Cysteine Research Articles

Evaluating the impact of redox potential on the growth capacity of anaerobic gut fungi

Abstract Anaerobic gut fungi (AGF, Neocallimastigomycota), inhabit the alimentary tract of herbivores. Although strict anaerobes, studies have suggested their capacity to retain viability after various durations of air exposure. It is currently unclear whether AGF can actively grow, and not merely survive, in redox potentials (Eh) higher than those encountered in the herbivorous gut. We evaluated the growth of two AGF strains (Orpinomyces joyonii and Testudinimyces gracilis) at various Eh levels, achieved by manipulating the concentrations of reductant (cysteine hydrochloride) in culture media. Both strains exhibited robust and sustainable growth at negative Eh (-50 mV or below). However, growth in the absence of cysteine hydrochloride (Eh value around +50 mV) was possible only for O. joyonii and only for one subcultivation. The capacity to grow at +50 mV was further confirmed in four additional taxa (Pecoramyces ruminatium, Anaeromyces mucronatus, Aklioshbmyces papillarum, and Piromyces communis), while two (Aestipascuomyces dupliciliberans and Capellomyces foraminis) failed to grow under these conditions. Our results establish the ability of AGF to grow at redox potential values higher than those encountered in their natural habitats. Such capability could contribute to efficient AGF dispersal and horizontal transmission between hosts, and could have important implications for industrial applications of AGF.

Adsorption of l-Cysteine and Cysteamine on Zinc Oxide Nanoparticles.

The reaction of l-cysteine and cysteamine hydrochloride with zinc oxide nanoparticles (ZnO NPs), by stirring excess reactant with the NPs in ethanol, has been studied by thermal gravimetric analysis (TGA), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), and Raman spectroscopy. l-Cysteine adsorption occurs via the thiol functional group, and there is no evidence for bonding via the carboxylic acid or amine functionalities. However, Raman spectroscopy and XPS reveal some protonated thiol, suggesting unbound l-cysteine is also present, as confirmed by XRD that shows the presence of l-cysteine crystallites. In the case of cysteamine/ZnO, TGA indicates that a large fraction of the sample is organic, and Raman spectroscopy reveals a dramatic shift in the C-S stretch from 796 cm-1 for unreacted cysteamine to 837 cm-1 for the reacted cysteamine. It is postulated that the acidic and chelating nature of the reaction causes dissolution of some Zn2+ ions that form a Zn(II) coordination complex with cysteamine. These studies have implications for biomolecular applications in which ZnO nanoparticles are used for biosensors, bioimaging, and drug delivery.

The potential of supramolecular synthon to develop coamorphous systems with tailored physical stability: Mechanistic insights integrating kinetics and thermodynamics

Coamorphous drug delivery systems have received increasing interest owing to their potential to improve the solubility, dissolution and bioavailability of poorly water-soluble drugs. However, the crystallization risk is one of major limitations in their application. It has been widely recognized that the coformer plays a vital role in physical stability of coamorphous formulation. Unfortunately, the screen of optimal coformer still adopts a trial-and-error method, which is time-consuming and expensive. Herein, a supramolecular synthon approach based on the interaction between functional groups, was exploited to design coamorphous systems (CMs) consisting of lurasidone hydrochloride (LH) and three coformers, saccharin (SAC), L-tryptophan (TRP), and L-cysteine hydrochloride (CYS). X-ray powder diffraction suggested the order of physical stability of the coamorphous systems was ranked as LH-CYS CM > LH-TRP CM > LH-SAC CM. The charge-assisted hydrogen bond between LH and coformer was confirmed by infrared spectroscopy and solid-state 13C NMR. Moreover, structural, electronic, and molecular interaction information, especially hydrogen bonding interactions, were quantified by theoretical calculations, including miscibility calculations, molecular dynamics simulations and quantum chemical calculations. It was revealed that LH-CYS CM exhibited the best miscibility, strongest binding energy and strongest H-bond with partially covalent character, demonstrating the significant role of supramolecular synthon in stabilizing coamorphous formulations. Interestingly, LH-TRP CM, not LH-CYS CM, exhibited the lowest molecular mobility among three coamorphous systems, which was inconsistent with their physical stability. But from thermodynamic perspective, the order of configurational entropy and physical stability of coamorphous systems was completely consistent. We shed light on the comprehensive effects of molecular mobility and configurational entropy on physical stability of coamorphous systems. Importantly, the relationship between supramolecular synthon and kinetic/thermodynamic mechanisms was also discussed, and the positive correlation between configurational entropy and intermolecular interactions was proposed in this paper. Our findings demonstrated the great potential of supramolecular synthon in designing coamorphous systems with tailored physical stability, and further provided a deeper insight into the mechanisms of physical stability of coamorphous systems.

