Concentration Range Research Articles

МЕТОДОЛОГИЧЕСКИЕ ОСНОВЫ МАТЕРИАЛОВЕДЧЕСКОЙ ОЦЕНКИ КАЧЕСТВА СМАЗОЧНЫХ СРЕД ДЛЯ НАГРУЖЕННЫХ СОПРЯЖЕНИЙ МАШИН И МЕХАНИЗМОВ. Сообщение 2. Влияние состава смазочных сред на структурно-фазовое состояние зоны деформации металлических трибосопряжений и их антифрикционные свойства

The results of experimental studies of deformation and diffusion in the surface layers of metallic frictional couples, which form the experimental and theoretical basis of the materials science approach to the quality evaluation of lubricants, are presented. The concepts of the component’s role for the lubricating medium in the implementation of the plasticizing and strengthening triboeffect are formulated. Structural condition characteristics for the surface layers of copper alloys during friction on steel in the mode of boundary lubrication in surface-active lubricants, are described. The conditions for achieving minimum power losses of such tribosystems for friction and wear have been found. The greatest service life of tribounit in a lubricating medium containing surfactants is resulted from wear resistance increase of a copper alloy with a relative decrease in hardness and increased plasticity of its surface layer. At the same time, a decrease in hardness due to the plasticizing effect of surfactants occurs only in the near-surface deformed layer of tribomaterial, while in its deeper layers with no plasticization resulted from a lubricating medium effect, the mechanical characteristics of the antifriction alloy remain at the required high level. It is demonstrated that alloys with a single-phase structure of an α-solid solution and a wide concentration range of solubility of the alloying element in the solid state meet these requirements. It is found that such boundary conditions are provided by the presence of stationary macroscopic diffusion flows of alloying elements in the zone of contact deformation of a polycomponent tribomaterial. The role of local diffusion phenomena in quasispinodal phase transitions is indicated. Examples of the selective transfer phenomenon during friction in industrial lubricants, are given.

Intramolecular feedback regulation of the LRRK2 Roc G domain by a LRRK2 kinase-dependent mechanism.

The Parkinson's disease (PD)-linked protein Leucine-Rich Repeat Kinase 2 (LRRK2) consists of seven domains, including a kinase and a Roc G domain. Despite the availability of several high-resolution structures, the dynamic regulation of its unique intramolecular domain stack is nevertheless still not well understood. By in-depth biochemical analysis, assessing the Michaelis-Menten kinetics of the Roc G domain, we have confirmed that LRRK2 has, similar to other Roco protein family members, a KM value of LRRK2 that lies within the range of the physiological GTP concentrations within the cell. Furthermore, the R1441G PD variant located within a mutational hotspot in the Roc domain showed an increased catalytic efficiency. In contrast, the most common PD variant G2019S, located in the kinase domain, showed an increased KM and reduced catalytic efficiency, suggesting a negative feedback mechanism from the kinase domain to the G domain. Autophosphorylation of the G1+2 residue (T1343) in the Roc P-loop motif is critical for this phosphoregulation of both the KM and the kcat values of the Roc-catalyzed GTP hydrolysis, most likely by changing the monomer-dimer equilibrium. The LRRK2 T1343A variant has a similar increased kinase activity in cells compared to G2019S and the double mutant T1343A/G2019S has no further increased activity, suggesting that T1343 is crucial for the negative feedback in the LRRK2 signaling cascade. Together, our data reveal a novel intramolecular feedback regulation of the LRRK2 Roc G domain by a LRRK2 kinase-dependent mechanism. Interestingly, PD mutants differently change the kinetics of the GTPase cycle, which might in part explain the difference in penetrance of these mutations in PD patients.

