Rapid and Facile Synthesis of Gold Trisoctahedrons for Surface-Enhanced Raman Spectroscopy and Refractive Index Sensing.

Au trisoctahedrons (TOHs) with sharp tips and high-index facets have exceptional properties for diverse applications, such as plasmon-enhanced spectroscopies, catalysis, sensing, and biomedicine. However, the synthesis of Au TOHs remains challenging, and most reported synthetic methods are time-consuming or involve complex steps, hindering the exploration of their potential applications. Herein, we present a facile and fast approach to prepare Au TOHs with high uniformity and good control over the final size and shape, all within less than 10 min of synthesis, for surface-enhanced Raman spectroscopy (SERS) and refractive index sensing. The size of the Au TOHs can be easily tailored over a wide range, from 39 to 268 nm, allowing a tuning of the plasmon resonance at wavelengths from visible to near-infrared regions. The exposed facets of the Au TOHs can also be varied by controlling the growth temperatures. The wide tunability of size and exposed facets of Au TOHs can greatly broaden the range of their applications. We have also encapsulated Au TOHs with zeolite imidazolate framework (ZIF-8), obtaining core-shell hybrid structures. With the ability to tune Au TOH size, we further assessed their SERS performances in function of their size by detecting 2-NaT in solution, exhibiting enhancement factors of the order of 105 with higher values when the LSPR is blue-shifted from the laser excitation wavelength. Au TOHs have been also compared for refractive index sensing applications against Au nanospheres, revealing Au TOHs as better candidates. Overall, this facile and fast method for synthesizing Au TOHs with tunable size and exposed facets simplifies the path toward the exploration of properties and applications of this highly symmetrical and high-index nanostructure.

Synthesis and Screening of Chemical Agents Targeting Viral Protein Genome-Linked Protein of Telosma Mosaic Virus.

The viral protein genome-linked protein (VPg) of telosma mosaic virus (TeMV) plays an important role in viral reproduction. In this study, the expression conditions of TeMV VPg were explored. A series of novel benzenesulfonamide derivatives were synthesized. The binding sites of the target compounds and TeMV VPg were studied by molecular docking, and the interaction was verified by microscale thermophoresis. The study revealed that the optimal expression conditions for TeMV VPg were in Escherichia coli Rosetta with IPTG concentration of 0.8 mM and induction temperature of 25 °C. Compounds A4, A6, A9, A16, and A17 exhibited excellent binding affinity to TeMV VPg, with Kd values of 0.23, 0.034, 0.19, 0.086, and 0.22 µM, respectively. LYS 121 is the key amino acid site. Compounds A9 inhibited the expression of TeMV VPg in Nicotiana benthamiana. The results suggested that TeMV VPg is a potential antiviral target to screen anti-TeMV compounds.

Ethylicin Inhibition of Xanthomonas oryzae pv. oryzicola In Vitro and In Vivo.

Infestation of rice with the bacterium Xanthomonas oryzae pv. oryzicola (Xoc) causes the serious disease bacterial leaf streak (BLS). We studied the effect of ethylicin, a broad-spectrum bactericide, on Xoc both in vivo and in vitro. Ethylicin increases the defensive enzyme activities and defensive genes expression of rice. Ethylicin also significantly inhibited Xoc activity in vitro compared with other commercial bactericides. The half-maximal effective concentration (EC50) of ethylicin was 2.12 µg/mL. It has been shown that ethylicin can inhibit Xoc quorum sensing through the production of extracellular polysaccharides and enzymes, which disrupt the Xoc cell membrane. We used proteomic analysis to identify two oxidative phosphorylation pathway proteins (ACU12_RS13405 and ACU12_RS13355) which affected the virulence of Xoc and validated them using quantitative real-time polymerase chain reaction (qRT-PCR). The results indicate that ethylicin can increase the defense responses of rice and control Xoc proliferation.

Cysteine protease domain of potato virus Y: The potential target for urea derivatives.

