Tryptophan metabolic pathway plays a key role in the stress-induced emotional eating.

Chronic stress disrupts the emotional and energetic balance, which may lead to abnormal behaviors such as binge eating. This overeating behavior alleviating the negative emotions is called emotional eating, which may exacerbate emotional instability and lead to obesity. It is a complex and multifaceted process that has not yet been fully understood. In this study, we constructed an animal model of chronic mild stress (CMS)-induced emotional eating. The emotional eating mice were treated with tryptophan for 21 days to reveal the key role of tryptophan. Furthermore, serum-targeted metabolomics, immunohistochemical staining, qPCR and ELISA were performed. The results showed that CMS led to the binge eating behavior, accompanied by the disturbed intestinal tryptophan-derived serotonin (5-hydroxytryptamine; 5-HT) metabolic pathways. Then we found that tryptophan supplementation improved depression and anxiety-like behaviors as well as abnormal eating behaviors. Tryptophan supplementation improved the abnormal expression of appetite regulators (e.g., AgRP, OX1R, MC4R), and tryptophan supplementation also increased the tryptophan hydroxylase 2 (tph2) and 5-HT receptors in the hypothalamus of CMS mice, which indicates that the 5-HT metabolic pathway influences feeding behavior. In vitro experiments confirmed that 5-HT supplementation ameliorated corticosterone-induced aberrant expression of appetite regulators, such as AgRP and OX1R, in the hypothalamic cell line. In conclusion, our findings revealed that the tryptophan-derived 5-HT pathway plays an important role in emotional eating, especially in providing targeted therapy for stress-induced obesity.

Bimetallic Au and Pd Nanoparticles Modified WO3 Nanosheets for Enhancing the Sensitivity and Selectivity of Formaldehyde Assessment in Aquatic Products.

Formaldehyde, a common illegal additive in aquatic products, poses a threat to people's health and lives. In this study, a novel metal oxide semiconductor gas sensor based on AuPd-modified WO3 nanosheets (NSs) had been developed for the highly efficient detection of formaldehyde. WO3 NS modified with 2.0% AuPd nanoparticles showed a higher response (Ra/Rg = 94.2) to 50 ppm of formaldehyde at 210 °C, which was 36 times more than the pristine WO3 NS. In addition, the AuPd/WO3 gas sensor had a relatively short response/recovery time of 10 s/9 s for 50 ppm of formaldehyde at 210 °C, with good immunity to other interfering gases and good stability for formaldehyde. The excellent gas-sensitive performance was attributed to the chemical sensitization of Au, the electronic sensitization of Pd, and the synergistic effect of bimetallic AuPd, which facilitated the recognition and response of formaldehyde molecules. Additionally, the high sensitivity and broad application prospect of the 2.0% AuPd/WO3 NS composite-based sensor in real sample detection were also confirmed by using the above sensor for the detection of formaldehyde in aquatic products such as squid and shrimp.

Parallel Monitoring of Glucose, Free Amino Acids, and Vitamin C in Fruits Using a High-Throughput Paper-Based Sensor Modified with Poly(carboxybetaine acrylamide).

Herein, a cost-effective and portable microfluidic paper-based sensor is proposed for the simultaneous and rapid detection of glucose, free amino acids, and vitamin C in fruit. The device was constructed by embedding a poly(carboxybetaine acrylamide) (pCBAA)-modified cellulose paper chip within a hydrophobic acrylic plate. We successfully showcased the capabilities of a filter paper-based microfluidic sensor for the detection of fruit nutrients using three distinct colorimetric analyses. Within a single paper chip, we simultaneously detected glucose, free amino acids, and vitamin C in the vivid hues of cyan blue, purple, and Turnbull's blue, respectively, in three distinctive detection zones. Notably, we employed more stable silver nanoparticles for glucose detection, replacing the traditional peroxidase approach. The detection limits for glucose reached a low level of 0.049 mmol/L. Meanwhile, the detection limits for free amino acids and vitamin C were found to be 0.236 mmol/L and 0.125 mmol/L, respectively. The feasibility of the proposed sensor was validated in 13 different practical fruit samples using spectrophotometry. Cellulose paper utilizes capillary action to process trace fluids in tiny channels, and combined with pCBAA, which has superior hydrophilicity and anti-pollution properties, it greatly improves the sensitivity and practicality of paper-based sensors. Therefore, the paper-based colorimetric device is expected to provide technical support for the nutritional value assessment of fruits in the field of rapid detection.