Stimuli-responsive sulfur-containing amino acid functionalized boron nitride nanosheets as nanocarriers via improved adhesion to enhance antibacterial performance against plant diseases

Bacterial wilt caused by Ralstonia solanacearum severely impacts agricultural production, urgently requiring effective control measures. Herein, we designed a strategy via boron nitride nanosheets with enhanced adhesion ability as nanocarriers to improve the antibacterial efficacy of active ingredients. To achieve this, we utilized three sulfur-containing amino acids (SAAs), including methionine (MET), cysteine (CYS), and cystine (CYST) for the simultaneously exfoliation and functionalization of boron nitride nanosheets (BNNS) through mechanochemical method, and compared their structure–activity relationship. The obtained BNNS-SAAs exhibited size around 160–250 nm and thickness near 1.5–2.0 nm. The presence of disulfide bond (S-S) within BNNS-CYS and BNNS-CYST promoted them with the responsiveness by redox stimuli. BNNS-CYST acquired highest functionalization degree of 63.44 % among three BNNS-SAAs. And tea tree essential oil (TTO) loading capacity within BNNS-SAAs was around 36.40–37.11 %. The existence of SAAs within BNNS significantly inhibited the volatilization of TTO via nanoconfinement effect fitting to Logistic model, specially, BNNS-CYST held with slowest release rate among the BN-based carriers, due to the stronger attachment or affinity. Furthermore, BNNS-CYST-TTO exhibited the most excellent synergistic antibacterial effect with the increased inhibition zone diameter by 26.89 % against Ralstonia solanacearum in comparison with pure TTO, with the minimum inhibition concentration reduced from 1.8 mg·mL−1 to 0.6 mg·mL−1. The enhanced antibacterial mechanism was proposed based on physical disruption via strong adhesion. BNNS-SAAs also presented superior adhesion and wettability on seed and foliar surfaces, and also promoted seed germination by providing more S nutrients, and exhibited no significant cytotoxicity. Our system provides a green and effective platform response to redox stimuli to load and release essential oils for application in bacterial wilt control.

Bioreceptors’ immobilization by hydrogen bonding interactions and differential pulse voltammetry for completely label-free electrochemical biosensors

Label-free electrochemical biosensors show great potential for the development of point-of-care devices (POCDs) for environmental and clinical applications. These sensors operate with shorter analysis times and are more economic than the labelled ones. Here, four completely label-free biosensors without electron transfer mediators were developed for hepatitis B virus (HBV) detection. The approach consisted in (i) the modification of gold surfaces with cysteamine (CT) or cysteine (CS) linkers, (ii) the subsequent antibody (Ab) immobilization, either directly by hydrogen bonding (HB) interactions or by covalent bonds (CB) using additional reagents, and (iii) measuring the biosensor response by electrochemical impedance spectroscopy (EIS) and differential pulse voltammetry (DPV). The electrode surfaces at each stage of the modification process were characterised by X-ray photo-electron spectroscopy (XPS) and atomic force microscopy (AFM). The combination of Ab immobilization by HB with the DPV analysis displayed improved repeatability, lower interference to serum matrix and similar limits of detection and quantification than the traditional biosensors that immobilize the Ab via CB and use EIS as readout technique. The Ab immobilization by HB is shown as a simple, efficient and low-cost alternative to CB ones, while DPV was faster and showed better performance than EIS. The CT-HB biosensor displayed the lowest limits of detection and quantification of 0.14 and 0.46 ng/mL, respectively, a 0.46–12.5 ng/mL linear analytical range, and 100% of recovery for 1/10 human serum media during HBV surface antigen detection by DPV. Even, it preserved the initial sensing capability after 7 days of its fabrication.Graphical abstract