Toxicity Assessment of Four Commonly Used Insecticides to the Corn-Infesting Rice Weevil (Coleoptera: Curculionidae)1

Abstract Rice weevil, Sitophilus oryzae (L.) (Coleoptera: Curculionidae), is one of the most significant pests of corn (Zea mays L.) and other stored grains. Historically, synthetic insecticides have been widely used to control pest populations due to their effectiveness, convenience of storage and application, and persistent activity. This study aimed to assess the toxicity profiles of four commonly used insecticides, including pirimiphos-methyl, deltamethrin, deltamethrin plus (S)-methoprene, and malathion, to rice weevil adults. The weevils were exposed to a range of concentrations of each insecticide to generate concentration–mortality response curves and median lethal concentrations (LC50) of each insecticide. Pirimiphos-methyl exhibited the highest toxicity to the adult weevils, with an LC50 of 0.74 ppm (95% confidence limit [CL], 0.57–0.92). Based on nonoverlapping 95% CLs, we determined that the LC50 of pirimiphos-methyl was significantly lower than the LC50 of malathion (7.08 ppm [95% CL, 5.44–9.01]), deltamethrin (9.11 ppm [95% CL, 6.89–12.6]), and deltamethrin plus (S)-methoprene (13.94 ppm [95% CL, 9.71–18.60]). Thus, the relative toxicity of these four insecticides to adult rice weevils was pirimiphos-methyl > malathion > deltamethrin > deltamethrin plus (S)-methoprene. We subsequently compared the LC50 value of each insecticide with that of the label-recommended application rate and found that only malathion aligned with the recommended label rate. These findings could prove useful in refining application rates for the effective control of rice weevils infesting stored grains.

Method for determination of cytisine in post-mortem biological matrices and its application to two forensic cases.

Cytisine is the active ingredient in preparations used for smoking cessation. Its popularity is attributed to its low cost, efficacy, and low incidence of adverse effects. Additionally, its easy over-the-counter availability is also significant. This accessibility makes it a potential substance for use in suicidal attempts. The aim of this study was to develop a method for the determination of cytisine in biological material for use in clinical and forensic toxicology, and to apply this method in authentic cases. Biological samples were subjected to liquid-liquid extraction using cytisine-d4 as an internal standard. Analyses were performed using a Hydrophilic Interaction Liquid Chromatography (HILIC) column with the technique of ultra-high-performance liquid chromatography coupled with triple quadrupole tandem mass spectrometry. For both matrices (blood and urine), the linear concentration range was 5-1000ng/mL. The method met all validation requirements. The concentration of cytisine in a man taking it for smoking cessation in post-mortem materials was 21.4ng/mL in blood, 958.9ng/mL in urine, ca. 30ng/mL in vitreous humor, and ca. 40ng/mL in bile. In contrast, for a man with cytisine intoxication, the concentration was 174.6ng/mL in blood and > 10,000ng/mL in urine. In both cases, no N-methylcytisine was detected. The developed method can be used for the determination of cytisine in post-mortem biological matrices as well as for clinical purpose. We presented the concentrations of cytisine in the post-mortem biological samples of a man taking cytisine for smoking cessation and of a man with suicidal cytisine poisoning.

A Selective Electrochemical Sensor for Bisphenol A Detection Based on Cadmium (II) (bromophenyl)porphyrin and Gold Nanoparticles

Bisphenol A (BPA) is a commonly synthetic chemical mainly used in producing plastic items. It is an endocrine-disrupting compound that causes irreversible health and environmental damage. Developing a simple method for BPA effective quantitative monitoring is emergently necessary. Herein, a novel electrochemical sensor for BPA detection based on [(5,10,15,20-tetrakis(p-bromophenyl) porphyrinato] cadmium (II) [(CdTBrPP)] and gold nanoparticle (AuNPs)-modified screen-printed carbon electrode (SPCE) was elaborated. CdTBrPP was synthesized and then characterized with Ultraviolet–Visible Spectroscopy (UV/vis), Infrared Spectroscopy (IR), and Proton Nuclear Magnetic Resonance Spectroscopy (1H NMR) to confirm its successful synthesis. After drop-coating AuNPs and CdTBrPP on the SPCE, the sensor performance was evaluated using square wave voltammetry (SWV), a linear response in a concentration range from 10−11 M to 10−2 M, with a low detection limit (LOD) of 9.5 pM. The CdTBrPP/AuNPs/SPCE sensor demonstrates a high selectivity and reproducibility, making it a promising candidate for developing a low-cost water-monitoring system for detecting BPA. Additionally, the proposed sensor effectively detected BPA in both tap and mineral water samples.