Alkaloid Precipitant Reaction Inspired Controllable Synthesis of Mesoporous Tungsten Oxide Spheres for Biomarker Sensing.

Highly porous sensitive materials with well-defined structures and morphologies are extremely desirable for developing high-performance chemiresistive gas sensors. Herein, inspired by the classical alkaloid precipitant reaction, a robust and reliable active mesoporous nitrogen polymer sphere-directed synthesis method was demonstrated for the controllable construction of heteroatom-doped mesoporous tungsten oxide spheres. In the typical synthesis, P-doped mesoporous WO3 monodisperse spheres with radially oriented channels (P-mWO3-R) were obtained with a diameter of ∼180 nm, high specific surface area, and crystalline skeleton. The in situ-introduced P atoms could effectively adjust the coordination environment of W atoms (Wδ+-Ov), giving rise to dramatically enhanced active surface-adsorbed oxygen species and unusual metastable ε-WO3 crystallites. The P-mWO3-R spheres were applied for the sensing of 3-hydroxy-2-butanone (3H2B), a biomarker of foodborne pathogenic bacteria Listeria monocytogenes (LM). The sensor exhibited high sensitivity (Ra/Rg = 29 to 3 ppm), fast response dynamics (26/7 s), outstanding selectivity, and good long-term stability. Furthermore, the device was integrated into a wireless sensing module to realize remote real-time and precise detection of LM in practical applications, making it possible to evaluate food quality using gas sensors conveniently.

A procedure for producing an anti-AXL nanobody in E. coli.

As one of the receptors of the TAM family, AXL plays a vital role in stem cell maintenance, angiogenesis, immune escape of viruses and drug resistance against tumors. In this study, the truncated extracellular segment containing two immunoglobulin-like domains of human AXL (AXL-IG), which has been confirmed to bind growth arrest specific 6 (GAS6) by structural studies [1], was expressed in a prokaryotic expression system and then purified. Immunizing camelid with the purified AXL-IG as antigen could lead to the production of unique nanobodies composed of only variable domain of heavy chain of heavy-chain antibody (VHH), which are around 15 kD and stable. We screened out a nanobody A-LY01 specific binding to AXL-IG. We further determined the affinity of A-LY01 to AXL-IG and revealed that A-LY01 could specifically recognize full-length AXL on the surface of HEK 293T/17 cells. Our study provides appropriate support for the development of diagnostic reagents and antibody therapeutics targeting AXL.

Simultaneous and Sensitive Detection of Three Pesticides Using a Functional Poly(Sulfobetaine Methacrylate)-Coated Paper-Based Colorimetric Sensor.

Chlorpyrifos (CHL), profenofos (PRO) and cypermethrin (CYP) are widely used in combination to increase crop yields. However, these three pesticides can cause serious harm to human health and do not easily degrade. In this study, a novel visible paper sensor has been prepared successfully and different colorimetric reactions were utilized to detect the three pesticides simultaneously. The sensor was constructed by grafting a zwitterionic polymer onto a cellulose filter (CF) and placing it on a glass surface modified with PDMS. The branch shape was designed to form multiple detection areas, which were modified with specific pesticides and corresponding chromogenic reagents. The as-prepared colorimetric platform exhibited high sensitivity, a short detection time, a good linear response and a low detection limit (LOD) for the three pesticides (chlorpyrifos: y = 46.801 - 1.939x, R2 = 0.983, LOD = 0.235 mg/L; profenofos: y = 40.068 + 42.5x, R2 = 0.988, LOD = 4.891 mg/L; cypermethrin: y = 51.993 + 1.474x, R2 = 0.993, LOD = 4.053 mg/L). The comparison of the results obtained by the proposed paper sensor and those obtained by spectrophotometry further revealed the stability and reliability of the paper sensor. In particular, the color intensity of the interaction between the pesticides and coloring agents could be directly observed by the human eye. The consistency of the colorimetric/optical assay was proven in real target pesticide samples. Thus, this sensing strategy provides a portable, cost-effective, accurate and visualized paper platform, which could be suitable for application in the fruit and vegetable industry for monitoring CHL, PRO and CYP in parallel.