Potential of Vitamin D and l-Cysteine Co-supplementation to Downregulate Mammalian Target of Rapamycin: A Novel Therapeutic Approach to Diabetes.

Diabetes, a metabolic disease associated with an increased health care burden and mortality, is currently on the rise. Both upregulation of the mammalian target of rapamycin (mTOR) and decreased levels of vitamin D (VD) and l-cysteine (LC) have been associated with diabetes. The overactivation of mTOR leads to insulin desensitization and metabolic dysfunction including uncontrolled hyperglycemia. This review summarizes various studies that have shown an inhibitory effect of VD or LC on mTOR activity. Findings from preclinical studies suggest that optimizing the VD and LC status in patients with diabetes can result in mTOR suppression, which has the potential to protect these individuals from microvascular and macrovascular complications while enhancing the regulation of their blood glucose. Given this information, finding ways to suppress mTOR signaling and also increasing VD and LC status is a possible therapeutic approach that might aid patients with diabetes. Future clinical trials are needed to investigate whether VD and LC co-supplementation can successfully downregulate mTOR and can be used as adjuvant therapy in patients with diabetes.

Improvement of fluorescence properties by surface modification of CdS-ZnS quantum dots by thiol compounds and its application as a sensitive fluorescence probe for copper ion detection.

The capped CdS-ZnS quantum dots (QDs) were synthesized with various thiol capping agents of glycolic acid (TGA), mercaptosuccinic acid (MSA), and L-cysteine (LCY) and used as fluorescence probe for determination of Cu (II) ions. The method of two-level three-factor full-factorial experiment design was used to achieve the best optical fluorescence emission. Results revealed that Cu (II) ions can effectively quench the emission of QDs, and the fluorescence intensity is linearly decreased with increasing Cu (II) ion concentration. The limit of detection for CdS-ZnS@ QDs capped with TGA, MSA, and LCY was obtained at 1.15 ×10-7, 1.32 ×10-7, and 2.19 ×10-7mol L-1, respectively, with linear dynamic range of 3.13 ×10-6 to 1.41 ×10-4mol L-1. Luminescence quantum yields of CdS-ZnS@LCY, CdS-ZnS@MSA, and CdS-ZnS@TGA were obtained at 4.17, 1.92, and 2.47, respectively. Results indicated that no significant quenching occurred in the presence of the other metal ions. The binding constant (Kb) of capped CdS-ZnS@ QDs with Cu2+ and the other metal ions was also investigated and discussed. The Kb value for Cu2+ was obtained considerably more than that the other ions. This work presents a new and sensitive method for determination of Cu2+ ion.

Efficacy of L-cysteine in increasing circulatory hydrogen sulfide, nitrite, and 25(OH)VD levels in ZDF rats and in vitro treatment of H2S and NO2 in upregulating VD hydroxylase genes in monocytes

Dairy products, such as whey proteins, have been effectively utilized to enhance the effectiveness of vitamin D fortification and optimize circulating 25(OH)VD levels. Whey protein is rich in L-cysteine (LC) which is the precursor of hydrogen sulfide (H2S), enhances glutathione (GSH) biosynthesis, and promotes positive nitrogen balance. Zucker diabetic rats (ZDF) were used as a model in this study, to examine the hypothesis that LC supplementation enhances blood levels of H2S and nitrite (NO2) while reducing inflammation biomarkers. Rats were gavaged daily (orally) with either saline placebo or L-cysteine along with a high-calorie diet starting at 6 weeks of age. Fasting blood levels showed LC supplementation significantly increased circulatory levels of H2S and NO2 compared with placebo rats. LC supplementation increased plasma concentration of 25(OH)VD and vitamin C and lowered leptin and body weight gain in ZDF rats. Furthermore, to assess the impact of H2S and NO2 in raising 25(OH)VD levels, the in vitro effect of H2S/NO2 on vitamin D metabolism genes was examined using THP-1 monocytes. The exogenous H2S and NO2 treatment upregulated the relative expression of CYP2R1 and CYP27B1 genes in cultured monocytes. This study suggests a potential mechanism for the observed increase in circulating 25(OH)VD levels following L-cysteine supplementation.

