Concentration Range Research Articles

Electroanalysis of bromate at riboflavin impregnated Ketjen black porous electrode via an autocatalytic cycle with finite length diffusion

The emergence of elevated concentrations of bromate, classified as a 2B type carcinogen, in drinking water following the treatment of water supplies with ozonation and other oxidation methods has underscored the importance of developing methods for reliable and rapid screening of drinking water. In this work, we report the use of electro activated riboflavin (RF) impregnated Ketjen black (KB) modified screen-printed electrode (elRF@KB-SPE) for the determination of bromate. The sensing surfaces were subjected to morphological and structural characterization using scanning electron microscopy and Raman spectroscopy. These analyses confirmed the successful modification of the electrode with an extended elRF@KB porous coating. Based on cyclic voltammetry (CV) and electrochemical impedance spectroscopy measurements, the response of elRF@KB-SPE towards bromate can be described through a dual mechanism involving i) an autocatalytic chemical/electrochemical process that predominantly occurs in the finite length pores of KB, and ii) an RF-mediated electrocatalytic process. Notably, the data demonstrated that the advanced electrocatalytic properties of the otherwise electrocatalytically inactive absorbed RF molecules are endowed after a simple electro activation process (three CV scans). Amperometric measurements at −0.05V vs. Ag/AgCl revealed a linear relationship between the current response and the concentration of bromates over the concentration range 0.50−18.0μM, achieving a limit of detection (3σ/slope) of 0.04μM. The interference effect of various electroactive species was investigated demonstrating that elRF@KB-SPE is highly selective to bromate. The analytical utility of the method was evaluated in spiked tap water samples. Recoveries were 91.2 − 106.4%.

A Polyacrylate Cotton-based Pipette Tip Micro-solid-phase Extraction Technique Coupled with High-performance Liquid Chromatography for Carvedilol Determination in Aqueous Media

Introduction: In this work, a polyacrylate polymer was synthesized into a pipette tip containing cotton fibers and used to extract carvedilol from water and urine samples. Methods: A high-performance liquid chromatography-ultraviolet detection method was developed, which demonstrated the suitability of the purposed pipette tip micro-solid-phase extraction device. Factors affecting the fabrication procedure and polymer quality were studied and optimized. In the next step, the sample preparation process (including extraction and desorption) was fully optimized, and the optimized method was validated. Results: A coating with suitable mechanical and chemical stability was achieved. Its structure was successfully characterized by Fourier transform infrared spectroscopy and scanning electron microscopy. Within-batch and between-batch fabrication reproducibility were obtained at 3.0 and 9.0 %, respectively. The developed method displayed a limit of detection of 1.1 µg L-1 when 1.5 mL of sample was processed, and it was linear in the concentration range of 3.3-350 µg L-1 with LLOQ of 5 µg L-1 . The polyacrylate cotton-based pipette tip was finally used to extract carvedilol from aqueous media with acceptable recoveries of 92-106%. Conclusion: The proposed method is simple and fast and requires low sample volumes. In addition, this method has been evaluated in terms of greenness with three different tools, and the evaluation results with all three tools have shown that this method is one of the green and environmentally friendly methods.

Applicability of QbD-assisted Analytical Method for Simultaneous Detection of Tetrahydrocurcumin and Folic Acid in Developed Nanostructured Lipid Carriers