Hierarchical Flower-like WO3 Nanospheres Decorated with Bimetallic Au and Pd for Highly Sensitive and Selective Detection of 3-Hydroxy-2-butanone Biomarker.

Listeria monocytogenes, which is abundant in environment, can lead to many kinds of serious illnesses and even death. Nowadays, indirectly detecting the metabolite biomarker of L. monocytogenes, 3-hydroxy-2-butanone, has been verified to be an effective way to evaluate the contamination of L. monocytogenes. However, this detection approach is still limited by sensitivity, selectivity, and ppb-level detection limit. Herein, low-cost and highly sensitive and selective 3-hydroxy-2-butanone sensors have been proposed based on the bimetallic AuPd decorated hierarchical flower-like WO3 nanospheres. Notably, the 1.0 wt % AuPd-WO3 based sensors displayed the highest sensitivity (Ra/Rg = 84 @ 1 ppm) at 250 °C. In addition, the sensors showed outstanding selectivity, rapid response/recovery (8/4 s @ 10 ppm), and low detection limit (100 ppb). Furthermore, the evaluation of L. monocytogenes with high sensitivity and specificity has been achieved using 1.0 wt % AuPd-WO3 based sensors. Such a marvelous sensing performance benefits from the synergistic effect of bimetallic AuPd nanoparticles, which lead to thicker electron depletion layer and increased adsorbed oxygen species. Meanwhile, the unique hierarchical nanostructure of the flower-like WO3 nanospheres benefits the gas-sensing performance. The AuPd-WO3 nanosphere-based sensors exhibit a particular and highly selective method to detect 3-hydroxy-2-butanone, foreseeing a feasible route for the rapid and nondestructive evaluation of foodborne pathogens.

Enhanced Response for Foodborne Pathogens Detection by Au Nanoparticles Decorated ZnO Nanosheets Gas Sensor.

Listeria monocytogenes is a hazardous foodborne pathogen that is able to cause acute meningitis, encephalitis, and sepsis to humans. The efficient detection of 3-hydroxy-2-butanone, which has been verified as a biomarker for the exhalation of Listeria monocytogenes, can feasibly evaluate whether the bacteria are contained in food. Herein, we developed an outstanding 3-hydroxy-2-butanone gas sensor based on the microelectromechanical systems using Au/ZnO NS as a sensing material. In this work, ZnO nanosheets were synthesized by a hydrothermal reaction, and Au nanoparticles (~5.5 nm) were prepared via an oleylamine reduction method. Then, an ultrasonic treatment was carried out to modified Au nanoparticles onto ZnO nanosheets. The XRD, BET, TEM, and XPS were used to characterize their morphology, microstructure, catalytic structure, specific surface area, and chemical composition. The response of the 1.0% Au/ZnO NS sensors vs. 25 ppm 3-hydroxy-2-butanone was up to 174.04 at 230 °C. Moreover, these sensors presented fast response/recovery time (6 s/7 s), great selectivity, and an outstanding limit of detection (lower than 0.5 ppm). This work is full of promise for developing a nondestructive, rapid and practical sensor, which would improve Listeria monocytogenes evaluation in foods.

2H-MoS2/Co3O4 nanohybrid with type I nitroreductase-mimicking activity for the electrochemical assays of nitroaromatic compounds.