Controlling Structure and Morphology of MoS2 via Sulfur Precursor for Optimized Pseudocapacitive Lithium Intercalation Hosts

AbstractMolybdenum disulfide (MoS2)‐based electrode materials can exhibit a pseudocapacitive charge storage mechanism induced by nanosized dimension of the crystalline domains, which is why control over material structure via synthesis conditions is of significance. In this study, we investigate how the use of different sulfide precursors, specifically thiourea (TU), thioacetamide (TAA), and L‐cysteine (LC), during the hydrothermal synthesis of MoS2, affects its physicochemical, and consequently, electrochemical properties. The three materials obtained exhibit distinct morphologies, ranging from micron‐sized architectures (MoS2 TU), to nanosized flakes (MoS2 TAA and LC). While all three synthesized samples exhibit pseudocapacitive Li+ intercalation properties, the capacity retention of the latter two consisting of nanosized flakes is further improved at high cycling rates. The individual charge storage properties are analyzed by operando X‐ray diffraction, dilatometry, and 3D Bode analysis, revealing a correlation between the morphology, porosity, and the electrochemical intercalation behavior of the obtained electrode materials. The results demonstrate a facile strategy to control MoS2 structure and related functionality by choice of hydrothermal synthesis precursors.

Surface Charge-Modulated Toxicity of Cysteine-Stabilized Silver Nanoparticles.

The toxicity of silver nanoparticles (AgNPs) depends on their physicochemical properties. The ongoing research aims to develop effective methods for modifying AgNPs using molecules that enable control over the processes induced by nanoparticles in both normal and cancerous cells. Application of amino acid-stabilized nanoparticles appears promising, exhibiting tunable electrokinetic properties. Therefore, this study focused on determining the influence of the surface charge of cysteine (CYS)-stabilized AgNPs on their toxicity towards human normal B (COLO-720L) and T (HUT-78) lymphocyte cell lines. CYS-AgNPs were synthesized via the chemical reduction. Transmission electron microcopy (TEM) imaging revealed that they exhibited a quasi-spherical shape with an average size of 18 ± 3 nm. CYS-AgNPs remained stable under mild acidic (pH 4.0) and alkaline (7.4 and 9.0) conditions, with an isoelectric point observed at pH 5.1. Following a 24 h treatment of lymphocytes with CYS-AgNPs, concentration-dependent alterations in cell morphology were observed. Positively charged CYS-AgNPs notably decreased lymphocyte viability. Furthermore, they exhibited grater genotoxicity and more pronounced disruption of biological membranes compared to negatively charged CYZ-AgNPs. Despite both types of AgNPs interacting similarly with fetal bovine serum (FBS) and showing comparable profiles of silver ion release, the biological assays consistently revealed that the positively charged CYS-AgNPs exerted stronger effects at all investigated cellular levels. Although both types of CYS-AgNPs have the same chemical structure in their stabilizing layers, the pH-induced alterations in their surface charge significantly affect their biological activity.