Aims: Applicability of QbD-assisted analytical method for simultaneous detection of tetrahydrocurcumin and folic acid in developed nanostructured. Background: Diabetic foot ulcer (DFU) is a multifactorial disorder that involves chronic inflammation, oxidative stress and neuropathy. Current treatment therapies involving the use of growth factors and skin substitutes being costly, are out of reach for the majority of patients. The present research explored the usefulness of (5929IN008, application number 202211045937), a combination of tetrahydrocurcumin and folic acid-loaded nanostructured lipidic carriers. Objectives: To develop and validate a QbD-assisted method for simultaneous analysis of tetrahydrocurcumin (THC) and folic acid (FA). Applicability of the above method to determine total drug content (TDC) and entrapment efficiency (EE) of nanostructured lipid carriers (NLCs) loaded THC and FA. Methods: A high-performance liquid chromatographic (HPLC) method was developed, optimized and validated using Box-Behnken design for improved method performance. Chromatographic separation was conducted on a Supelco 250 x 4.6 mm (5 μm) column with optimized mobile phase composition containing tetrahydrofuran: citric acid buffer pH 3.5 (50:50) at a flow rate of 0.4 mL.min-1 and diode array detection between 210 and 360 nm. Results: The method developed in a concentration range of 1 to 100 μg.mL-1 was found to be linear (R2 0.999, p≤0.001), accurate (99.10-101.70%) and precise with high recovery values in intra and inter-day results. The system adaptability and robustness evaluation revealed that the percent recovery ranged from 96.90 to 102.80%, and the percent relative standard deviation (%RSD) values were less than 2%. Moreover, the method was further applied for the determination of TDC (86±6% and 96±8%) and drug EE (81±21% and 73±13%) for THC and FA, respectively. Conclusion: The investigation indicated the applicability of the developed and validated method for the estimation of THC and FA in the developed nanostructured lipidic carriers.

The effect of DMSO on Saccharomyces cerevisiae yeast with different energy metabolism and antioxidant status

We studied the effect of dimethyl sulfoxide (DMSO) on the biochemical and physiological parameters of S. cerevisiae yeast cells with varied energy metabolism and antioxidant status. The wild-type cells of varied genetic backgrounds and their isogenic mutants with impaired antioxidant defences (Δsod mutants) or response to environmental stress (ESR) (Δmsn2, Δmsn4 and double Δmsn2msn4 mutants) were used. Short-term exposure to DMSO even at a wide range of concentrations (2–20%) had little effect on the metabolic activity of the yeast cells and the stability of their cell membranes, but induced free radicals production and clearly altered their proliferative activity. Cells of the Δsod1 mutant showed greater sensitivity to DMSO in these conditions. DMSO at concentrations from 4 to 10–14% (depending on the strain and genetic background) activated the ESR programme. The effects of long-term exposure to DMSO were mainly depended on the type of energy metabolism and antioxidant system efficiency. Yeast cells with reduced antioxidant system efficiency and/or aerobic respiration were more susceptible to the toxic effects of DMSO than cells with a wild-type phenotype and respiro-fermentative or fully fermentative metabolism. These studies suggest a key role of stress response programs in both the processes of cell adaptation to small doses of this xenobiotic and the processes related to its toxicity resulting from large doses or chronic exposure to DMSO.

Understanding the significance of oxygen tension on the biology of Plasmodium falciparum blood stages: From the human body to the laboratory

Plasmodium falciparum undergoes sequestration within deep tissues of the human body, spanning multiple organ systems with differing oxygen (O2) concentrations. The parasite is exposed to an even greater range of O2 concentrations as it transitions from the human to the mosquito host, suggesting a high level of plasticity as it navigates these different environments. In this review, we explore factors that may contribute to the parasite’s response to different environmental O2 concentrations, recognizing that there are likely multiple pieces to this puzzle. We first review O2-sensing mechanisms, which exist in other apicomplexans such as Toxoplasma gondii and consider whether similar systems could exist in Plasmodium. Next, we review morphological and functional changes in P. falciparum’s mitochondrion during the asexual-to-sexual stage transition and discuss how these changes overlap with the parasite’s access to O2. We then delve into reactive oxygen species (ROS) as ROS production is influenced by O2 availability and oxidative stress impacts Plasmodium intraerythrocytic development. Lastly, given that the primary role of the red blood cell (RBC) is to deliver O2 throughout the body, we discuss how changes in the oxygenation status of hemoglobin, the RBC’s O2-carrying protein and key nutrient for Plasmodium, could also potentially impact the parasite’s growth during intraerythrocytic development. This review also highlights studies that have investigated P. falciparum biology under varying O2 concentrations and covers technical aspects related to P. falciparum cultivation in the lab, focusing on sources of technical variation that could alter the amount of dissolved O2 encountered by cells during in vitro experiments. Lastly, we discuss how culture systems can better replicate in vivo heterogeneity with respect to O2 gradients, propose ideas for further research in this area, and consider translational implications related to O2 and malaria.

