High-Coverage UHPLC-MS/MS Analysis of 67 Mycotoxins in Plasma for Male Infertility Exposure Studies.

Mycotoxins are a class of exogenous metabolites that are major contributors to foodborne diseases and pose a potential threat to human health. However, little attention has been paid to trace mycotoxin co-exposure situations in vivo. To address this, we devised a novel analytical strategy, both highly sensitive and comprehensive, for quantifying 67 mycotoxins in human plasma samples. This method employs isotope dilution mass spectrometry (IDMS) for approximately 40% of the analytes and utilizes internal standard quantification for the rest. The mycotoxins were classified into three categories according to their physicochemical properties, facilitating the optimization of extraction and detection parameters to improve analytical performance. The lowest limits of detection and quantitation were 0.001-0.5 µg/L and 0.002-1 µg/L, respectively, the intra-day precision ranged from 1.8% to 11.9% RSD, and the intra-day trueness ranged from 82.7-116.6% for all mycotoxins except Ecl, DH-LYS, PCA, and EnA (66.4-129.8%), showing good analytical performance of the method for biomonitoring. A total of 40 mycotoxins (including 24 emerging mycotoxins) were detected in 184 plasma samples (89 from infertile males and 95 from healthy males) using the proposed method, emphasizing the widespread exposure of humans to both traditional and emerging mycotoxins. The most frequently detected mycotoxins were ochratoxin A, ochratoxin B, enniatin B, and citrinin. The incidence of exposure to multiple mycotoxins was significantly higher in infertile males than in healthy subjects, particularly levels of ochratoxin A, ochratoxin B, and citrinin, which were significantly increased. It is necessary to carry out more extensive biological monitoring to provide data support for further study of the relationship between mycotoxins and male infertility.

Visible light-responsive polylactic acid@pullulan-chitosan/homojunction g-C3N4 bilayer antimicrobial films for fruit preservation.

The development of novel packaging materials with antimicrobial properties is crucial in preventing the microbial-induced spoilage of fruits, vegetables, and foodborne illnesses. In this study, homojunction g-C3N4 (HCN) photocatalysts with excellent photocatalytic performance were incorporated into a matrix consisting of pullulan/chitosan (Pul/CS). These photocatalysts were then electrostatically spun onto polylactic acid (PLA) films to fabricate PLA@Pul/CS/HCN nanofibrous composite films. The design of the bilayer films aimed to combine the physical properties of PLA film with the excellent antibacterial properties of nanofiber films, thereby achieving synergistic advantages. The incorporation of the HCN photocatalysts resulted in enhanced hydrophobicity, barrier function, and mechanical properties of the composite films. Under visible light irradiation, the PLA@Pul/CS/HCN films exhibited approximately 3.43 log and 3.11 log reductions of Escherichia coli and methicillin-resistant Staphylococcus aureus (MRSA), respectively, within 2 h. The excellent antimicrobial performance could be attributed to the synergistic effect of CS and the release of reactive oxygen species (ROS) from HCN. Moreover, the strawberries packaged in the PLA@Pul/CS/HCN film demonstrated diminished quality degradation and a prolonged shelf life following visible light irradiation treatment. This study will provide new insights into the exploration of safe and efficient antimicrobial food packaging.

Metabolic transformation of cyclopiazonic acid in liver microsomes from different species based on UPLC-Q/TOF-MS.

To investigate the metabolic transformation of cyclopiazonic acid (CPA) in the liver of different species and to supplement accurate risk assessment information, the metabolism of CPA in liver microsomes from four animals and humans was studied using the ultra-high-performance liquid chromatography-quadrupole/time-of-flight method. The results showed that a total of four metabolites were obtained, and dehydrogenation, hydroxylation, methylation, and glucuronidation were identified as the main metabolic pathways of CPA. Rat liver microsomes exhibited the highest metabolic capacity for CPA, with dehydrogenated (C20H18N2O3) and glucuronic acid-conjugated (C26H28N2O10) metabolites identified in all liver microsomes except chicken, indicating significant species metabolic differences. Moreover, C20H18N2O3 was only detected in the incubation system with cytochromes P450 3A4 (CYP3A4). The hydroxylated (C20H20N2O4) and methylated (C21H22N2O3) metabolites were detected in all incubation systems except for the CYP2C9, with CYP3A4 demonstrating the strongest metabolic capacity. The "cocktail" probe drug method showed that CPA exhibited a moderate inhibitory effect on the CYP3A4 (IC50 value = 8.658 µM), indicating that the substrate had a negative effect on enzyme activity. Our results provide new insights to understand the biotransformation profile of CPA in animals and humans.