Selective detection of Co2+ by L-CyS/AA CQDs and Construction of PASS 0 gate

Since the accidental discovery of carbon quantum dots (CQDs) in 2004, they have been widely used in the field of fluorescence sensing by combining their good optical and physicochemical properties with a wide source of raw materials and a simple synthesis process. In this work, we have synthesised sulphur-doped carbon quantum dots L-CyS/AA CQDs by a one-step microwave method using L-cysteine (L-CyS) and ascorbic acid (AA) as carbon and sulphur sources. It was also analysed by fluorescence spectroscopy, X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). The prepared L-CyS/AA CQDs showed good dispersion under TEM with a spherical shape and an average particle size of 7.3 nm. L-CyS/AA CQDs were observed to be bright blue-green fluorescent with strong fluorescence (>3.5*103 a.u.) under UV light irradiation. PASS 0 logic gate operation can be achieved by controlling different fluorescent input and output. L-CyS/AA CQDs were able to achieve selective detection of Co2+ with a LOD of 63.2 μM, which provides a new method for Co2+ detection that can be used for the detection of Co2+ in real water samples.

Effects of vitamin D and L-cysteine cosupplementation on circulating bioavailable and total 25-hydroxy-vitamin D, the free/total testosterone ratio and inflammatory biomarkers in healthy vitamin D-deficient African Americans: a placebo-controlled double-blind clinical trial

BackgroundSubjects with metabolic syndrome and obesity have higher levels of inflammation with depression of the vitamin D (VD) hydroxylase/metabolising genes (CYP2R1/CYP27A1/CYP27B1/VDR) required to convert VD consumed in the diet into...

Metabolic engineering of CHO cells towards cysteine prototrophy and systems analysis of the ensuing phenotype

Chinese hamster ovary (CHO) cells require cysteine for growth and productivity in fed-batch cultures. In intensified processes, supplementation of cysteine at high concentrations is a challenge due to its limited solubility and instability in solution. Methionine can be converted to cysteine (CYS) but key enzymes, cystathionine beta-synthase (Cbs) and cystathionine gamma-lyase (Cth), are not active in CHO cells resulting in accumulation of an intermediate, homocysteine (HCY), in cell culture milieu. In this study, Cbs and Cth were overexpressed in CHO cells to confer cysteine prototrophy, i.e., the ability to grow in a cysteine free environment. These pools (CbCt) needed homocysteine and beta-mercaptoethanol (βME) to grow in CYS-free medium. To increase intracellular homocysteine levels, Gnmt was overexpressed in CbCt pools. The resultant cell pools (GnCbCt), post adaptation in CYS-free medium with decreasing residual HCY and βME levels, were able to proliferate in the HCY-free, βME-free and CYS-free environment. Interestingly, CbCt pools were also able to be adapted to grow in HCY-free and CYS-free conditions, albeit at significantly higher doubling times than GnCbCt cells, but couldn't completely adapt to βME-free conditions. Further, single cell clones derived from the GnCbCt cell pool had a wide range in expression levels of Cbs, Cth and Gnmt and, when cultivated in CYS-free fed-batch conditions, performed similarly to the wild type (WT) cell line cultivated in CYS supplemented fed-batch culture. Intracellular metabolomic analysis showed that HCY and glutathione (GSH) levels were lower in the CbCt pool in CYS-free conditions but were restored closer to WT levels in the GnCbCt cells cultivated in CYS-free conditions. Transcriptomic analysis showed that GnCbCt cells upregulated several genes encoding transporters as well as methionine catabolism and transsulfuration pathway enzymes that support these cells to biosynthesize cysteine effectively. Further, ‘omics analysis suggested CbCt pool was under ferroptotic stress in CYS-free conditions, which, when inhibited, enhanced the growth and viability of these cells in CYS-free conditions.

A surface molecular assembly-based composite inhibitor for mitigating corrosion in dynamic supercritical CO[formula omitted] aqueous environment

Supercritical CO2 (sCO2) corrosion is a persistent challenge in carbon capture, utilization, and storage (CCUS) that requires effective inhibition strategies. We present a systematic study using experimentation and modeling to investigate the inhibition behavior of a composite formulation containing Sodium Molybdate (SM), Triethanolamine Borate (TB), and L-Cysteine (LC) on X80 steel. Our in situ electrochemical studies confirm the superior performance of this ternary system, achieving a composite inhibition efficiency of over 99.86%. Surface profilometry measurements showed a roughness value as low as 33.51μm, indicating enhanced corrosion resistance and uniformity. Atomistic simulations provided mechanistic insights, revealing that LC coordinates SM and TB through favorable S-mediated interactions, optimizing the interfacial ligand network. Chemical bonding analysis indicated that this designed interface effectively suppresses corrosion through cooperative interactions, exceeding the performance of individual inhibitors. Overall, the synergistic effects of the optimized multicomponent system surpassed the efficacy expected from simply combining the individual components.