Development of Mycobacterium tuberculosis Enoyl Acyl Reductase (InhA) Inhibitors: A Mini-Review

This review article delves into the critical role of Enoyl acyl carrier protein Reductase (InhA; ENR), a vital enzyme in the NADH-dependent acyl carrier protein reductase family, emphasizing its significance in fatty acid synthesis and, more specifically, the biosynthesis of mycolic acid. The primary objective of this literature review is to elucidate diverse scaffolds and their developmental progression targeting InhA inhibition, thereby disrupting mycolic acid biosynthesis. Various scaffolds, including thiourea, piperazine, thiadiazole, triazole, quinazoline, benzamide, rhodanine, benzoxazole, and pyridine, have been systematically explored for their potential as InhA inhibitors. Noteworthy findings highlight thiadiazole and triazole derivatives, demonstrating promising IC50 values within the nanomolar concentration range. The review offers comprehensive insights into InhA's structure, structure-activity relationships, and a detailed overview of distinct scaffolds as effective inhibitors of InhA.

Frequent CHD1 deletions in prostate cancers of African American men is associated with rapid disease progression

We analyzed genomic data from the prostate cancer of African- and European American men to identify differences contributing to racial disparity of outcome. We also performed FISH-based studies of Chromodomain helicase DNA-binding protein 1 (CHD1) loss on prostate cancer tissue microarrays. We created CHD1-deficient prostate cancer cell lines for genomic, drug sensitivity and functional homologous recombination (HR) activity analysis. Subclonal deletion of CHD1 was nearly three times as frequent in prostate tumors of African American than in European American men and it associates with rapid disease progression. CHD1 deletion was not associated with HR deficiency associated mutational signatures or HR deficiency as detected by RAD51 foci formation. This was consistent with the moderate increase of olaparib and talazoparib sensitivity with several CHD1 deficient cell lines showing talazoparib sensitivity in the clinically relevant concentration range. CHD1 loss may contribute to worse disease outcome in African American men.

Eco-friendly electrochemical assay of oxytetracycline and flunixin in their veterinary injections and spiked milk samples

Two solid-contact electrochemical sensors were developed for detection of each of oxytetracycline HCl (OXY), and the co-formulated non-steroidal anti-inflammatory drug flunixin meglumine (FLU) in veterinary formulations and animal-derived food products. The designed sensors were based on a glassy carbon electrode as the substrate material and high molecular weight polyvinyl chloride (PVC) polymeric ion-sensing membranes doped with multiwalled carbon nanotubes (MWCNTs) to improve the potential stability and minimize signal drift. For determination of OXY, the sensing membrane was modified with potassium tetrakis (4-chlorophenyl) borate (K-TCPB), which was employed as a cation exchanger, and 2-hydroxypropyl-β-cyclodextrin (HP-ßCD), which was used as an ionophore. A linear response within a concentration range of 1 × 10− 6-1 × 10− 2 M with a slope of 59.47 mV/decade over a pH range of 1–5 was recorded. For the first time, two potentiometric electrodes were developed for determination of FLU, where the sensing membrane was modified with tetra dodecyl ammonium chloride (TDDAC) as an anion exchanger. A linear response within a concentration range of 1 × 10− 5-1 × 10− 2 M and a slope of -58.21 mV/decade over a pH range of 6–11 was observed. The suggested sensors were utilized for the selective determination of each drug in pure powder form, in veterinary formulations, and in spiked milk samples, with mean recoveries ranging from 98.50 to 102.10, and without any observed interference. The results acquired by the proposed sensors were statistically analyzed and compared with those acquired by the official methods, and the results showed no significant difference.Graphical

