plate with 96 wells, only requiring a simple dehydration step before spectra acquisition, while the NIR spectroscopic platform enables the direct analysis of the serum solutions in real time. Therefore, both platforms present complementary characteristics with a high potential to enable reagent-free and frequent monitoring of kidney function and incorporation into point-of-care diagnostic systems. Full article

Glucosinolate-derived metabolites play central roles in plant defense and are increasingly recognized for their pharmacological importance. Barbarea vulgaris produces a structurally diverse set of such compounds, yet their biological activities remain insufficiently explored. In this study, natural metabolites and their synthetic analogues were evaluated for antimicrobial, antibiofilm, antioxidant, and anti-inflammatory properties. Antimicrobial activity was assessed against human and plant pathogens by determining minimum inhibitory and minimum microbicidal concentrations, antibiofilm potential was examined using microplate assays, and radical scavenging activity was measured by DPPH and ABTS assays. In addition, the compounds were screened for inhibitory effects on lipoxygenase (LOX) and cyclooxygenase-2 (COX-2). Phenolic derivatives, particularly methyl-4-hydroxyphenylethyl dithiocarbamate (2) and 2-(4-hydroxyphenyl)ethyl isothiocyanate (8), exhibited notable in vitro antibacterial activity (MIC 0.312–1.25 mg mL⁻¹ against E. coli ATCC 25922 and S. aureus ATCC 25923) and detectable antibiofilm effects. Racemic barbarin (4) preferentially inhibited LOX, underscoring its potential as an anti-inflammatory scaffold, whereas COX-2 inhibition was weak across all tested compounds. None of the metabolites showed radical scavenging activity, suggesting that their effects rely on enzyme inhibition or microbial interactions rather than nonspecific antioxidant mechanisms. This study provides an integrated evaluation of B. vulgaris metabolites, highlighting their ecological role in plant defense and their potential as scaffolds for novel antimicrobial and anti-inflammatory agents. Full article

Mastitis is one of the major diseases affecting dairy cattle worldwide. Antibiotic therapy remains the most widely used treatment. However, its effectiveness has been compromised due to the selection of antibiotic-resistant and biofilm-producing pathogenic bacteria. This promotes the search for alternatives that increase the antibacterial and antibiofilm efficacy of antibiotics such ceftiofur (CFT). Nisin (N) and chitosan (CH) may possess these properties. The aim of this study was to evaluate whether N + CFT and CH + CFT combinations enhance the antibacterial activity of the antibiotic on Staphylococcus aureus associated with bovine mastitis, as well as its antibiofilm effect. Two clinical isolates of S. aureus (AMC-43 and AMC-48) and the reference strain ATCC 27543 resistant to CFT were used. Through the microdilution method in 96-well microplates, the combination of sub-inhibitory concentrations of N (320 µg/mL) and CH (400 µg/mL) with CFT (1, 2, 4, and 8 µg/mL) significantly reduced bacterial growth; however, the CH + CFT mixtures were the most efficient. The crystal violet staining method and live cell plating showed antibiofilm activity in biofilm synthesis and in the reduction in living bacterial cells located inside this preformed structure. These results highlight N and CH as potential agents for the prevention or control of bovine mastitis. Full article

Background: Small-scale food animal production is common worldwide but often underestimated as a source of antimicrobial resistance. This study aimed to determine the prevalence of MRSA and VRE-E. faecium, and ESBL-E. coli bacteria among workers and within the production environment of low-capacity slaughterhouses, as well as to analyze the antimicrobial resistance patterns of these bacteria and their ability to form biofilms. Methods: The measurements were carried out in three low-capacity slaughterhouses in Poland. Bioaerosol samples, swabs from the production environment fomite and carcasses, meat samples, and swabs from workers’ hands and nostrils were taken. The strains’ susceptibility to antibiotics was assessed using the disk diffusion method, and their biofilm-forming potential was assessed using the microplate method. Isolates were also tested for the presence of genes related to biofilm formation and resistance to antiseptics. Results: In this study, 13.8%, 20.5%, and 14.9% of the samples (n = 268) were positive for MRSA, ESBL-E. coli, and VRE-E. faecium, respectively, with the highest detection rates on pork carcasses and surfaces. MRSA and ESBL-E. coli bacteria were also detected in swabs from workers’ hands and nasal swabs, and in bioaerosol samples. Most isolates revealed multidrug resistance, including 89% of MRSA, 76% of ESBL-E. coli, and 83% of VRE-E. faecium. The majority of them were also capable of biofilm formation—81%, 65%, and 75%, respectively—emphasizing their survival capabilities in slaughterhouse environments. Conclusions: The slaughterhouse workers are regularly exposed to antibiotic-resistant bacteria such as MRSA, ESBL-E. coli, and VRE-E. faecium. To reduce these risks, it is essential for small slaughterhouses to strictly follow hygiene protocols, enhance the separation between clean and contaminated areas, improve ventilation, and ensure the use of protective measures. Full article

Oxidative stress reflects an imbalance between pro-oxidants and antioxidants arising from physiological or environmental factors. Here, we applied our previously developed in situ microplate method for the simultaneous determination of antioxidant and pro-oxidant activities to compounds produced by plant cell cultures in vitro. The primary aim was to evaluate the added value of these compounds, which are widely used as additives in food, cosmetic, and pharmaceutical products. The secondary aim was to assess whether a predominance of pro-oxidant activity could limit their biotechnological production. Thirty-three compounds known to be produced by in vitro cultures (polyphenolic acids, flavonoids, quinones, alkaloids, etc.) were tested, and the pro-oxidant–antioxidant balance index (PABI) was calculated. Sixteen compounds showed measurable activities with DPPH₅₀/FRAP₅₀ values below 2 mM. Within this set, rosmarinic acid exhibited pronounced pro-oxidant behavior, whereas gallic acid, chlorogenic acid, and the anthocyanin cyanidin showed higher antioxidant potency and favorable PABI values. Such compounds may deliver added benefits when incorporated into food or cosmetic products and are unlikely to limit production in cell culture. Full article