The cysteine protease structural domain (CPD) encoded by the potato virus Y (PVY) accessory component protein helper component-proteinase (HC-Pro) is an auxiliary component of aphid virus transmission and plays an important role in virus infection and replication. Urea derivatives have potential antiviral activities. In this study, the PVY HC-Pro C-terminal truncated recombinant protein (residues 307-465) was expressed and purified. The interactions of PVY CPD with urea derivatives HD1-36 were investigated. Microscale thermophoresis experiments showed that HD6, -19, -21 and - 25 had the strongest binding forces to proteins, with Kd values of 2.16, 1.40, 1.97 and 1.12 µM, respectively. An experiment verified the microscale thermophoresis results, and the results were as expected, with Kd values of 6.10, 4.78, 5.32, and 4.52 µM for HD6, -19, -21, and - 25, respectively. Molecular docking studies indicated that the interaction sites between PVY CPD and HD6, -19, -21, and - 25, independently, were aspartic acid 121, asparagine 48, and tyrosine 38, which played important roles in their binding. In vivo experiments verified that HD25 inhibited PVY more than the control agents ningnanmycin and urea. These data have important implications for the design and synthesis of novel urea derivatives.

Platinum-Based Electrocatalysts for Direct Alcohol Fuel Cells: Enhanced Performances toward Alcohol Oxidation Reactions.

In the past few decades, Pt-based electrocatalysts have attracted great interests due to their high catalytic performances toward the direct alcohol fuel cell (DAFC). However, the high cost, poor stability, and the scarcity of Pt have markedly hindered their large-scale utilization in commerce. Therefore, enhancing the activity and durability of Pt-based electrocatalysts, reducing the Pt amount and thus the cost of DAFC have become the keys for their practical applications. In this minireview, we summarized some basic concepts to evaluate the catalytic performances in electrocatalytic alcohol oxidation reaction (AOR) including electrochemical active surface area, activity and stability, the effective approaches for boosting the catalytic AOR performance involving size decrease, structure and morphology modulation, composition effect, catalyst supports, and assistance under other external energies. Furthermore, we also presented the remaining challenges of the Pt-based electrocatalysts to achieve the fabrication of a real DAFC.

Dodecahedral Au/Pt Nanobowls as Robust Plasmonic Electrocatalysts for Methanol Oxidation under Visible-Light Illumination.

Plasmonic nanostructures with large absorption areas under resonant excitation have been utilized extensively in photon-assisted applications. In this work, dodecahedral Au nanobowls were first prepared by an easy and template-free method only through the introduction of H2 PtCl6 and I- during the growth procedure. The Au nanobowls show electron-field enhancement due to the high curvature of the bowl edge, the open region, and dodecahedral morphology. Au/Pt nanobowls, which couple plasmonic Au and catalytic Pt, were then constructed as plasmonic electrocatalysts for methanol oxidation. The mass activity reached 497.6 mA mg-1 under visible-light illumination, which is 1.9 times that measured in the dark. Simultaneously, the electrocatalytic stability is also greatly improved under light excitation. The enhanced properties of the plasmonic Au/Pt electrocatalysts are ascribed to the synergistic effect of the plasmon-enhanced photothermal and hot-carrier effects on the basis of experimental investigations. This work thus offers an effective methodology to construct efficient plasmonic electrocatalysts for fuel cells.

Analysis of amino acid and acyl carnitine profiles in maternal and fetal serum from preeclampsia patients.

Objectives: To analyze and compare concentrations of amino acids (AAs) and acylcarnitine (AC) profiles in maternal-fetal serum from women with preeclampsia (PE) and to assess their use as possible predictors of PE.Methods: This is a retrospective study in which we enrolled a total of 38 pregnant women and their offspring. Pregnant women with PE (n = 14) and healthy pregnant control subjects (n = 24) participated voluntarily in the study. Maternal blood and cord blood were tested using dry blood spot (DBS) specimens, and we detected concentrations of 18 types of AAs and 31 types of AC by using high-performance liquid chromatography tandem mass spectrometry (HPLC-MS), and compared metabolites between the groups. We used logistic regression modeling to estimate the association of each metabolite with development of PE.Results: Concentrations of most AAs and AC in PE mothers were significantly higher than those in the group of control mothers. Cord plasma concentrations of AC in most PE mothers were significantly higher than those in controls; however, in PE, levels of cord plasma concentrations of most AAs were significantly lower, except for Gly, compared with controls. Levels of most AAs and AC were lower in the control and PE groups, with a tendency for lower levels in maternal blood compared to cord blood. Receiver operating characteristics (ROC) and areas under the curves (AUC) analyses using these metabolites did not predict PE individually.Conclusions: Maternal-fetal levels of AAs and AC were associated with PE. But the use of metabolites did not constitute a reliable method for use as a biomarker in the diagnosis of PE. Further prospective studies are needed to clarify the roles of different metabolites involved in the mechanism underlying the development of PE.