Photomorphogenesis of Myxococcus macrosporus: new insights for light-regulation of cell development

AbstractMyxobacteria are non-photosynthetic bacteria distinguished among prokaryotes by a multicellular stage in their life cycle known as fruiting bodies that are formed in response to nutrient deprivation and stimulated by light. Here, we report an entrained, rhythmic pattern of Myxococcus macrosporus fruiting bodies, forming consistently spaced concentric rings when grown in the dark. Light exposure disrupts this rhythmic phenotype, resulting in a sporadic arrangement and reduced fruiting-body count. M. macrosporus genome encodes a red-light photoreceptor, a bacteriophytochrome (BphP), previously shown to affect the fruiting-body formation in the related myxobacterium Stigmatella aurantiaca. Similarly, the formation of M. macrosporus fruiting bodies is also impacted by the exposure to BphP—specific wavelengths of light. RNA-Seq analysis of M. macrosporus revealed constitutive expression of the bphP gene. Phytochromes, as light-regulated enzymes, control many aspects of plant development including photomorphogenesis. They are intrinsically correlated to circadian clock proteins, impacting the overall light-mediated entrainment of the circadian clock. However, this functional relationship remains unexplored in non-photosynthetic prokaryotes. Genomic analysis unveiled the presence of multiple homologs of cyanobacterial core oscillatory gene, kaiC, in various myxobacteria, including M. macrosporus, S. aurantiaca and M. xanthus. RNA-Seq analysis verified the expression of all kaiC homologs in M. macrosporus and the closely related M. xanthus, which lacks bphP genes. Overall, this study unravels the rhythmic growth pattern during M. macrosporus development, governed by environmental factors such as light and nutrients. In addition, myxobacteria may have a time-measuring mechanism resembling the cyanobacterial circadian clock that links the photoreceptor (BphP) function to the observed rhythmic behavior. Graphical abstract

Hormetic responses to cadmium exposure in wheat seedlings: insights into morphological, physiological, and biochemical adaptations.

Cadmium is commonly recognized as toxic to plant growth, low-level Cd has promoting effects on growth performance, which is so-called hormesis. Although Cd toxicity in wheat has been widely investigated, knowledge of growth response to a broad range of Cd concentrations, especially extremely low concentrations, is still unknown. In this study, the morphological, physiological, and biochemical performance of wheat seedlings to a wide range of Cd concentrations (0-100 µΜ) were explored. Low Cd treatment (0.1-0.5µM) improved wheat biomass and root development by enhancing the photosynthetic system and antioxidant system ability. Photosynthetic rate (Pn) was improved by 5.72% under lower Cd treatment (1 µΜ), but inhibited by 6.05-49.85% from 5 to 100 µΜ. Excessive Cd accumulation induced oxidative injury manifesting higher MDA content, resulting in lower photosynthetic efficiency, stunted growth, and reduction of biomass. Further, the contents of ascorbate, glutathione, non-protein thiols, and phytochelatins were improved under 5-100 µΜ Cd treatment. The ascorbate peroxidase activity in the leaf showed a hormetic dose-response characteristic. Correlation analysis and partial least squares (PLS) results indicated that antioxidant enzymes and metabolites were closely correlated with Cd tolerance and accumulation. The results of the element network, correlation analysis, and PLS showed a crucial role for exogenous Cd levels in K, Fe, Cu, and Mn uptake and accumulation. These results provided a deeper understanding of the hormetic effect of Cd in wheat, which would be beneficial for improving the quality of hazard and risk assessments.

Flexible, Electrochemical Skin-Like Platform for Inflammatory Biomarker Monitoring.