Restricted-Access Media Column Switching Online Solid-Phase Extraction UHPLC-MS/MS for the Determination of Seven Type B Trichothecenes in Whole-Grain Preprocessed Foods and Human Exposure Risk Assessment.

With increasing health awareness and the accelerating pace of life, whole-grain prepared foods have gained popularity due to their health benefits and convenience. However, the potential risk of type B trichothecene toxins has also increased, and these mycotoxins in such foods are rarely regulated. In this study, a quantitative method combining a single-valve dual-column automatic online solid-phase extraction system with ultra-high-performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) was developed for the first time using restricted-access media columns. This method can simultaneously determine trace residues of seven type B trichothecenes within 15 min. The method is convenient, sensitive (limit of detection and quantification of 0.05-0.6 µg/kg and 0.15-2 µg/kg, respectively), accurate (recovery rates of 90.3%-106.6%, relative standard deviation < 4.3%), and robust (>1000 times). The established method was applied to 160 prepared food samples of eight categories sold in China. At least one toxin was detected in 70% of the samples. Whole-wheat dumpling wrappers had the highest contamination rate (95%) and the highest total content of type B trichothecenes in a single sample (2077.3 µg/kg). Exposure risk assessment indicated that the contamination of whole-grain prepared foods has been underestimated. The total health risk index of whole-wheat dumpling wrappers, which are susceptible to deoxynivalenol, reached 136.41%, posing a significant threat to human health. Effective measures urgently need to be taken to control this risk.

Antimicrobial carbon dots/pectin-based hydrogel for promoting healing processes in multidrug-resistant bacteria-infected wounds.

Multidrug-resistant (MDR) bacterial infections have become a significant threat to global healthcare systems. Here, we developed a highly efficient antimicrobial hydrogel using environmentally friendly garlic carbon dots, pectin, and acrylic acid. The hydrogel had a porous three-dimensional network structure, which endowed it with good mechanical properties and compression recovery performance. The hydrogel could adhere closely to skin tissues and had an equilibrium swelling ratio of 6.21, indicating its potential as a wound dressing. In particular, the bactericidal efficacy following 24-h contact against two MDR bacteria could exceed 99.99 %. When the hydrogel was applied to epidermal wounds infected with methicillin-resistant Staphylococcus aureus (MRSA) on mice, a remarkable healing rate of 93.29 % was observed after 10 days. This was better than the effectiveness of the traditionally used antibiotic kanamycin, which resulted in a healing rate of 70.36 %. In vitro cytotoxicity testing and hemolysis assay demonstrated a high biocompatibility. This was further proved by the in vivo assay where no toxic side effects were observed on the heart, liver, spleen, lung, or kidney of mice. This eco-friendly and easy-to-prepare food-inspired hydrogel provides an idea for the rational use of food and food by-products as a wound dressing to control MDR bacterial infections.

Double phage displayed peptides co-targeting-based biosensor with signal enhancement activity for colorimetric detection of Staphylococcus aureus.