Genetically Encoded Biosensor HyPer as a Tool for Quantification of Intracellular Hydrogen Peroxide Concentrations

This mini-reviewsystematizes information on methods for quantitative assessment of intracellular hydrogenperoxide concentration based on the use of a genetically encodedperoxide sensor HyPer. Two approaches are being considered: 1) calibrationof the biosensor using exogenous hydrogen peroxide, based on assessingthe rate of peroxide penetration into cells and intracellular peroxidaseactivity; 2) direct determination of the intracellular peroxide content, basedon measuring the level of oxidation of the biosensor, theoxidation reaction constant and the reduction reaction constant of HyPerin the cells. The use of these methods makes itpossible to solve a wide range of tasks in cellularredox biology—to determine the range of physiological anddamaging concentrations of hydrogen peroxide in cells, to evaluate theeffectiveness of the antioxidant defense system in various cellular compartmentsunder conditions of oxidative stress, to determine the contribution ofvarious enzymatic systems to the peroxidase activity of cells, andto characterize antioxidant defense systems in various biological contexts (inthe process of cellular senescence, differentiation, reprogramming, during the developmentof pathologies). The described methods can be adapted for othergenetically encoded hydrogen peroxide biosensors.

Enhanced Electrochemical Detection of Orthophosphate in Potable Water Using Zinc-Cobalt Oxide Nanocomposite-Modified Nickel Foam Electrodes

Abstract This study presents a novel approach to electrochemical detection of orthophosphate in potable water using hydrothermally synthesized nickel foam electrodes, modified with cobalt oxide (CoOx), zinc oxide (ZnOx), and zinc-cobalt oxide (ZnCoOx) nanocomposites. The incorporation of zinc-cobalt oxide into the electrode significantly enhances its stability and detection capability. In-situ phosphate detection was performed using voltammetric techniques in a highly alkaline environment (pH 14) facilitated by sodium hydroxide (NaOH). Comprehensive electrode characterization, including cyclic voltammetry (0 to 0.6 V at a scan rate of 50 mV/s), electrochemical impedance spectroscopy (105 to 10-2 Hz), scanning electron microscopy, and energy-dispersive X-ray spectroscopy, confirmed the superior performance of the synthesized electrodes. Among the tested configurations, the zinc-cobalt oxide nanocomposite on nickel foam exhibited outstanding sensitivity, with a sensitivity of 0.4 μA/μM across a concentration range of 0 to 40 μM, and an elevated sensitivity of 4.26 μA/μM within the 50 to 100 μM range. The electrode achieved a remarkably low detection limit of 0.171 μM/L (0 to 40 μM detection range) and 0.324 μM/L (50 to 100 μM, detection range), underscoring its potential for highly accurate phosphate detection. These findings highlight the sensor's applicability for diverse practical uses in water quality monitoring.

Ultrafine Particle Generation from Ozone Oxidation of Cannabis Smoke.