Addressing global challenges in wound management has greatly encouraged the emergence of home diagnosis and monitoring devices. This technological shift has accelerated the development of new skin patch sensors for continuous health monitoring. A key requirement is the creation of flexible platforms capable of mimicking human skin features. Here, for the first time, an innovative, highly adaptable electrochemical biosensor with molecularly imprinted polymers (MIPs) is customized for the detection of the inflammatory biomarker interleukin-6 (IL-6). The 3-electrode gold pattern is geometrically standardized onto a 6µm thick polyimide flexible membrane, an optically transparent, and biocompatible polymeric substrate. Subsequently, a biomimetic sensing layer specifically designed for the detection of IL-6 target is produced on these transducers. The obtained MIP biosensor shows a good linear response within the concentration range 50pgmL-1-50ngmL-1, with a low limit of detection (8pgmL-1). X-ray photoelectron spectroscopy, scanning electron microscopy, and Fourier transform infrared spectroscopy characterizations confirm the modifications of the flexible gold transducer. After optimization, the biosensing device shows remarkable potential in terms of sensitivity, selectivity, and reproducibility. Overall, the integration of a low-cost electrochemical sensor on biocompatible flexible polymers opens the way for a new generation of monitoring tools with higher accuracy, less invasiveness, and greater patient comfort.

Gamma-aminobutyric acid elicits H2O2 signalling and promotes wheat seed germination under combined salt and heat stress

Background In the realm of wheat seed germination, abiotic stresses such as salinity and high temperature have been shown to hinder the process. These stresses can lead to the production of reactive oxygen species, which, within a certain concentration range, may actually facilitate seed germination. γ-aminobutyric acid (GABA), a non-protein amino acid, serves as a crucial signaling molecule in the promotion of seed germination. Nevertheless, the potential of GABA to regulate seed germination under the simultaneous stress of heat and salinity remains unexplored in current literature. Methods This study employed observational methods to assess seed germination rate (GR), physiological methods to measure H2O2 content, and the activities of glutamate decarboxylase (GAD), NADPH oxidase (NOX), superoxide dismutase (SOD), and catalase (CAT). The levels of ABA and GABA were quantified using high-performance liquid chromatography technology. Furthermore, quantitative real-time PCR technology was utilized to analyze the expression levels of two genes encoding antioxidant enzymes, MnSOD and CAT. Results The findings indicated that combined stress (30 °C + 50 mM NaCl) decreased the GR of wheat seeds to about 21%, while treatment with 2 mM GABA increased the GR to about 48%. However, the stimulatory effect of GABA was mitigated by the presence of ABA, dimethylthiourea, and NOX inhibitor, but was strengthened by H2O2, antioxidant enzyme inhibitor, fluridone, and gibberellin. In comparison to the control group (20 °C + 0 mM NaCl), this combined stress led to elevated levels of ABA, reduced GAD and NOX activity, and a decrease in H2O2 and GABA content. Further investigation revealed that this combined stress significantly suppressed the activity of superoxide dismutase (SOD) and catalase (CAT), as well as downregulated the gene expression levels of MnSOD and CAT. However, the study demonstrates that exogenous GABA effectively reversed the inhibitory effects of combined stress on wheat seed germination. These findings suggest that GABA-induced NOX-mediated H2O2 signalling plays a crucial role in mitigating the adverse impact of combined stress on wheat seed germination. This research holds significant theoretical and practical implications for the regulation of crop seed germination by GABA under conditions of combined stress.