The development of simple, fast, sensitive, and specific strategies for the detection of foodborne pathogenic bacteria is crucial for ensuring food safety and promoting human health. Currently, detection methods for Staphylococcus aureus still suffer from issues such as low specificity and low sensitivity. To address this problem, we proposed a sensitivity enhancement strategy based on double phage-displayed peptides (PDPs) co-targeting. Firstly, we screened two PDPs and analyzed their binding mechanisms through fluorescent localization, pull-down assay, and molecular docking. The two PDPs target S. aureus by binding to specific proteins on its outer membrane. Based on this phenomenon, a convenient and sensitive double PDPs colorimetric biosensor was developed. Double thiol-modified phage-displayed peptides (PDP-SH) enhance the aggregation of gold nanoparticles (AuNPs), whereas the specific interaction between the double PDPs and bacteria inhibits the aggregation of AuNPs, resulting in an increased visible color change before and after the addition of bacteria. This one-step colorimetric approach displayed a high sensitivity of 2.35 CFU/mL and a wide detection range from 10-2 × 108 CFU/mL. The combination with smartphone-based image analysis improved the portability of this method. This strategy achieves the straightforward, highly sensitive and portable detection of pathogenic bacteria.

Recent advances in biosynthesis of mycotoxin-degrading enzymes and their applications in food and feed.

Mycotoxins are secondary metabolites produced by fungi in food and feed, which can cause serious health problems. Bioenzymatic degradation is gaining increasing popularity due to its high specificity, gentle degradation conditions, and environmental friendliness. We reviewed recently reported biosynthetic mycotoxin-degrading enzymes, traditional and novel expression systems, enzyme optimization strategies, food and feed applications, safety evaluation of both degrading enzymes and degradation products, and commercialization potentials. Special emphasis is given to the novel expression systems, advanced optimization strategies, and safety considerations for industrial use. Over ten types of recombinases such as oxidoreductase and hydrolase have been studied in the enzymatic hydrolysis of mycotoxins. Besides traditional expression system of Escherichia coli and yeasts, these enzymes can also be expressed in novel systems such as Bacillus subtilis and lactic acid bacteria. To meet the requirements of industrial applications in terms of degradation efficacy and stability, genetic engineering and computational tools are used to optimize enzymatic expression. Currently, registration and technical difficulties have restricted commercial application of mycotoxin-degrading enzymes. To overcome these obstacles, systematic safety evaluation of both biosynthetic enzymes and their degradation products, in-depth understanding of degradation mechanisms and a comprehensive evaluation of their impact on food and feed quality are urgently needed.

Exploring the impact of fungal spores from agricultural environments on the mice lung microbiome and metabolic profile.

Exposure to particulate matter (PM) from agricultural environments has been extensively reported to cause respiratory health concerns in both animals and agricultural workers. Furthermore, PM from agricultural environments, containing fungal spores, has emerged as a significant threat to public health and the environment. Despite its potential toxicity, the impact of fungal spores present in PM from agricultural environments on the lung microbiome and metabolic profile is not well understood. To address this gap in knowledge, we developed a mice model of immunodeficiency using cyclophosphamide and subsequently exposed the mice to fungal spores via the trachea. By utilizing metabolomics techniques and 16 S rRNA sequencing, we conducted a comprehensive investigation into the alterations in the lung microbiome and metabolic profile of mice exposed to fungal spores. Our study uncovered significant modifications in both the lung microbiome and metabolic profile post-exposure to fungal spores. Additionally, fungal spore exposure elicited noticeable changes in α and ß diversity, with these microorganisms being closely associated with inflammatory factors. Employing non-targeted metabolomics analysis via GC-TOF-MS, a total of 215 metabolites were identified, among which 42 exhibited significant differences. These metabolites are linked to various metabolic pathways, with amino sugar and nucleotide sugar metabolism, as well as galactose metabolism, standing out as the most notable pathways. Cysteine and methionine metabolism, along with glycine, serine and threonine metabolism, emerged as particularly crucial pathways. Moreover, these metabolites demonstrated a strong correlation with inflammatory factors and exhibited significant associations with microbial production. Overall, our findings suggest that disruptions to the microbiome and metabolome may hold substantial relevance in the mechanism underlying fungal spore-induced lung damage in mice.

Sleep Promotion by 3-Hydroxy-4-Iminobutyric Acid in Walnut Diaphragma juglandis Fructus.