Cannabis smoke is a complex aerosol mixture, featuring characteristic monoterpenes and sesquiterpenes which are susceptible to reaction with ozone and other oxidants. These reactions form less-volatile species which can contribute to secondary organic aerosol (SOA) and ultrafine particle (UFP) formation. In this work, the reaction of ozone with cannabis smoke was observed in an environmental chamber. Particle size distribution, and gas-phase and particle-phase composition were monitored in real time. The diameter of primary particles ranged from 10-1 to 1 μm. Ultrafine particle formation occurred when cannabis smoke was exposed to ozone levels greater than 10 ppb, over the entire observed primary particle concentration range (1030-4580 μg m-3). Gas-phase measurements indicate that monoterpene and sesquiterpene levels decayed rapidly upon ozone exposure, while oxygen-containing species were formed during oxidation. On the other hand, measurements of particle composition showed an increase in nitrogen-containing species during oxidation. Although ozone was the only oxidant added to cannabis smoke in the chamber, it is believed that the OH radical plays an important role in the oxidation mechanism, where OH results from the reaction of ozone with terpenes and sesquiterpenes. Overall, smoking cannabis in ozone-rich environments, both indoors and outdoors, will likely lead to UFP formation.

HYDRAULIC DYNAMICS OF THE REGOLITHIC NEOSOL IN THE CERRADO OF THE SERRA DA CANASTRA NATIONAL PARK-MG

The knowledge of soil water dynamics, as elements are added, removed, and transformed, is an aid to understanding the processes at play in landscapes. Understanding the functioning of natural environments not only contributes to comprehending the natural dynamics of systems but also serves as a reference for adopting measures in areas at different stages of degradation. In this sense, this study sought to analyze the physical/hydraulic characteristics of the Regolithic Neosol in the Serra da Canastra National Park, MG. For this purpose, two different models of field infiltrators were used: namely a rain simulator and a concentric ring infiltrometer. Results involving the use of a rain simulator indicated high soil infiltration capacity (99.31%) even when subjected to high-intensity events (57.4 mm/h). The ring infiltrometer revealed high values of basic infiltration velocity (317.58 mm/h). These values indicate that despite being shallow (20 cm), the soil, characterized by coarse material (sand and lateritic gravel), has a high capacity to incorporate water precipitated into the profile, generating subsurface lateral flows between the higher and lower parts of the slope and causing the movement of iron along with underground water flow.

The range and variation in serum estradiol concentration in perimenopausal and postmenopausal women treated with transdermal estradiol in a real-world setting: a cross-sectional study.

The aims of the study are to explore the range and variation in serum estradiol concentration, and to estimate the prevalence of "poor absorption" (women using licensed estradiol doses with subtherapeutic levels), in perimenopausal and postmenopausal women using transdermal estradiol in the real world. This is a cross-sectional analysis in a specialist menopause clinic in the UK. Serum samples were obtained from 1,508 perimenopausal and postmenopausal women. A total of 61.87% were using licensed doses. The median estradiol concentration was 355.26 pmol/L (interquartile range 198.44-646.15 pmol/L). A reference interval for the whole cohort was defined as 54.62-2,050.55 pmol/L. There was substantial interindividual variation across the dose range. Variance was greater in younger women (P = 0.002) and gel users (P = 0.002). There was a trend toward greater variance in women using higher doses, but the association failed to reach statistical significance (P = 0.074). One in four women (24.84%) using the highest licensed dose had subtherapeutic levels (<200 pmol/L). Older women (≥50 y) and patch users were more likely to have low levels (odds ratio 1.77, 95% confidence interval 1.22-2.62, P = 0.003; and odds ratio 1.51, 95% confidence interval 1.18-1.95, P = 0.001, respectively). The reference interval for perimenopausal and postmenopausal women using on-label and off-label doses of transdermal estradiol in the real world is wide, and there is considerable interindividual variation. The number of estradiol users with low estradiol levels (<200 pmol/L) is higher than previously recognized. Measurement of serum estradiol can be helpful to identify women who may benefit from an off-label dose. Dose customization is key to ensure that all women can reap the benefits of HT.