Metabolic Engineering of Saccharomyces cerevisiae for De Novo Production of Kaempferol.

Kaempferol is a polyphenolic compound with various reported health benefits and thus harbors considerable potential for food-engineering applications. In this study, a high-yield kaempferol-producing cell factory was constructed by multiple strategies, including gene screening, elimination of the phenylethanol biosynthetic branch, optimizing the core flavonoid synthetic pathway, supplementation of precursor PEP/E4P, and mitochondrial engineering of F3H and FLS. A total of 86 mg/L of kaempferol was achieved in strain YL-4, to date the highest production titer in yeast. Furthermore, a coculture system and supplementation of surfactants were investigated, to relieve the metabolic burden as well as the low solubility/possible transport limitations of flavonoids, respectively. In the coculture system, the whole pathway was divided across two strains, resulting in 50% increased cell growth. Meanwhile, supplementation of Tween 80 in our engineered strains yielded 220 mg/L of naringenin and 200 mg/L of mixed flavonoids-among the highest production titer reported via de novo production in yeast.

AuPt Bipyramid Nanoframes as Multifunctional Platforms for In†Situ Monitoring of the Reduction of Nitrobenzene and Enhanced Electrocatalytic Methanol Oxidation.

Multifunctional metal nanostructures with a hollow feature, especially for nanoframes, are highly attractive owing to their high surface-to-volume ratios. However, pre-grown metal nanocrystals are always involved during the preparation procedure, and a synthetic strategy without the use of a pre-grown template is still a challenge. In this article, a template-free strategy is reported for the preparation of novel AuPt alloy nanoframes through simply mixing HAuCl4 and H2 PtCl6 under mild conditions. The alloy nanostructures show a bipyramid-frame hollow architecture with the existence of only the ten ridges and absence of their side faces. This is the first report of bipyramid-like nanoframes and a template-free method under mild conditions. This configuration merges the plasmonic features of Au and highly active catalytic sites of Pt in a single nanostructure, making it an ideal multifunctional platform for catalyzing and monitoring the catalytic reaction in real time. The superior catalytic activity is demonstrated by using the reduction of nitrobenzene to the corresponding aminobenzene as a model reaction. More importantly, the AuPt nanoframes can track the reduction process on the basis of the SERS signals of the reactants, intermediates, and products, which helps to reveal the reaction mechanism. In addition, the AuPt nanoframes show much higher electrocatalytic properties toward the methanol oxidation reaction than commercial Pt/C electrocatalysts.

Puberty exposure to cigarette smoke extract impairs adult spermatogenesis in the mouse.

Epidemiological studies suggested that exposure to cigarette smoke early in life is associated with long-term health risks. Using a nuclear factor erythroid 2-related factor 2 (Nrf2) knockout (KO) mouse model, we found the sperm concentration and sperm motility were significantly lower in mice exposed to cigarette smoke extract (CSE) beginning at 4 weeks of age compared to 8 week-old mice. Additionally, CSE exposure significantly decreased in vitro fertilization (IVF) and blastocyst rates in the Nrf2 KO mice compared to the wild-type (WT) mice. Exposure to CSE resulted in the highest expression of the antioxidant genes in the CSE-treated WT mice at 8 weeks of age, and it was the lowest in the CSE-treated KO mice at 4 weeks. The study concluded that puberty exposure to CSE significantly affects adult spermatogenesis in agreement with the antioxidant Nrf2 genotype.

Engineering of Hollow PdPt Nanocrystals via Reduction Kinetic Control for Their Superior Electrocatalytic Performances.