Insufficient sleep can produce a multitude of deleterious repercussions on various domains of human well-being. Concomitantly, the walnut (Juglans mandshurica) confers numerous salutary biological activities pertaining to sleep. Nevertheless, the sedative and hypnotic capacities of walnut's functional constituents remain obscure. In this investigation, we analyzed the sedative and hypnotic components of the walnut Diaphragma juglandis fructus and innovatively discovered a compound, defined as 3-hydroxy-4-iminobutyric acid (HIBA), which disrupts motor activity and enhances sleep duration by regulating the neurotransmitters (GABA, DA, etc.) within the brain and serum of mice. Subsequently, a metabolomics approach of the serum, basal ganglia, hypothalamus, and hippocampus as well as the gut microbiota was undertaken to unravel the underlying molecular mechanisms of sleep promotion. Our data reveal that HIBA can regulate the metabolism of basal ganglia (sphingolipids, acylcarnitines, etc.), possibly in relation to HIBA's influence on the gut microbiome (Muribaculum, Bacteroides, Lactobacillus, etc.). Therefore, we introduce a novel natural product, HIBA, and explicate the modulation of sleep promotion in mice based on the microbiota-gut-brain axis. This study contributes fresh insights toward natural product-based sleep research.

Metabolic reprogramming of the glutathione biosynthesis modulates the resistance of Salmonella Derby to ceftriaxone.

Salmonella, a foodborne pathogen, has become a major public health concern because of its widespread drug resistance, including resistance to multiple drugs such as third-generation cephalosporin, ceftriaxone (CRO). However, the metabolic profile changes and associated mechanisms engendered by cephalosporin-resistant mutations remain uncharted. In this study, we have employed the LC-MS/MS metabolomics platform to determine the metabolic profiles of 138 strains of Salmonella. Our results show that metabolic profiles correspond to specific serotypes, sources, processing stages, and antibiotic resistance patterns. Notably, we observed that Salmonella Derby (S. Derby) with drug resistance to CRO has a different metabolic status with changes in glutathione biosynthesis. Specifically, glutathione oxidized (GSSG) and citrulline abundances are greatly suppressed in CRO-resistant S. Derby. Furthermore, exogenous GSSG or citrulline, but not glutathione reduced (GSH), restored the susceptibility of multidrug-resistant S. Derby to CRO. This study establishes a strategy based on functional metabolomics to manage the survival of antibiotic-resistant bacteria.

Combined metabolomics and transcriptomics analysis reveals the mechanism of antibiotic resistance of Salmonella enterica serovar Typhimurium after acidic stress.

Drug-resistant Salmonella is widely distributed in the meat production chain, endangering food safety and public health. Acidification of meat products during processing can induce acid stress, which may alter antibiotic resistance. Our study investigated the effects of acid stress on the antibiotic resistance and metabolic profile of Salmonella Typhimurium, and explored the underlying mechanisms using metabolomic and transcriptomic analysis. We found that acid-stressed 14028s was more sensitive to small molecule hydrophobic antibiotics (SMHA) while more resistant to meropenem (MERO). Metabolomic analysis revealed that enhanced sensitivity to SMHA was correlated with increased purine metabolism and tricarboxylic acid cycle. Transcriptomic analysis revealed the downregulation of chemotaxis-related genes, which are also associated with SMHA sensitivity. We also found a significant downregulation of the ompF gene, which encodes a major outer membrane protein OmpF of Salmonella. The decreased expression of OmpF porin hindered the influx of MERO, leading to enhanced resistance of the bacteria to the drug. Our findings contribute to greatly improve the understanding of the relationship between Salmonella metabolism, gene expression, and changes in drug resistance after acid stress, while providing a structural framework for exploring the relationship between bacterial stress responses and antibiotic resistance.

Long-term chronic food-derived arsenic exposure induce the urinary system metabolic dysfunction in mice.