A type I nitroreductase-mimicking nanocatalyst based on 2H-MoS2/Co3O4 nanohybrids for trace nitroaromatic compounds detection is reported in this work. For the preparation of nanocatalyst, ultrathin Co3O4 nanoflakes array was in-situ grown onto 2H-MoS2 nanosheets forming three-dimensional (3D) nanohybrid with large specific surface area as well as abundant active sites. The as-prepared nanocatalyst shows a specific affinity as well as high catalytic activity towards nitroaromatic compounds. Given the favorable nitroreductase-mimicking catalytic activity of 2H-MoS2/Co3O4 nanohybrid, a sensitive and efficient electrochemical microsensor has been constructed for the detection of 2, 4, 6-trinitrotoluene (TNT). Under optimized conditions, the microsensor displayed sensitive response from µM to pM levels with a limit of detection (LOD) of 1 pM. We further employed photoelectron spectroscopy (XPS) analysis and high-performance liquid chromatography tandem mass spectrometry (HPLC-MS/MS) method to identify the nitroreductase-mimicking mechanism of 2H-MoS2/Co3O4 nanohybrids towards 2, 4, 6- TNT. It was found that the abundant oxygen vacancies in ultrathin Co3O4 nanoflakes played an essential role in determining its catalytic performance. Moreover, the developed MoS2/Co3O4 nanozyme has a lower Michaelis-Menten constant (km) than that of nature nitroreductase demonstrating a good enzymatic affinity towards its substrates, and further generating a high catalytic activity. This research not only proposed a new type of nanozyme, but also developed a portable electrochemical microsensor for the detection of 2, 4, 6-TNT.

Ultra-efficient trimethylamine gas sensor based on Au nanoparticles sensitized WO3 nanosheets for rapid assessment of seafood freshness.

Trimethylamine (TMA) is an organic amine gas used as an important index to assess the seafood freshness. In this work, an ultra-efficient trimethylamine gas sensor was constructed by ultrasonic treatment loading of Au nanoparticles (∼4 nm) on WO3 nanosheets prepared by solvothermal self-assembly method. The response of the sensor to 25 ppm TMA was as high as 217.72 (Rair/Rgas) at 300 ℃. In addition, the Au/WO3 nanosheets sensor exhibited rapid response-recovery time (8 s/6 s), low detection limit (0.5 ppm), and high selective detection of TMA. Moreover, the composition of volatiles produced by decay of Larimichthys crocea (0-15 days) was examined, which proved that the detection of TMA by the Au/WO3 sensor can evaluate the freshness of Larimichthys crocea. Such a magnificent gas sensing performance reveals that the Au/WO3 sensor has remarkable application potential in rapid and non-destructive seafood freshness assessment on the spot.

Structural and functional properties of soluble Antarctic krill proteins covalently modified by rutin.

New polyphenol-protein conjugates were successfully prepared by covalently crosslinking soluble Antarctic krill proteins with rutin (SAKPs-rutin). The physico-chemical and functional properties of SAKPs-rutin conjugates were systematically evaluated by measuring the changes in interfacial tension, structural conformation, and emulsifying ability, etc. The results showed that SAKPs-rutin conjugates possessed higher surface hydrophobicity, surface charge, and thermal denaturation temperature, and lower ß-sheet conformation compared to native SAKPs. On this basis, the interfacial tension of SAKPs-rutin conjugates was reduced, which greatly contributed to the formation of denser and more ordered networks at the oil-water interface. Meanwhile, the emulsifier endowed the fabricated high internal phase emulsions (HIPEs) with excellent physical performance and oxidative stability, evidenced by low peroxide values (POV) and malondialdehyde (MDA) after the treatment of long-term storage (15d), heating (65 °C) and UV light treatment. These findings suggest that SAKPs-rutin conjugates are a novel and promising food resource for preparing food-grade emulsions.

Fenton reaction-assisted photodynamic inactivation of calcined melamine sponge against Salmonella and its application.