Concentric‐Ring Patterns of Higher‐Order Lumps in the Kadomtsev–Petviashvili I Equation

ABSTRACTLarge‐time patterns of general higher‐order lump solutions in the Kadomtsev–Petviashvili I (KP‐I) equation are investigated. It is shown that when the index vector of the general lump solution is a sequence of consecutive odd integers starting from one, the large‐time pattern in the spatial ‐plane generically would comprise fundamental lumps uniformly distributed on concentric rings. For other index vectors, the large‐time pattern would comprise fundamental lumps in the outer region as described analytically by the nonzero‐root structure of the associated Wronskian–Hermite polynomial, together with possible fundamental lumps in the inner region that are uniformly distributed on concentric rings generically. Leading‐order predictions of fundamental lumps in these solution patterns are also derived. The predicted patterns at large times are compared to true solutions, and good agreement is observed.

Effect of Adaptation to High Concentrations of Cadmium on Soil Phytoremediation Potential of the Middle European Ecotype of a Cosmopolitan Cadmium Hyperaccumulator Solanum nigrum L.

The Cd hyperaccumulator Solanum nigrum L. exhibits a cosmopolitan character and proven high and differentiated efficiency. This suggests the possibility of optimizing its Cd phytoremediation capacity and applicability through searching among remote ecotypes/genotypes. However, the extensive studies on this hyperaccumulator have been limited to Far East (Asian) regions. Pioneer pot experiments on the Middle European ecotype of S. nigrum within a concentration range of 0–50 mg kg−1 Cd in soil revealed its Cd phytoremediation capacity to be comparable to Asian ecotypes but with a fundamentally different Cd tolerance threshold. While biomass of the Asian ecotypes declined sharply at Csoil ≈ 10 mg kg−1 Cd, in the Middle European ecotype, a gradual mild biomass decrease occurred within the whole Csoil ≈ 0–50 mg kg−1 Cd range with no toxic symptoms. Its adapted A50 variety was obtained from the seeds of first-generation plants grown in soil with Csoil ≈ 50 mg kg−1 Cd. In this variety, Cd tolerance, accumulation performance, and all physiological parameters (chlorophyll, carotenoids, RuBisCO, and first- and second-line defense anti-oxidant activity) were significantly enhanced, while cell damage by ROS was considerably lesser. This makes the Middle European ecotype and its adapted variety A50 particularly useful to sustainable decontamination of heavily polluted “hot spots” in degraded post-industrial areas.

Non-enzymatic Electrochemical Sensor Behaviors of Polyaniline: Silicene Nanocomposite- A Study on Sensitive and Selective Sensor Design against Glucose

Abstract This study represents a non-enzymatic electrochemical sensor based on a Polyaniline: Silicene nanocomposite for the detection of glucose. A simple, clean and a low-cost sonication technique was used to prepare silicene nanosheets. XRD, FFT, SAED, HRTEM and FT-IR tecniques were used for characterization and CV for the detection of glucose. Current-voltage measurements were taken at various scanning rates (10-100 mV/s). The active surface areas of PANI and PANI: Silicene nanocomposite based sensors were determined as 0.122 cm2 and 0.179 cm2, respectively. The nanocomposite material presented large peak currents, indicating that the nanocomposite elicited enhanced electrochemical activity with the presence of silicene for glucose detection in the concentration range of 0.75 – 12 mM. At a scan rate of 50 mV/s, PANI-based sensor exhibited a sensitivity of 6.51 μAmM−1 cm−2 with detection limit of 5.52 μM, while the PANI: Silicene nanocomposite-based sensor exhibited a sensitivity of 20.93 μAmM−1 cm−2 with 0.43 μM detection limit. The selectivity of the sensors to measure glucose was also explored by characterizing their electrochemical performances in the presence of fructose and lactose. Due to these enhanced electrochemical performance, PANI: Silicene nanocomposite could be a promising biosensor material for glucose analysis for biomedical applications.