The consumption of rice contaminated with arsenic on a long-term basis has emerged as a pressing public health issue of global significance. Arsenic-induced urinary injury, particularly kidney damage, has received widespread attention. In this study, mice model under long-term arsenic exposure was established, mouse were exposed to rice arsenic (30 mg/kg) for 14 months. Changes of related metabolites were observed based on kidney metabolomics and lipidomics, and major biomarkers were screened by urine metabolomics. The results showed that phosphatidylethanolamine (PE) was significantly increased and phosphatidycholine (PC) and phosphatidylglycerol (PG) were significantly reduced after arsenic exposure, leading to related downstream lipid metabolism disorders. The metabolic pathways for amino acid and energy were observed to be impacted. In addition, metabolic disorders due to arsenic exposure may be associated with inherited neurometabolic disorders, such as D-2-hydroxyglutaric aciduria (D-2-HGA), and pyruvate carboxylase deficiency (PCD), which is predicted based on significant difference biomarkers (2-oxoglutarate, malic acid, and succinic acid) screened for urine. This study elucidates the mechanism of toxicity in the urinary system induced by arsenic exposure at nearly half life cycle, which furnishes crucial scientific evidence pertaining to the toxicity and risk evaluation associated with chronic exposure to the arsenic.

Effect of Baking Conditions and Glucose Addition on the Changes and Transformations between Fumonisins and their Covert Forms during Corn Crisp Processing.

This study investigated the impact of baking factors on fumonisin B (FB) levels in corn crisps using ultraperformance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS). The results indicated that both free and total FBs decreased with an increase in baking time and temperature, while glucose addition facilitated this reduction. Total FBs reached the lowest value of 109.69 ng/g after 50 min of baking. Conversely, covert FBs increased with baking time but decreased with glucose addition at high temperatures. Additionally, the highest levels of hydrolyzed FBs (HFBs), N-(carboxymethyl) FB1, and N-(deoxy-d-fructos-1-yl) FB1 occurred 20 min before decomposing and were detected in corn crisps baked at 160 °C. Glucose addition accelerated the transformation between free and covert FBs. Furthermore, the inhibition of NCM FB1 accumulation was accompanied by the promotion of NDF FB1 accumulation during corn crisp processing. These findings provide insights into the effect of baking factors on FBs and suggest strategies for reducing FB contamination in corn crisps.

A Simplified Amplification-Free Strategy with Lyophilized CRISPR-CcrRNA System for Drug-Resistant Salmonella Detection.

Drug resistance in pathogenic bacteria has become a major threat to global health. The misuse of antibiotics has increased the number of resistant bacteria in the absence of rapid, accurate, and cost-effective diagnostic tools. Here, an amplification-free CRISPR-Cas12a time-resolved fluorescence immunochromatographic assay (AFC-TRFIA) is used to detect drug-resistant Salmonella. Multi-locus targeting in combination crRNA (CcrRNA) is 27-fold more sensitive than a standalone crRNA system. The lyophilized CRISPR system further simplifies the operation and enables one-pot detection. Induction of nucleic acid fixation via differentially charged interactions reduced the time and cost required for flowmetric chromatography with enhanced stability. The induction of nucleic acid fixation via differentially charged interactions reduces the time and cost required for flowmetric chromatography with enhanced stability. The platform developed for the detection of drug-resistant Salmonella has an ultra-sensitive detection limit of 84 CFU mL-1 within 30 min, with good linearity in the range of 102 -106 CFU mL-1 . In real-world applications, spiked recoveries range from 76.22% to 145.91%, with a coefficient of variation less than 10.59%. AFC-TRFIA offers a cost-effective, sensitive, and virtually equipment-independent platform for preventing foodborne illnesses, screening for drug-resistant Salmonella, and guiding clinical use.

Rapid generation of high-quality recombinant antibodies using an Expi293F expression system for a 17 ß-estradiol immunoassay.