Photodynamic inactivation (PDI) is an effective alternative to traditional antibiotics to broadly kill bacteria. This study aimed to develop a potent PDI system by coupling calcinated melamine sponges (CMSs) with the Fenton reaction. The results showed that CMS calcined at 350 ℃ was successfully carbonized with intact and porous structures, and it possessed excellent hydrophilicity and photothermal conversion performance. When Fe2+ was added and internalized, the Fenton reaction in which Fe2+ reacted with H2O2 in cells occurred to produce reactive oxygen species (ROS) (OH, OOH, etc.) and O2, and notably, the O2 molecules could serve as a raw material to absorb the photothermal energy of CMS to generate highly reactive 1O2. Under synergistic effects, CMS-350 coupled with Fe2+ potently inactivated > 6 Log CFU/mL (>99.9999%) of Salmonella under 201.6 J/cm2 blue LED illumination by destroying Na+/K+-ATPase and Ca2+/Mg2+-ATPase, DNA synthesis-related enzymes, cell membranes, etc. Meanwhile, the composite photocatalyst was proven to be nontoxic and could inactivate Salmonella in various foods, including vegetables (Brassica chinensis L), eggs and fresh cucumber juice. As a result, CMS coupled with the Fenton reaction greatly improves the inactivation potency of PDI against harmful bacteria.

Bimetallic Au@Pt Nanocrystal Sensitization Mesoporous α-Fe2O3 Hollow Nanocubes for Highly Sensitive and Rapid Detection of Fish Freshness at Low Temperature.

In this work, we present a new metal oxide semiconductor gas sensor for detecting trimethylamine (TMA) by bimetal Au@Pt-modified α-Fe2O3 hollow nanocubes (NCs) as sensing materials. The structure and morphological characteristics of Au@Pt/α-Fe2O3 were evaluated through multiple analyses, and their gas-sensitive performance was investigated. Compared with the pristine α-Fe2O3 NC sensor, the sensor based on Au@Pt/α-Fe2O3 NCs exhibited faster response time (5 s) and higher response (Ra/Rg = 32) toward 100 ppm TMA gas at a lower temperature (150 °C). Furthermore, we also assessed the Au@Pt/α-Fe2O3 NC sensor for detecting the freshness of Larimichthys crocea which have been observed by headspace solid-phase microextraction and gas chromatography-mass spectrometry. The high performance of the Au@Pt/α-Fe2O3 NCs is attributed to the special hollow morphology with a high specific surface area (212.9 m2/g) and the synergistic effect of the Au@Pt bimetal. The Au@Pt/α-Fe2O3 sensor shows promising application prospects in estimating seafood freshness on the spot.

Comparison on the Growth Heterogeneity of Vibrio parahaemolyticus Coupled with Strain Source and Genotype Analyses in Different Oligotrophic Conditions.

ABSTRACT: Vibrio parahaemolyticus is an important foodborne pathogen in aquatic products that can survive long term in an oligotrophic environment and maintain pathogenicity. In this study, the growth curves of 38 strains of V. parahaemolyticus (pathogenic and environmental strains) under different oligotrophic conditions (tryptone soy broth [TSB] and TSB medium diluted 2, 4, and 6 times) were simulated and their growth heterogeneities were compared. The growth kinetic parameters (maximum specific growth rate and lag time) were calculated by the modified Gompertz model. The results showed that oligotrophic conditions affected the growth variability of strains, and the coefficient of variation of all strains reached the maximum in the 4-fold dilution of TSB. Under different oligotrophic conditions, the lag time of the pathogenic strains was shorter than that of the environmental strains, whereas the maximum specific growth rate of the environmental strains was greater. This indicated that pathogenic strains were more adaptable to the nutrient-deficient environment. The analysis of different genotypes revealed that the strains with genotype tlh+/tdh+/trh- showed greater growth variability in oligotrophic environments. These results provided theoretical support for the accuracy of the risk assessment of aquatic products.

Enzyme-induced Cu2+/Cu+ conversion as the electrochemical signal for sensitive detection of ethyl carbamate.