Sensitive and Discriminative Fluorescent Detection of Volatile Primary Aliphatic Diamine Vapors from Monoamines

The discriminative detection of volatile primary aliphatic diamines (VPADs) is a relevant and timely issue. This paper explores the distinctive optical features of H-type and J-type aggregates on paper-based (PB) films, namely H-PB and J-PB films, respectively, of a Lewis acidic Zn(salen)-type complex upon chemisorption of vapors of ditopic VPADs versus those of monotopic volatile amines. While volatile monotopic Lewis bases upon chemisorption give rise to mono-adducts accompanied by enhancement of the fluorescence, in contrast, VPADs act as ditopic bases forming di-adducts with distinct optical properties, leading to fluorescence quenching. This behavior enables the sensitive and discriminative detection of VPAD vapors from those of volatile monoamines. For example, for ethylenediamine (EDA), using J-PB films, sensitive detection is achieved with a LOD down to 6.6 ppm, lower than the OSHA permissible exposure limit of 10 ppm for EDA, and a linear dynamic range up to 100 ppm. Instead, H-PB films enable the detection of EDA vapors at higher ppm concentrations (up to 3000 ppm) with a linearity of up to 1000 ppm. Thus, the combination of both H-PB and J-PB films of the Zn(salen)-type complex represents a unique example of the sensitive and discriminative detection of EDA vapors in such a wide concentration range.

Identification of Gene‐Therapy Responsive Blood Biomarkers in mdx Mouse Model

ABSTRACTIntroductionIdentifying serum biomarkers that reflect the restoration of dystrophin in skeletal muscle is important for evaluating the effect of dystrophin‐restoring therapies in preclinical and clinical trials. Many potential blood biomarkers have been identified in Duchenne muscular dystrophy (DMD) patients, which change with disease progression or respond to pharmacological treatment. In this study, it was suggested that a panel of such blood biomarker candidates could be used to monitor dystrophin rescue in mdx mice treated with microdystrophin based therapies.MethodsPlasma samples from mdx mice treated with the microdystrophin therapy SGT‐001 were analysed with an antibody suspension bead array consisting of 87 antibodies. The array targets 83 unique proteins previously identified as biomarker candidates for DMD. Each sample was assayed at two different plasma dilutions to cover a broader concentration range. Protein concentrations estimated as Median fluorescent intensities (MFI) were correlated to dystrophin expression in muscle tissue, as measured by immunohistochemistry and Western blot. Thirteen of the targets were selected and analysed in a DMD and Becker muscular dystrophy (BMD) longitudinal natural history cohort using a suspension bead array.ResultsTen proteins were found to be significantly elevated in untreated mdx mice compared with C57 wild‐type mice and to correlate with dystrophin expression (Spearman's correlation, FDR &lt; 0.05) upon gene transfer in mdx mice. Translatability of these biomarkers from animal models to patients was evaluated by exploring abundance trajectories over time in both DMD and BMD patients and association with dystrophin expression in BMD patients. Consistent with the observations in mouse, six of these biomarker candidates were more abundant in DMD patients compared with controls, and six were also differentially abundant between BMD and DMD patients. Among them, serum titin was shown to be associated with dystrophin expression in BMD patients, having a steeper decline over time in patients with low dystrophin expression in tibialis anterior compared with patients with high expression. Myosine light chain 3 had a steeper decline with time in DMD patients compared with BMD patients.ConclusionsThe 10 biomarker candidates identified in mouse plasma are related to muscle contraction, glycolysis, microtubule formation and protein degradation. Human titin and myosine light chain 3 were the most interesting candidates as explorative biomarkers to monitor microdystrophin expression in gene therapies. If confirmed, these biomarkers could be used to detect restoration of dystrophin expression per se, monitor changes in dystrophin expression over time and potentially confirm disease phenotype changes from severe to mild disease forms.

Long-term exposure to ambient air pollution and the incidence of systemic lupus erythematosus.