Assessment of Adipocyte Transduction Using Different AAV Capsid Variants

Background/Objectives: Adeno-associated viruses (AAVs) are widely used as viral vectors for gene delivery in mammalian cells. We focused on the efficacy of the transduction of AAV2/5, 2/6, 2/8 and 2/9 expressing GFP in preadipocyte cells by live imaging microscopy using IncuCyte S3 and flow cytometry. Methods: Three transduction modes in 3T3-L1 preadipocyte cells assessed: AAV transduction in 3T3-L1 preadipocyte cells, transduction with further differentiation into mature adipocyte-like cells and the transduction of differentiated 3T3-L1 adipocytes. For the in vivo study, we injected AAV2/6, AAV2/8 and AAV2/9 in adipose tissue of C57BL6 mice, and the transduction capacity of AAV2/6, along with AAV2/8 and AAV2/9 was evaluated. Results: AAV2/6 demonstrated the highest transduction efficiency in 3T3-L1 preadipocytes, as it was 1.5–2-fold more effective than AAV2/5, and AAV2/8 in the range of viral concentrations from 2 × 104 to 1.6 × 105 VG/cell. AAV2/5 and AAV2/8 showed transduction efficiencies similar to each other. The expression of GFP under the CMV promoter remained stable for up to 20 days. The induction of 3T3-L1 differentiation in three days after AAV transduction did not alter the GFP expression level, and AAV2/6 showed the best transduction efficiency. AAV2/6 demonstrated the ability to transduce mature adipocytes. These results were confirmed by in vivo studies on C57BL6 mice. AAV2/6 had the highest transducing activity on both inguinal and interscapular adipose tissue. Conclusions: Thus, AAV2/6 has demonstrated higher transduction efficacy compared to AAV2/5, AAV2/8 and AAV2/9 both in 3T3-L1 adipocytes and adipose tissue in vivo, which proves its usability along with AAV2/8 and AAV2/9 for gene delivery to adipocytes.

Particle Properties and Flotation Characteristics of Difficult-to-Float Lean Coal

The flotation effect of lean coal is crucial for its clean utilization. Therefore, the flotation characteristics of difficult-to-float lean coal were studied. The analysis results of the feed properties showed that the ash content of the feed was high and the particle size was very fine. The minerals in the gangue mainly included sericite, kaolinite, quartz, white mica, and other substances. After flotation, the functional groups of the coal particles in the tailings decreased, and the absorption peak intensity weakened. Furthermore, the results of multi-factor flotation experiments showed that the dosages of the collector and the frother were significant factors affecting the yield of clean coal. The clean coal yield gradually increased with an increase in the two factors. The ash content of the clean coal increased with an increase in the frother dosage. Within the range of feed concentrations used in this work, the feed concentration was not a significant factor affecting the clean coal’s yield and ash content. Prediction models for the clean coal yield and ash content were proposed. Under optimized experimental conditions, the clean coal yield and the flotation perfection index were 72.15% and 46.63%, respectively, indicating a good flotation effect.

Exopolysaccharide (EPS) Produced by Leuconostoc mesenteroides SJC113: Characterization of Functional and Technological Properties and Application in Fat-Free Cheese

A Leuconostoc mesenteroides strain (SJC113) isolated from cheese curd was found to produce large amounts of a mucoid exopolysaccharide (EPS). An analysis revealed the glucan nature of the EPS with 84.5% (1→6)-linked α-d-glucose units and 5.6% (1,3→6)-linked α-d-glucose units as branching points. The EPS showed 52% dextranase resistance and a yield of 7.4 ± 0.9 g/L from MRS medium supplemented with 10% sucrose within 48 h. Ln. mesenteroides SJC113 was also characterized and tested for the production of EPS as a fat substitute in fresh cheese. Strain SJC113 showed high tolerance to a wide range of NaCl concentrations (2, 5 and 10%), high β-galactosidase activity (2368 ± 24 Miller units), cholesterol-reducing ability (14.8 ± 4.1%), free radical scavenging activity (11.7 ± 0.7%) and hydroxyl scavenging activity (15.7 ± 0.4%). The strain had no virulence genes and was sensitive to clinically important antibiotics such as ampicillin, tetracycline and chloramphenicol. Ln. mesenteroides SJC113 produced highly viscous EPS during storage at 8 °C in skim milk with 5% sucrose. Therefore, these conditions were used for EPS production in skim milk before incorporation into fresh cheese. Four types of fresh cheese were produced: full-fat cheese (FF) made from pasteurized whole milk, non-fat cheese (NF) made from pasteurized skim milk, non-fat cheese made from skim milk fermented with Ln. mesenteroides without added sugar (NFLn0) and non-fat cheese made from skim milk fermented with Ln. mesenteroides with 5% sucrose (NFLn5). While the NF cheeses had the highest viscosity and hardness, the NFLn5 cheeses showed lower firmness and viscosity, higher water-holding capacity and lower weight loss during storage. Overall, the NFLn5 cheeses had similar rheological properties to full-fat cheeses with a low degree of syneresis. It was thus shown that the glucan-type EPS produced by Ln. mesenteroides SJC113 can successfully replace fat without altering the texture of fresh cheese.