Exploring the roles of ascorbic acid/L-cysteine in boosted carbamazepine degradation by biochar-CuFe2O4/Fe2O3/CuO/peroxymonosulfate: Taguchi optimization and mechanistic studies

The present research aimed to improve the efficiency of a novel walnut shell biochar-CuFe2O4/Fe2O3/CuO (BC-CuFeO) nanocomposite for the activation of peroxymonosulfate (PMS) for the degradation of carbamazepine (CBZ), as a recalcitrant organic pollutant. Ascorbic acid (H2A) and L-cysteine (LC) were utilized to significantly increase CBZ removal efficiency in the BC-CuFeO/PMS system. An L-16 Taguchi design was applied to identify the relative significance of the operating parameters for the degradation of CBZ. In addition, both the BC-CuFeO/PMS/H2A and BC-CuFeO/PMS/LC systems demonstrated outstanding CBZ degradation performance in the presence of humic acid, sodium chloride, and sodium nitrate, respectively. The scavenging experiments indicated that 1O2, ·OH, O2•−, and SO4•− were responsible for CBZ degradation in the BC-CuFeO/PMS/H2A system, while O2•−, 1O2, and ·OH contributed to CBZ degradation in the BC-CuFeO/PMS/LC system. Furthermore, the intermediates and pathways of CBZ degradation were determined via Q-TOF-MS analysis, and the potential toxicity of the products was assessed via Toxicity Estimation Software Tool analysis. The practicality of the nanocomposites was also evaluated through the fabrication of catalytic balls and catalytic membranes, followed by the study of their stability for wastewater treatment. In conclusion, this study provides novel and promising PMS activation methods for the efficient removal of recalcitrant pollutants from wastewater.

Application of L-Cysteine Hydrochloride Delays the Ripening of Harvested Tomato Fruit.

Fruit ripening is controlled by internal factors such as hormones and genetic regulators, as well as external environmental factors. However, the impact of redox regulation on fruit ripening remains elusive. Here, we explored the effects of L-cysteine hydrochloride (LCH), an antioxidant, on tomato fruit ripening and elucidated the underlying mechanism. The application of LCH effectively delayed tomato fruit ripening, leading to the suppression of carotenoid and lycopene biosynthesis and chlorophyll degradation, and a delayed respiration peak. Moreover, LCH-treated fruit exhibited reduced hydrogen peroxide (H2O2) accumulation and increased activities of superoxide dismutase (SOD), catalase (CAT), and monodehydroascorbate reductase (MDHAR), compared with control fruit. Furthermore, transcriptome analysis revealed that a substantial number of genes related to ethylene biosynthesis (ACS2, ACS4, ACO1, ACO3), carotenoid biosynthesis (PSY, PDS, ZDS, CRTISO), cell wall degradation (PG1/2, PL, TBG4, XTH4), and ripening-related regulators (RIN, NOR, AP2a, DML2) were downregulated by LCH, resulting in delayed ripening. These findings suggest that the application of LCH delays the ripening of harvested tomato fruit by modulating the redox balance and suppressing the expression of ripening-related genes.