The relationship between air pollution and the risk of systemic lupus erythematosus (SLE) remains inconclusive. Here, we investigated the associations between long-term exposure to ambient air pollutants and incident SLE, based on a cohort of 502,004 participants free of SLE at baseline from UK Biobank. During a median of 13.65 follow-up years, 638 patients with SLE were identified. For each increase of interquartile range in air pollutant concentrations, the hazard ratios (HRs) and 95% confidence intervals (CIs) of SLE were 1.15 (1.04-1.27) for nitrogen dioxide (NO2), 1.08 (1.00-1.17) for nitrogen oxides (NOx), 1.13 (1.03-1.24) for particulate matter with the diameters ≤ 2.5 μm (PM2.5), 1.06 (0.99 -1.14) for particulate matter with diameter between 2.5 μm and 10 μm (PMcoarse), and 1.10 (1.02-1.18) for particulate matter with diameter ≤ 10 μm (PM10), respectively. A non-linear relationship of PMcoarse with SLE risk was detected by using restricted cubic spline models (Pnon-linearity=0.009), but not for the remaining air pollutants. Furthermore, smoking and long-term exposure to PM pollutants had significant additive interaction on SLE risk, with a relative excess risk of additive interaction (RERI) of 0.07 (95% CI: 0.02-0.09) for PM2.5, and 0.05 (95% CI: 0.01-0.08) for PM10. Additive interactions were also observed for genetic risk and PMcoarse (RERI: 0.04, 95% CI: 0.00-0.07) and PM10 (RERI: 0.04, 95% CI: 0.02-0.06) on SLE risk. In conclusion, our findings emphasize the significance of evaluating the impacts of long-term exposure to ambient air pollutants in preventing SLE, and highlight the necessity to identify individuals who smoke and have a high genetic risk to minimize the harmful effects of air pollution on the development of SLE.

Impact of Brake Wear Particles on Eukaryotic Cell Viability and Associated Oxidative Stress Responses

In this study, the cytotoxic effects of brake wear particles (≥250 nm ceramic/ceramic wear particles (CCWPs) and ≤100 nm ceramic/steel wear particles (CSWPs)) and 100 nm iron (III) oxide ultrafine particles (IOUFPs) on human lung carcinoma (A549) and Chinese hamster ovary (CHO) cells were investigated. Cell viability was determined using the MTT and Calcein AM methods. Oxidative stress was assessed by measuring reactive oxygen species (ROS), intracellular reduced glutathione (GSH), and malondialdehyde (MDA) concentrations under exposure to the above particles in the concentration range of 10–80 µg/mL. The initial assessments of CCWPs and CSWPs on the cell viability were performed after a 4-h exposure but later extended to 24 h to investigate the time-dependent of the cell viability and oxidative stress. MTT and Calcein AM assays indicated that the A549 cells are less susceptible to CCWPs and CSWPs than the CHO cells when exposed for both 4 h and 24 h. This study highlights that oxidative stress induced by CCWPs, CSWPs, and IOUFPs is cell-specific. While CCWPs did not affect glutathione (GSH) levels in the CHO cells, it significantly reduced GSH levels in A549 cells, with the exception of 80 µg/mL. Both CCWPs and CSWPs increased the lipid peroxidation in both cell types; however, the A549 cells demonstrated lower sensitivity to these treatments.

Sensitive Detection of Hg2+ and l-Cysteine through Optical Asymmetry-Tuned Fluorescence Switch Off-On Behavior in N-Doped Chiral Carbon Dot.