Traditional enzyme-linked immunosorbent assay (t-ELISA) method suffers from its relatively low sensitivity or accuracy in the detection of trace level of analyte in complicated samples. In this work, to extend the application of ELISA in practical samples, a newly electrochemical immunoassay (ECIA) was developed based on an enzyme-induced Cu2+/Cu+ conversion for the determination of ethyl carbamate (EC). Wherein, three rounds of signal transformation-the catalysis of ALP enzyme, the conversion of Cu2+/Cu+ and signal output of square wave voltammetry (SWV), can be realized to obtain higher sensitivity as compared to t-ELISA. The ECIA method combines the advantages of electrochemistry and ELISA, behaving superior detection performance, such as good selectivity, high sensitivity, and low background signal. For the wine samples, the method showed a linear detection range from 2.5 nM to 2.5 × 104 nM with a limit of detection of 2.28 nM (S/N = 3), which reveals that the ECIA sensor is a promising platform for the detection of trace level of EC in practical samples.

Effects of ultrasound-assisted basic electrolyzed water (BEW) extraction on structural and functional properties of Antarctic krill (Euphausia superba) proteins.

A novel protein extraction method of ultrasound-assisted basic electrolyzed water (BEW) was proposed, and its effects on the structural and functional properties of Antarctic krill proteins were investigated. Results showed that BEW reduced 30.9% (w/w) NaOH consumption for the extraction of krill proteins, and its negative redox potential (-800 ~ -900 mV) protected the active groups (carbonyl, free sulfhydryl, etc.) of the proteins from oxidation compared to deionized water (DW). Moreover, the ultrasound-assisted BEW increased the extraction yield (9.4%), improved the solubility (8.5%), reduced the particle size (57 nm), favored the transition of α-helix and ß-turn to ß-sheet, promoted the surface hydrophobicity and disulfide bonds formation of krill proteins when compared to BEW without ultrasound. These changes contributed to the enhanced foam capacity, foam stability and emulsifying capacity of the krill proteins. Notably, all the physicochemical, structural and functional properties of the krill proteins were comparable to those extracted by the traditional ultrasound-assisted DW. This study suggests that the ultrasound-assisted BEW can be a potential candidate to extract proteins, especially offering an alternative way to produce marine proteins with high nutritional quality.

Strawberry-like SiO2/Ag nanocomposites immersed filter paper as SERS substrate for acrylamide detection.

In this work, based on the strawberry-like SiO2/Ag nanocomposites (SANC) immersed filter paper, a newly surface-enhanced Raman scattering (SERS) substrate was constructed for the detection of acrylamide (AAm) in food products. To construct filter paper-based SANC (F-SANC) SERS substrates, SiO2 nanoparticles (SNP) were firstly synthesized and acted as carriers. After that, the in-situ preparation of silver nanoparticles (Ag NP) on SNP surface was carried out to form the strawberry-like three-dimensional (3D) structure of SANC. Finally, SANC were entangled into the filter paper to produce nanoarchitecture, thus providing enhanced plasmon resonance between SANC with strong SERS signal. Under the optimized conditions, the method exhibited good performance toward AAm with a vast linear response from 0.1 nM to 50 µM (R = 0.9935), limit of detection (LOD) of 0.02 nM (S/N = 3), and the recoveries of 80.5%~105.6% for practical samples. This strategy showed good robustness in the rapid and sensitive detection of AAm, which could be a promising strategy in food analysis and verification.

Bimetallic PtCu Nanocrystal Sensitization WO3 Hollow Spheres for Highly Efficient 3-Hydroxy-2-butanone Biomarker Detection.

As a foodborne bacterium, Listeria monocytogenes (LM) can cause serious diseases and even death to weak people. 3-Hydroxy-2-butanone (3H-2B) has been proven to be a biomarker for exhalation of LM. Detection of 3H-2B is a fast and effective method for determining whether the food is infected. Herein, we present an excellent 3H-2B gas sensor based on bimetallic PtCu nanocrystal modified WO3 hollow spheres. The structure and morphology of the PtCu/WO3 were characterized, and their gas sensitivities were measured by a static testing method. The results showed that the sensor response of WO3 hollow spheres was enhanced by about 15 times after modification with bimetallic PtCu nanocrystal. The maximum response value of the PtCu/WO3 sensor to 10 ppm 3H-2B is as high as 221.2 at 110 °C. In addition, the PtCu/WO3 sensor also exhibited good selectivity to 3H-2B, fast response/recovery time (9 s/28 s), and low limit of detection (LOD < 0.5 ppm). Furthermore, the sensitivity mechanism was studied by monitoring the reaction products by gas chromatography-mass spectrometry. The excellent gas-sensing performance can be attributed to the synergy between PtCu and WO3, including the unique spillover effect of O2 on PtCu nanoparticles, the regulated depletion layer by p-type CuxO to n-type WO3, and their selective catalysis to 3H-2B. Hence, this work offers the rational design and synthesis of highly efficient sensitive materials for the detection of LM for food security.