Solvent efficiency and role of dispersion and electrostatic forces for chiral discrimination of sulfur-containing amino acids by tetra-protonated CBPQT macrocycle

Two enantiomeric forms of amino acids in a chiral medium behave quite differently because of the different orientation of their functional groups in space. Thus, the phenomenon of chiral recognition is crucial with the focus on applications in molecular sensing and enantioselective separations. The present research work is focused on the illustration of the potential chiral recognition of a porous CBPQT4+ macrocycle for sulfur-containing amino acids, which is elucidated by the conformational energies landscape with quantitative non-covalent analysis and their electronic behaviour. Herein, we report the chiral recognition of sulfur-containing amino acids e.g., cysteine (CY), homocysteine (HCY), and methionine (MT), by tetra-protonated (4+) CBPQT macrocycle via density functional theory (DFT) calculations. Geometry optimization, thermodynamic stability, noncovalent interaction analysis, symmetry-adapted perturbation (SAPT), and electronic properties analyses are employed to characterize the chiral response of the complexes formed by CBPQT4+ with D- and L-isomers of selected amino acids. The interactive conformations of complexes indicate physisorption of amino acids through the central cavity of the macrocycle. The maximum chiral discrimination is observed in the case of D- and L-cysteine isomers, which is 3.56 kcal/mol. It is revealed that the complex; D-CY@CBPQT4+ is energetically more stable than the L-CY analogue, whereas, L-HCY and L-MT show higher stability as compared to D-type counterparts, probably due to the interaction of the thiol groups with π-electrons of macrocycle in respective stable complexes. Non-covalent interaction (NCI) analyses including, reduced density gradient-based NCI index and SAPT reveal that the methionine-based complexes show the highest attractive components e.g., electrostatic, dispersion, and induction with the lowest repulsive exchange contribution, which is followed by homocysteine and cysteine. Overall, results show that the CBPQT4+ macrocycle has an excellent ability to differentiate between L- and D-amino acids, the difference is more pronounced when the structure of amino acid is small and rigid.

G-C3N4 modified with non-precious metal Al with LSPR as an efficient visible light catalyst.

The issue of water pollution has emerged as a formidable challenge, prompting a pressing need for solutions. The utilization of metal nanoparticles with surface plasmon resonance and semiconductor composite photocatalysts is regarded as a highly effective approach to solve this problem. g-C3N4 is an effective catalyst for the degradation of organic pollutants. Its photocatalytic performance is usually enhanced by the use of the noble metal Au Ag. However, the high cost of these materials limits their application. In this study, we present the synthesis of Al NPs/g-C3N4 nanocomposites using the bridging effect of ligands. The characterized of transmission electron microscopy (TEM), X-ray diffractometer (XRD) and ultraviolet-visible spectroscopy (UV-Vis) proved that Al NPs/g-C3N4 with a wider light absorption range were successfully synthesized. The effects of ligands, (glutathione (GSH), glutamic acid (GAG), and cysteine (CYS)), Al diameter (40 to 200 nm) and the ratio of Al to g-C3N4 (1:1 to 5:1) on the photocatalytic degradation of methylene blue (MB) by Al NPs/g-C3N4 were also evaluated. The results showed that the optimum degradation efficiency of Al NPs/g-C3N4 for MB at 5 mg/L reached 100% within 60 min, which was 11 times higher than that of pure g-C3N4. The principal analysis of Al enhancing the photocatalytic performance of g-C3N4 was studied through transient photocurrent spectroscopy (TPC), electrochemical impedance spectroscopy (EIS), and steady-state transient fluorescence spectroscopy (PL). The results confirmed that hot carriers generated by localized surface plasmon resonance (LSPR) of Al nanoparticles increase the carrier concentration. In addition, the Schottky barrier generated by Al and g-C3N4 could also improve the carrier separation rate and increase the carrier lifetime. This work is expected to solve the problem of organic wastewater treatment and lay the foundation for subsequent research on photocatalysis.

Determination of ethylene-bis-dithiocarbamates and their degradation product ethylenethiourea in dry herbs by UHPLC-MS/MS.