Blue-emissive nitrogen-doped chiral carbon dots (d-NCD230 and l-NCD230) exhibiting antipodal chiroptical activity, synthesized from the thermal pyrolysis of citric acid and d/l-aspartic acid in 1:2 molar ratios, have been explored as chirality-based fluorescent turn-off/on probes for the detection of Hg2+ and l-cysteine (l-Cys). Circular dichroism (CD) spectroscopy revealed that the chiroptical activity originates from a synergy among intrinsic chirality, chiral precursors on the NCD surface, and hybridization of lower energy levels within the embedded chiral chromophore. Quantitative analysis of optical asymmetry using the Kuhn asymmetry factor (g) at the CD signal of 312 nm showed a higher value for d-NCD230 (1.03 × 10-4) compared to l-NCD230 (1.13 × 10-5). Moreover, we have demonstrated chirality transfer and chiral inversion phenomena in d/l-NCDs by preparing carbon dots with different precursor ratios at different temperatures and probing them through CD spectroscopy. The NCDs exhibited selective fluorescence quenching in the presence of Hg2+, demonstrating linearity in the Stern-Volmer plot. Limits of detection (LODs) for Hg2+ were calculated to be 129 and 192 nM for d-NCD230 and l-NCD230, respectively, in the 0-150 μM concentration range. The quenching mechanism involves nonradiative electron transfer due to Hg2+ binding to oxygen-rich functional groups on the d/l-NCD230 surface. The slight variation in LOD values between d-NCD230 and l-NCD230 indicates the negligible effect of the chirality on Hg2+ sensing. Notably, the fluorescence intensity of d/l-NCD230 could be restored upon adding l-cysteine, with d-NCD230 showing a more pronounced enhancement than l-NCD230. This differential response is attributed to a preferential stereoselective interaction arising from the homochirality of d-NCD230/Hg2+ and l-cysteine. These findings demonstrate the potential of chiral nitrogen-doped carbon dots as sensitive and selective probes for Hg2+ and l-cysteine, with implications for environmental monitoring and biological sensing applications.

L-Cysteine/Silver Nitrate/Iodate Anions System: Peculiarities of Supramolecular Gel Formation with and Without Visible-Light Exposure

In this study, novel anion photo-responsive supramolecular hydrogels based on cysteine–silver sol (CSS) and iodate anions (IO3−) were prepared. The peculiarities of the self-assembly process of gel formation in the dark and under visible-light exposure were studied using a complex of modern physico-chemical methods of analysis, including viscosimetry, UV spectroscopy, dynamic light scattering, electrophoretic light scattering, scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray photoelectron spectroscopy. In the dark phase, the formation of weak snot-like gels takes place in a quite narrow IO3− ion concentration range. The visible-light exposure of these gels leads to an increase in their viscosity and dramatic change in their color. The morphology of gels alters after light irradiation that is reflected in the formation of a huge number of spherical/elliptical particles and the thickening of the fibers of the gel network. The interaction of CSS with IO3− anions has features of a redox process, which leads to the formation of silver iodide/silver oxide nanoparticles inside and on the surface of CSS particles. CSS possesses selectivity only to IO3− anions compared to many other inorganic ions relevant for humans and the environment. Thus, the CSS/IO3− system is non-trivial and can be considered as a novel low-molecular-weight gelator with photosensitive properties, as another way to produce silver iodide nanoparticles, and as a new approach for IO3− ion detection.

Use of two-dimensional correlation spectroscopy in chemical analysis

An overview of the main applications of generalized two-dimensional correlation spectroscopy (2D-COS) in analytical chemistry is presented. 2D-COS is a method used to analyze datasets obtained from spectroscopic measurements. This approach is based on the use of two-dimensional correlation maps to identify and analyze correlations between different regions of the spectrum or data from two measurement methods. The purpose of using 2D-COS is to increase the amount of analytical information by revealing hidden data correlations. Analyzing such correlations for series of spectral data obtained for a certain range of analyte concentrations, pH, or component ratios of a mixture, as well as changes in temperature or other external factors, allows researchers to investigate and identify chemical processes and interactions that cannot be directly obtained from the spectra. Compared to one-dimensional spectra, 2D-COS offers significant analytical information for complex mixtures, particularly in identifying components and determining composition. Additionally, 2D-COS can be used to monitor changes in a sample over time, making it a valuable tool for studying dynamically changing systems. Overall, 2D-COS is a highly versatile approach that can be used in conjunction with a large number of methods for most analytical tasks and complex objects, including those without sample preparation. The review presents advancements in the application of 2D-COS as of early September 2023.