Synthesis of hollow metal nanocrystals (NCs) is greatly attractive for their high active surface areas, which gives rise to excellent catalytic activity. Taking PdPt alloy nanostructure as an example, we designed a synthetic tactic for the preparation of hollow metal nanostructures by delicate control over the difference in the reduction kinetic of metal precursors. At a high reduction rate difference, the Pd layer forms from H2PdCl4 and is subsequently etched, leading to the formation of a hollow space. A solid PdPt structure is achieved when the reduction rate of Pd and Pt precursor is comparable. Obviously, the hollow space and composition are tunable as well by adjusting the reduction rate difference. More importantly, the prepared hollow PdPt nanostructures exhibit a branched outer, porous wall, and rough hollow interior. The branched outer and rough hollow interior provide the higher density of unsaturated atoms, whereas the porous wall serves as channels connecting the inner, outer, and reactive agents. Moreover, the periodic self-consistent density function theory suggests that the d-band theory density of state of the PdPt nanoalloys is upshifted in comparison to the monometallic component, which will beneficial for improvement in their catalytic performances. Electrocatalytic tests reveal that the PdPt bimetallic NCs, especially for Pt32Pd68 nanostructures, show excellent catalytic activity and stability toward methanol oxidation reaction owing to their special structures as well as compositions.

Metabolomics analysis of Pseudomonas chlororaphis JK12 algicidal activity under aerobic and micro-aerobic culture condition.

Utilization of algicidal bacteria as a biological agent have been receiving significant interest for controlling harmful algal blooms. While various algicidal bacterial strains have been identified, limited studies have explored the influence of bacterial culture conditions on its algicidal activity. Here, the effect of oxygen on the algicidal activity of a novel bacterium JK12, against a model diatom, Phaeodactylum tricornutum (P. tricornutum) was studied. Strain JK12 showed high algicidal activity against P. tricornutum and was identified as Pseudomonas chlororaphis (P. chlororaphis) by 16S ribosomal RNA gene analysis. JK12 culture supernatant exhibited strong algicidal activity while washed JK12 cells showed no obvious activity, indicating that JK12 indirectly attacks algae by secreting extracellular algicidal metabolites. Micro-aerobic culture condition dramatically enhanced the algicidal activity of JK12 by 50%, compared to that cultured under aerobic condition in 24 h. Extracellular metabolomic profiling of JK12 using gas chromatography-mass spectrometry and liquid chromatography-mass spectrometry analysis revealed significantly higher amounts of allantoic acid, urocanic acid, cytidine 2',3'-cyclic phosphate, uridine 2',3'-cyclic phosphate, and chlorinated tryptophan in the micro-aerobic culture. This is the first report to demonstrate the important role of oxygen on the algicidal activity of a non-pathogenic strain P. chlororaphis. In addition, the metabolomics analysis provided insights into the algicidal mechanism of P. chlororaphis.

Application of the amniotic fluid metabolome to the study of fetal malformations, using Down syndrome as a specific model.

Although monitoring and diagnosis of fetal diseases in utero remains a challenge, metabolomics may provide an additional tool to study the etiology and pathophysiology of fetal diseases at a functional level. In order to explore specific markers of fetal disease, metabolites were analyzed in two separate sets of experiments using amniotic fluid from fetuses with Down syndrome (DS) as a model. Both sets included 10­15 pairs of controls and cases, and amniotic fluid samples were processed separately; metabolomic fingerprinting was then conducted using UPLC­MS. Significantly altered metabolites involved in respective metabolic pathways were compared in the two experimental sets. In addition, significantly altered metabolic pathways were further compared with the genomic characters of the DS fetuses. The data suggested that metabolic profiles varied across different experiments, however alterations in the 4 metabolic pathways of the porphyrin metabolism, bile acid metabolism, hormone metabolism and amino acid metabolism, were validated for the two experimental sets. Significant changes in metabolites of coproporphyrin III, glycocholic acid, taurochenodeoxycholate, taurocholate, hydrocortisone, pregnenolone sulfate, L­histidine, L­arginine, L­glutamate and L­glutamine were further confirmed. Analysis of these metabolic alterations was linked to aberrant gene expression at chromosome 21 of the DS fetus. The decrease in coproporphyrin III in the DS fetus may portend abnormal erythropoiesis, and unbalanced glutamine­glutamate concentration was observed to be closely associated with abnormal brain development in the DS fetus. Therefore, alterations in amniotic fluid metabolites may provide important clues to understanding the etiology of fetal disease and help to develop diagnostic testing for clinical applications.

Facile Growth of High-Yield Gold Nanobipyramids Induced by Chloroplatinic Acid for High Refractive Index Sensing Properties.