Trifolium repens extracts as a green corrosion inhibitor for carbon steel in a 3.5% NaCl solution

BackgroundMaterial degradation is a major issue that has been the subject of intense research and investigation by the scientific community. It has harmful consequences that require serious and careful intervention. However, restrictions on the use of inhibitors containing toxic compounds pose a significant challenge to the implementation of effective corrosion treatments. This has necessitated a continuous search for new and innovative ways to protect against material damage. Plant-derived natural inhibitors offer several advantages, including potent inhibitory effects, lack of toxicity, biodegradability, and environmentally sustainable origins. The purpose of this research was to evaluate the corrosion resistance of API5LX60 carbon steel in a 3.5 % NaCl environment using Trifolium repens as an environmentally friendly inhibitor. MethodsThe inhibitor extract was analysed using Fourier Transform Infrared (FTIR) spectroscopy. However, gravimetry and electrochemical methods (potentiodynamic polarization and electrochemical impedance spectroscopy (EIS)) were used to investigate the corrosion behaviour. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) were used to examine the surface morphology. Significant findingsAfter testing a range of concentrations in a 3.5 % NaCl medium, the highest level of inhibition (98 %) was obtained at 20 ppm, confirming the mixed action of the inhibitor with predominantly cathodic action. The inhibition mechanism involved physical adsorption on metal surfaces according to the Langmuir model, which enhances the corrosion-inhibiting ability; the extract forms a protective layer that successfully inhibits corrosion, as confirmed through electrochemical and surface analysis. These results demonstrate that the extract acts as a potent anticorrosive agent.

Portable Electrochemical Immunosensor Based on a Gold Microblobs-Optimized Screen-Printed Electrode for SARS-CoV-2 Diagnosis

The development of biosensors for determining the most diverse biomolecules is a constant focus of many research groups. There is a latent need to propose sensors that combine portability, simple measurements, and good analytical performance. Here, we propose an electrochemical immunosensor that is fully portable and energy-independent for diagnosing antibodies against SARS-CoV-2 (the virus that causes COVID-19). Initially, disposable screen-printed carbon electrodes (SPEs) were covered by gold microblobs (AuMBs), which were synthesized amperometrically from Au3+ ions. Then, the SPE-AuMBs were coated with cysteamine, which allowed the N-hydroxysuccinimide-activated SARS-CoV-2 antigen (spike protein) to be immobilized. The antigen-activated electrode was used to detect COVID-19 antibodies from current measurements obtained by differential pulse voltammetry. The AuMBs synthesis time was optimized, and the presence of gold structures improved the electrochemical responses of the SPE. It was possible to quantitatively determine antibodies in the concentration range of 0.25 to 10 µg mL−1. This range includes concentrations found in biological fluids from patients at any stage of the disease. An analysis took approximately the same time as traditional rapid nasal tests (20 min) and costed less, considering all the steps necessary to prepare a disposable antigen-functionalized SPE.

Dissipation and Dietary Risk Assessment of the Fungicide Pyraclostrobin in Apples Using Ultra-High Performance Liquid Chromatography–Mass Spectrometry