The rapid generation of high-quality target antibodies is essential for research employing immunoassays. The use of recombinant antibody technology that relies on genetic engineering is one such means to produce high-quality antibodies. Obtaining the gene sequence information of immunoglobulin is a prerequisite for the preparation of genetically engineered antibodies. At present, many researchers have shared their amino acid sequence data for various high-performance antibodies and their related properties. In this study, we obtained the protein sequence of a variable region of a 17 ß-estradiol (E2) antibody from the Protein Data Bank (PDB) and subsequently constructed heavy (H) and light (L) chain expression vectors through codon optimization. The transient expression, purification, and performance identification of the immunoglobulin G (IgG), antigen-binding fragment (Fab), and single-chain variable fragment (scFv) antibodies were carried out, respectively. The effects of the different expression vectors on the expression yield of the IgG antibody were further compared. Among them, the expression yield based on the pTT5 vector was the highest, reaching 27 mg/L. Based on the expressed IgG and Fab antibodies, an indirect competitive enzyme-linked immunosorbent assay (ic-ELISA) standard curve of E2 was constructed, and the half-maximal inhibitory concentrations (IC50) for these two antibodies were determined to be 0.129 ng/mL and 0.188 ng/mL, respectively. In addition, an immunochromatographic assay (ICA) based on the IgG antibody was constructed with an IC50 of 3.7 ng/mL. Therefore, in featuring the advantages of simplicity, high efficiency, rapid obtainment, and high titer yield, we propose the system for the rapid generation of high-quality recombinant antibodies by reusing the published antibody information and show that it has good implementation prospects in improving upon existing immunoassay techniques.

A highly sensitive fluorescence immunochromatography strip for thiacloprid in fruits and vegetables using recombinant antibodies.

Thiacloprid (TCL) is a neonicotinoid insecticide. Its widespread use has led to high levels of residue in fruits and vegetables. Hence, it is important to detect TCL rapidly, accurately, and sensitively in fruits and vegetables. Recombinant antibodies (rAbs) can be synthesized rapidly with little batch-to-batch variation. In this study, recombinant single-chain variable fragment (scFv) antibody and full-length recombinant antibody against TCL were produced using three different expression systems (E. coli, yeast, and mammalian cell). The results of SDS-PAGE and non - competitive enzyme-linked immunosorbent assay (ELISA) indicated that the full-length rAb exhibited promising characteristics, and the IC50 value of indirect competitive ELISA (ic-ELISA) was 2.63 µg L-1. However, recombinant scFv antibody had little affinity for the antigen. To understand antibody recognition, the three-dimensional (3D) model of the variable fragment (Fv) was built via homologous modeling. The interaction between Fv and TCL was analyzed via molecular docking and the results of molecular docking showed that VAL-158, ALA-211, PHE-220, TRP-218, TRP-49, and ILE-100 were mainly responsible for antibody recognition. In addition, a time-resolved fluorescent microsphere-immunochromatographic test strip (TRFM-ICTS) was developed with a linear range and limit of detection of 0.01-10 ng mL-1 and 0.003 ng mL-1 within 15 min under optimal conditions. The IC50 value was 4.268 ng mL-1, and the recovery ranged between 79.4% and 118.6%, which was consistent with HPLC-MS. The TRFM-ICTS has great advantages in sensitivity and applicability.

Efficient Biodegradation of Patulin by Aspergillus niger FS10 and Metabolic Response of Degrading Strain.

Patulin, a mycotoxin commonly found in fruits and derived products, causes serious health problems for humans and animals worldwide. Several microbial strains have been observed to possess the ability to effectively remove patulin. However, these methods are presently associated with disadvantages such as low degradation efficiency and an unclear biodegradation mechanism. In the current study, the characteristics of patulin degradation via Aspergillus niger FS10 were evaluated, and the mechanisms involved were analyzed using metabolomics technologies. The results showed that the suspension of A. niger FS10 could degrade 94.72% of patulin within 36 h. The moment concentration pf patulin was 0.116 µg/mL, and the detection limit value was 0.01 µg/mL. In addition, the patulin content was reduced to levels below the detection limit within 48 h. A. niger FS10 mainly degrades patulin by producing intracellular enzymes, which can convert patulin into ascladiol. This degradation method can effectively reduce the damage caused by patulin to HepG2 cells. In addition, the patulin treatment significantly affects the pentose phosphate pathway and the glutathione pathway. These two metabolic pathways are speculated to be closely related to patulin degradation via A. niger FS10. The incubation of A. niger FS10 with patulin-contaminated apple pomace can not only eliminate patulin but also increase the utilization of apple pomace. Therefore, our research results provide a new method for addressing patulin contamination in the food and feed industries.

Positive effects of steamed Polygonatum sibiricum polysaccharides including a glucofructan on fatty acids and intestinal microflora.