Au nanobipyramids (NBPs) have attracted great attention because of their unique localized surface plasmon resonance properties. However, the current growth methods always have low yield or suffer tedious process. Developing new ways to direct synthesis of high-yield Au NBPs using common agents is therefore desirable. Here, we employed chloroplatinic acid as the key shape-directing agent for the first time to grow Au NBPs using a modified seed-mediated method at room temperature. H2PtCl6 was added both during the seed preparation and in growth solution. Metallic Pt, reduced from chloroplatinic acid, will deposit on the surface of the seed nanoparticles and the Au nanocrystals and thus plays a critical role for the formation of Au NBPs. Additionally, the reductant, precursor, and surfactant are all cheap and commonly used. Furthermore, the Au NBPs offer narrow size distribution, two sharp tips, and a shared basis. Au NBPs therefore show much higher refractive index sensitivities than that of the Au nanorods. The refractive index sensitivities and lager figure of merit values of Au NBPs exhibit an increase of 63% and 321% respectively compared to the corresponding values of Au nanorod sample.

Simultaneous tunable structure and composition of PtAg alloyed nanocrystals as superior catalysts.

PtAg alloyed nanostructural catalysts were firstly prepared by co-reduction of AgNO3 and H2PtCl6 precursors in growth solution using a seed-mediated method. By simply changing the molar ratio of the metal precursors, the morphologies of the porous alloyed nanocrystals can be tuned from multipetals to multioctahedra. Simultaneously, the alloy composition can be varied from Pt76Ag24 to Pt66Ag34. The catalytic properties of the prepared PtAg alloyed nanocrystals with a tunable structure and composition were tentatively examined by choosing the reduction of 4-nitrophenol with NaBH4. The reaction rate normalized to the concentration of catalysts was calculated to be 318.9 s(-1) mol(-1) L and 277.4 s(-1) mol(-1) L for Pt70Ag30 and Pt66Ag34 porous catalysts, which is much higher than the pure Pt catalysts. Moreover, PtAg nanostructures can also serve as efficient electrocatalysts toward the methanol oxidation reaction, especially for Pt70Ag30 and Pt66Ag34 porous nanocrystals. The electrocatalytic activity and the durability were both highly enhanced compared to the commercial Pt/C catalyst. In addition, we also investigated the enhancement mechanism.

Ultrasound assisted extraction of carbohydrates from microalgae as feedstock for yeast fermentation.

Recently, carbohydrates biomass from microalgae is considered as a promising and inexpensive feedstock for biofeuls production by microorganism fermentation. The main obstacle of the process is microalgae pretreatment and carbohydrates extraction from algal cell. In this study, comparison of three pretreatment methods was performed and the results showed that ultrasonic assisted extraction (UAE) was very effective. The effects of four parameters (ultrasonic power, extraction time, flow rate and algal cell concentration, respectively) on extraction efficiency were also investigated. Additionally, in order to identify significant factors for glucose yield, combination of these four parameters was examined by using fractional factorial design (FFD) and the regression model was obtained. Meanwhile, the refined model was confirmed as a good fitting model via analysis of variance (ANOVA). After extraction, glucose obtained from microalgae was used as substrate for Rhodosporidium toruloides fermentation and yeast biomass was much higher than that of control culture.

The effect of different trophic modes on lipid accumulation of Scenedesmus quadricauda.

In this study, the effects of different carbon sources on cell growth and lipid accumulation of Scenedesmus quadricauda were investigated. Results showed that S. quadricauda could grow on photoautotrophic, heterotrophic and mixotrophic modes. The lipid yield of S. quadricauda was much lower in the culture containing NaHCO(3) as only carbon source, while CO(2) and glucose concentration significantly influenced cell yield and lipid accumulation in photoautotrophic and heterotrophic culture, respectively. Furthermore, lipid content of S. quadricauda in mixotrophic culture (33.1% of cell dry weight) was much higher than that in photoautotrophic and heterotrophic cultivation (14-28%). Therefore, upon comparing these three trophic modes, present results revealed mixotrophy was the optimal culture method for S. quadricauda to produce lipid. Besides, it was a feasible and promising strategy to culture S. quadricauda using starch wastewater as raw material, which could reduce chemical oxygen demand (COD) of wastewater and the cost of biodiesel production.