Microevolution of Vibrio parahaemolyticus Isolated from Clinical, Acute Hepatopancreatic Necrosis Disease Infecting Shrimps, and Aquatic Production in China.

Vibrio parahaemolyticus is the leading cause of bacteria-associated foodborne diarrheal diseases and specifically causes early mortality syndrome (EMS), which is technically known as acute hepatopancreatic necrosis disease (AHPND), a serious threat to shrimp aquaculture. To investigate the genetic and evolutionary relationships of V. parahaemolyticus in China, 184 isolates from clinical samples (VPC, n=40), AHPND-infected shrimp (VPE, n=10), and various aquatic production sources (VPF, n=134) were collected and evaluated by a multilocus sequence analysis (MLST). Furthermore, the presence of potential virulence factors (tlh, tdh, and trh) and single nucleotide polymorphisms (SNPs) in V. parahaemolyticus isolates was assessed using genomic sequencing. Analyses of virulence factors revealed that the majority of VPC isolates (97.5%) possessed the tdh and/or trh genes, while most of the VPF isolates (83.58%) did not encode hemolysin genes. Therefore, we hypothesized that the environment is a potential reservoir that promotes horizontal DNA transfer, which drives evolutionary change that, in turn, leads to the emergence of novel, potentially pathogenic strains. Phylogenetic analyses identified VPF-112 as a non-pathogenic maternal strain isolated from aquatic products and showed that it had a relatively high evolutionary status. All VPE strains and some VPC strains were grouped into several small subgroups and evenly distributed on phylogenetic trees. Anthropogenic activities and environmental selective pressure may be important factors influencing the process of transforming strains from non-pathogenic to pathogenic bacteria.

Controlled Synthesis of Pt Doped SnO2 Mesoporous Hollow Nanospheres for Highly Selective and Rapidly Detection of 3-Hydroxy-2-Butanone Biomarker.

Listeria monocytogenes (L. monocytogenes) has been recognized as one of the extremely hazardous and potentially life-threatening food-borne pathogens, its real-time monitoring is of great importance to human health. Herein, a simple and effective method based on platinum sensitized tin dioxide semiconductor gas sensors has been proposed for selective and rapid detection of L. monocytogenes. Pt doped SnO2 nanospheres with particular mesoporous hollow structure have been synthesized successfully through a robust and template-free approach and used for the detection of 3-hydroxy-2-butanone biomarker of L. monocytogenes. The steady crystal structure, unique micromorphology, good monodispersit, and large specific surface area of the obtained materials have been confirmed by X-ray diffraction (XRD), Raman spectroscopy, Scanning Electron Microscopy (SEM), Transmission Electron Microscopy (TEM), X-ray Photoelectron Spectroscopy (XPS), Brunauer-Emmett-Teller (BET), and Photoluminescence spectra (PL). Pt doped SnO2 mesoporous hollow nanosphere sensors reach the maximum response of 3-hydroxy-2-butanone at 250°C. Remarkably, sensors based on SnO2 mesoporous hollow nanospheres with 0.16 wt% Pt dopant exhibit excellent sensitivity (Rair/Rgas = 48.69) and short response/recovery time (11/20 s, respectively) to 10 ppm 3-hydroxy-2-butanone at the optimum working temperature. Moreover, 0.16 wt% Pt doped SnO2 gas sensors also present particularly low limit of detection (LOD = 0.5 ppm), superb long-term stability and prominent selectivity to 3-hydroxy-2-butanone. Such a gas sensor with high sensing performance foresees its tremendous application prospects for accurate and efficient detection of foodborne pathogens for the food security and public health.