Steam-processed Polygonatum sibiricum (PS) has been used as food for thousands of years. However, fewer studies concentrated on the effects of polysaccharides (SPSP) from the steamed PS on the intestinal tract. With fermentation in vitro, we investigated the impact of SPSP on the fatty acids and microbiotas. Results showed significant increases in short-chain fatty acids (SCFAs) like acetic acid and propionic acid, and long-chain fatty acids (LCFAs) like cis, cis, cis-9,12,15-linolenic acid, cis-6-octadecenoic acid, and cis-9-octadecenoic acid after 12 h. The positive-associated beneficial microbiotas were observed with proliferation like Parabacteroides and Bifidobacterium. Harmful microbiota like Shigella showed decreased abundance. Further, a small molecule polysaccharide was separated from the SPSP with the structure of one glucose and ten fructose, which significantly increased SCFAs and LCFAs contents during fermentation. The potential benefits of SPSP were proved by the analysis of fatty acid levels and the intestinal microbiotas during fermentation.

Carbon dots cooperatively modulating photocatalytic performance and surface charge of O-doped g-C3N4 for efficient water disinfection.

The emergence of widespread microbial contamination and drug-resistant bacteria in the water environment poses a severe threat to public health. Photocatalysis is considered an efficient, energy-saving, and cost-effective disinfection strategy for effectively removing microbial contamination from water bodies. In this paper, a metal-free O-doped g-C3N4/carbon dots (O-CN/CDs) nanosheet photocatalysts are prepared in coordination with various modification strategies, which results in a considerable improvement in photocatalytic disinfection activity compared to bulk g-C3N4 (B-CN). First, O-doping and morphology modulation are achieved simultaneously with hydrothermal treatment, which not only hinders the recombination of photogenerated hole-electron pairs, but also enables the exposure of more active centers. Subsequently, loading of CDs onto O-CN nanosheets by electrostatic self-assembly increases the production of photogenerated hole-electron pairs by expanding the visible light absorption region and promoted the separation of photogenerated carriers by trapping photogenerated electrons. Interestingly, the loading of CDs changes the charge on the surface of the composite photocatalyst from negative to positive, making it easier for the active species to come in contact with bacteria, and thus improving bacterial disinfection performance. Under visible light irradiation, the inactivation efficiency of optimized O-CN/CDs against methicillin-resistant Staphylococcus aureus (MRSA) is log(C/C0) = 4.08, approximately 9 times higher than that of B-CN. The main active species inactivating bacteria are superoxide anions radicals (•O2-) and photogenerated holes, and their attack causes damage to the membrane wall structure and leakage of intracellular components. Additionally, the feasibility of the as-prepared photocatalysts in water disinfection in real environments was confirmed by photocatalytic disinfection experiments in successive recovery cycles and in practical lake water.

Cell-Based Metabolomics Approach for Anticipating and Investigating Cytotoxicity of Gold Nanorods.

Despite the increasing application of gold nanoparticles, there has been little assessment of biological system toxicity to evaluate their potential impact on human health. In this study, the human hepatoma cell line (Hep G2) was used in a metabolomics approach to study the effects of shape, time, and dose of gold nanorods (GNRs). Using optimized parameters for chromatography and mass spectrometry, the metabolites detected by GC-MS were processed with MS DIAL and identified with Fiehnlib. Key metabolic pathways affected by GNRs were identified by endo-metabolic profiling of cells mixed with GNRs of varying shape while varying the dose and time of exposure. The shape of GNRs affected cytotoxicity, and short GNR (GNR-S) triggered disorder of cell metabolism. High concentrations of GNRs caused more significant toxicity. The cytotoxicity and bioTEM results illustrated that the mitochondria toxicity, as the main cytotoxicity of GNRs, caused declining cytoprotective ability. The mitochondrial dysfunction disrupted alanine, aspartate, glutamate, arginine, and proline metabolism, with amino acid synthesis generally downregulated. However, the efflux function of cells can exclude GNRs extracellularly within 24 h, resulting in reduced cell mitochondrial metabolic toxicity and allowing metabolic disorders to recover to normal function.