The fungicide pyraclostrobin is the main measure used to control apple alternaria blotch in production. To evaluate the potential dietary risks for consumers, the dissipation and terminal residues of pyraclostrobin were investigated using ultra-high performance liquid chromatography–mass spectrometry (UHPLC–MS/MS). Pyraclostrobin in apples was extracted by acetonitrile with 2% ammonia and then purified using primary secondary amine (PSA) and graphitized carbon black (GCB). The method showed good linearity within the concentration range of 0.005–0.1 mg L−1, with a coefficient of determination (R2) ≥ 0.9958. The recoveries ranged from 96.0% to 103.8%, with relative standard deviations (RSDs) between 0.8% and 2.3%. The limit of quantification (LOQ) was 0.01 mg kg−1. Pyraclostrobin dispersible oil suspension was applied in 12 apple fields across China according to good agricultural practices (GAPs). In Beijing and Shandong, the dissipation of pyraclostrobin followed first-order kinetic equations, with a half-life of 11 days. The terminal residues ranged from <0.01 to 0.09 mg kg−1. The national estimated daily intake (NEDI) of pyraclostrobin was compared with the acceptable daily intake (ADI), resulting in risk quotient (RQc) of 80.8%. These results suggest that pyraclostrobin poses a low health risk to consumers under GAP conditions and according to recommended dosages.

Development and Validation of an LC-MS/MS Assay for the Quantitation of MO-OH-Nap Tropolone in Mouse Plasma: Application to In Vitro and In Vivo Pharmacokinetic Studies

A rapid, selective, and sensitive liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) method was developed and validated for the quantitation of MO-OH-Nap tropolone (MO-OH-Nap) in mouse plasma. MO-OH-Nap is an α-substituted tropolone with anti-proliferative properties in various cancer cell lines. Detection and separation of analytes was achieved on an ACE Excel C18 (1.7 µm, 100 × 2.1 mm, MAC-MOD Analytical, Chadds Ford, PA, USA) column with mobile phase consisting of 0.05% trifluoroacetic acid in water (mobile phase A) and 0.05% trifluoroacetic acid in acetonitrile (mobile phase B), with an isocratic elution of 15:85% (A:B) at a total flow rate of 0.25 mL/min. The LC-MS/MS system was operated at unit resolution in multiple reaction monitoring (MRM) mode, using precursor ion > product ion combination of 249.10 > 202.15 m/z for MO-OH-Nap and 305.10 > 215.05 m/z for the internal standard (IS), BA-SM-OM. The MS/MS response was linear over a concentration range of 1 to 500 ng/mL with a correlation coefficient (r2) of ≥0.987. The within- and between-batch precision (%RSD) and accuracy (%Bias) were within acceptable limits. The validated method was successfully applied to determine MO-OH-Nap metabolic stability, plasma protein binding, and bio-distribution studies of MO-OH-Nap in CD-1 mice.

Flame retardant, hexabromocyclododecane, increases production of pro-inflammatory cytokines, interleukin 1-beta and interleukin 6, in human immune cells.

Hexabromocyclododecane (HBCD) is an environmental contaminant due to its use as a flame retardant in a variety of applications ranging from building insulation, furniture upholstery, and housing for appliances and electronics. HBCD is found in wildlife, human breastmilk, and serum. Interleukin 1-beta (IL-1β) and interleukin 6 (IL-6) are pro-inflammatory cytokines, whose dysregulation is associated with chronic inflammation and the pathologies that result, such as tumor growth, rheumatoid arthritis, Crohn's disease, and multiple sclerosis. HBCD has been shown to increase the secretion of both IL-1β and IL-6 from human immune cells. However, it is not clear if these increases are due solely to HBCD effects on the secretory process or whether it is stimulating cellular production of IL-1β and IL-6. This study examines if HBCD can increase the production of IL-1β and IL-6 by immune cells by simultaneously assessing secreted levels and cellular levels of these cytokines. Additionally, the mechanisms for any observed changes in production are investigated. Peripheral blood mononuclear cells were exposed to HBCD over a range of concentrations and lengths of exposure. HBCD was found to stimulate IL-1β and IL-6 production after 6hrs. of exposure and production was sustained and intensified at 24 hrs. This increase in IL-1β and IL-6 production appears to, in part, be a result of increased mRNA expression. Additionally, the MAPK pathways, specifically the p38 and p44/42 pathways, appear to be required for HBCD-induced increases in IL-1β and IL-6 production.