Dithiocarbamates are a class of fungicides widely used in many countries. In this study, methods for determining the ethylene-bis-dithiocarbamate (EBDC) subclass, and their degradation product ethylenethiourea (ETU) were validated by UHPLC-MS/MS in different types of dry herbs, which can be used as food and/or medicinal purposes. Mancozeb was used in the validation of the EBDC method, where it was initially complexed with EDTA, derivatized, extracted with dimethyl sulfate in acetonitrile, magnesium sulfate (MgSO4), and sodium chloride (NaCl), and then purified using primary secondary amine (PSA). In the ETU method, L-cysteine hydrochloride monohydrate was added to the samples before extraction with acetonitrile, MgSO4, and NaCl, followed by purification with PSA. A pesticide-free blend of seven herbs (boldo, artichoke, "espinheira-santa", cat's claw, senna, chamomile, and cascara buckthorn) comprising distinct parts of the plants (leaves, bark, flowers and/or stems) was used as a control for method validation. Recoveries ranged from 79 to 113% for EBDC and 81 to 109% for ETU. Repeatability and intermediate precision were <20% for both methods. The limit of quantification was 0.03 mg kg-1 for EBDC (0.02 mg kg-1 of CS2) and ETU. The limit of detection (LOD) was set at 1/3 of the LOQ (0.01 mg kg-1 for both analytes). In total, 103 samples of 33 different dry herbs were analyzed, of which 19.4% were positive for EBDC (≥LOD), but no ETU residues were found in any of the analyzed samples. Given the absence of registered dithiocarbamates for use in the investigated herbs in Brazil, the positive results suggest potential illegal pesticide use or cross-contamination, especially considering the low concentrations detected in most samples. Although exposure to EBDC through the consumption of medicinal herbs from positive samples did not indicate a health risk to consumers, these plants must be monitored to prevent illicit pesticide usage, particularly when the herbs are intended for therapeutic purposes.

Protective effects of l-cysteine and N-acetyl-l-cysteine on boar sperm quality during hypothermic liquid storage with bovine serum albumin as a protectant

Hypothermic liquid storage at 4–5 °C has emerged as a novel approach for preserving boar semen, offering innovative possibilities for semen preservation. However, this method also presents challenges, including cold shock and excessive reactive oxygen species (ROS) production. Therefore, reducing oxidative damage induced by low temperatures becomes essential while supplementing appropriate protectants. In this study, we investigated the efficacy of Bovine Serum Albumin (BSA) compared to Polyvinylpyrrolidone (PVP) and Skim Milk Powder (SMP) in maintaining boar sperm motility and progressive motility using computer-assisted sperm analysis (CASA). Among the tested concentrations, 4 g/L of BSA exhibited the best protective effect. Subsequently, we supplemented different concentrations of l-cysteine (LC) and N-acetyl-l-cysteine (NAC) as additives in the presence of BSA as a protectant. Our results demonstrated that 1 mmol/L of LC and 0.5 mmol/L of NAC exhibited superior protection of sperm quality compared to other concentrations. Furthermore, the 1 mmol/L LC and 0.5 mmol/L NAC groups showed significantly improved plasma membrane integrity and acrosome integrity compared to the control group. These groups also exhibited enhanced antioxidant capacity, evidenced by increased mitochondrial membrane potential (MMP), ATP production, total superoxide dismutase (T-SOD) activity, total antioxidant capacity (T-AOC), glutathione (GSH), glutathione peroxidase (GSH-PX), and GPX-4 levels. Additionally, they demonstrated decreased reactive oxygen species (ROS) and malondialdehyde (MDA) levels, as well as reduced oxidized glutathione (GSSG) and glutathione reductase (GR) levels. Furthermore, LC and NAC treatment enhanced AMP-activated protein kinase (AMPK) phosphorylation. However, inhibiting AMPK using compound C did not inhibit the protective effects of LC and NAC on low-temperature preserved boar sperm. These findings suggest that 4 g/L BSA can serve as an effective protectant for hypothermic liquid storage of boar semen. Additionally, LC and NAC supplementation reduces oxidative damage by enhancing antioxidant capacity rather than through AMPK-mediated ATP supplementation. These results contribute to advancing the application of LC and NAC in hypothermic liquid storage of boar semen.