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The probable nanotoxicity to human health and the environment is a significant challenge for the sustainable application of nanomaterials in medicine. The cytototoxical effect of succimer (meso-2,3-dimercaptosuccinic acid-DMSA) coated titanium dioxide (DMSA-TiO2) with cultured human aortic endothelial cells (HAoECs) was assessed in this investigation. Our findings have shown that DMSA-TiO2 can be accumulated in HAoECs and dispersed in a cytoplasm on the culture medium. DMSA-cytotoxicity TiO2 effects were dose-responsive, and the concentrations were of little toxicity, and MTT stain testing showed that they had only 0.02 mg ml−1. Meanwhile, the lactate dehydrogenase biomarker was not considerably more remarkable than the biomarker from untreated (control) cells (free DMSA-TiO2). Though, also without any apparent signs of cell damage, the endocrine functions for prostacyclin I-2 and endothelin-1 and the urea transporter functions were modified. In addition, in vitro endothelial tube development has been shown that HAoECs could induce angiogenesis even with small amounts of DMSA-TiO2 (0.01 and 0.02 mg ml−1). Further, we have examined the in vivo toxicity and biochemical parameter by animal model. Furthermore, in vivo assessments designated that the resulting DMSA-TiO2 presented synergistic activities of angiogenesis activity. Overall, these findings show the cytotoxicity of DMSA-TiO2 and could induce adverse effects on normal endothelial cells.

To investigate the biomarker(s) that could affect the decision for immediate or delayed delivery in severe preeclampsia.Data on serum levels of alanine aminotransferase (ALT), aspartate aminotransferase (AST), alkaline phosphatase (ALP), creatinine, blood urea nitrogen (BUN), uric acid (UA) and platelet counts from 134 cases were collected and analysed.Higher UA levels were seen in case with immediate delivery. Higher stillbirth was seen in cases with delayed delivery.UA levels could be a potential management biomarker for immediate or delayed delivery in severe preeclampsia. However, the higher risk of stillbirth must be considered in delayed delivery.

Azobenzene compounds have been widely used in many fields and through their response to light they can be used to regulate the properties of ordered structures. In this paper, sub-micrometer colloidal SiO2 spheres are prepared and azobenzene groups are grafted on the surface of SiO2 microspheres. The SiO2 microspheres grafted with azobenzene groups could self-assemble to form photosensitive photonic crystals (PCs), whose photonic bandgaps red-shifted as irradiated by UV light and showed good reversibility.

Thermoresponsive thiol-terminated poly(N-isopropylacrylamide) (PNIPAM) and diblock poly(ethylene glycol)-b-poly(N-isopropylacrylamide) (PEG-b-PNIPAM) were synthesized through reversible addition-fragmentation chain transfer (RAFT) polymerization and aminolysis reaction. The lower critical solution temperature (LCST) of the polymers increases with the increase of PEG chain segment. Such polymers were used to modify gold nanoparticles (AuNPs) by Au–S bonds. The optical limiting property of the polymer-stabilized gold nanoparticles was investigated, and the results show that the thermoresponsive polymer-stabilized gold nanoparticles exhibit enhanced optical limiting effect relative to pristine AuNPs. The higher optical limiting energy threshold was observed for gold nanoparticles stabilized with polymers having higher LCST.

Simple Summary Some studies have confirmed the variation in milk profiles when dairy cows show estrus. However, only a few milk components, such as fat, protein, and lactose, have been investigated so far, and thus any changes in the many other parts of milk’s composition due to estrus are unknown. Milk mid-infrared (MIR) spectra consist of wavenumbers, which provide insight into the chemical composition of milk. The MIR spectrum reflects the global composition of milk, but this information is currently underused. In this study, we considered MIR wavenumbers as traits, and directly studied the spectral information as a way to study the estrus of dairy cows linked to milk composition. This research provides a deeper understanding of the milk MIR spectrum and may lead to new approaches for estrus detection in dairy cows from routine milk analysis, thereby guiding an opportune insemination time. Abstract Milk produced by dairy cows is a complex combination of many components. However, at present, changes in only a few milk components (e.g., fat, protein, and lactose) during the estrus cycle in dairy cows have been documented. Mid-infrared (MIR) spectroscopy is a worldwide method routinely used for milk analysis, as MIR spectra reflect the global composition of milk. Therefore, this study aimed to investigate the changes in milk MIR spectra and milk production traits (fat, protein, lactose, urea, total solids (TS), and solid not fat (SnF)) due to estrus. Cows that were successfully inseminated, leading to conception, were included. Cows confirmed to be pregnant were considered to be in estrus at the day of insemination (day 0). A general linear mixed model, which included the random effect of cows, the fixed classification effects of parity number, days in relation to estrus, as well as the interaction between parity number and days in relation to estrus, was applied to investigate the changes in milk production traits and 1060 milk infrared wavenumbers, ranging from 925 to 5011 cm−1, of 371 records from 162 Holstein cows on the days before (day −3, day −2, and day −1) and on the day of estrus (day 0). The days in relation to estrus had a significant effect on fat, protein, urea, TS, and SnF, whose contents increased from day −3 to day 0. Lactose did not seem to be significantly influenced by the occurrence of estrus. The days in relation to estrus had significant effects on the majority of the wavenumbers. Besides, we found that some of the wavenumbers in the water absorption regions were significantly changed on the days before and on the day of estrus. This suggests that these wavenumbers may contain useful information. In conclusion, the changes in the milk composition due to estrus can be observed through the analysis of the milk MIR spectrum. Further analyses are warranted to more deeply explore the potential use of milk MIR spectra in the detection of estrus.

Thermosensitive and photosensitive polymers (PNIPAM-Azo) were synthesized by thiol-ene click reaction with PNIPAM with terminal thiol groups (PNIPAM-SH) and azobenzene compounds containing a double bond. Different catalysts were used in the reaction to investigate their catalytic effect and a photocatalyst was found to have the best effect. The aggregation behavior of PNIPAM-Azo in aqueous solution was studied, which showed that PNIPAM-Azo had good surface activity in aqueous solution, and could form different aggregates at different concentration. Meanwhile PNIPAM-Azo exhibited good light response and thermal response, only the LCST of PNIPAM-Azo increased a little after long time ultraviolet irradiation.

The aim of the present study was to identify the stage during acid etching of dental enamel where scratches introduced by sectioning and grinding procedures were eliminated. Nitric acid was used as etchant. Four hundred 2-3 mm-thick longitudinal sections of human third molar crowns were assigned to 80 groups, each group differing with respect to grinding procedure (silicon carbide paper grit 600; 1,000; 1,200; and 1,200 + polishing), acid concentration (0.1%, 1%, 2.5%, and 5%) and etching time (15, 30, 45, 90, and 180 s). Observation of the specimens with scanning electron microscopy (SEM) showed that elimination of scratches was facilitated by increasing fineness of grinding paper and polishing, and by increasing acid concentration and increasing etching time. An acid concentration of 0.1% did not remove scratches totally irrespective of grinding procedure or etching time, 1% acid removed most scratches after 45-90 s, while 2.5% and 5% acids removed most scratches after 30-45 s. It is proposed that the scratches are eliminated/obscured through a combined effect of the acid and the inherent structure of the enamel. The results of the present study may serve as a guide in choosing the best procedures for obtaining scratch-free enamel surfaces through acid etching with the least possible loss of enamel substance. Research highlights Sectioning and grinding produce scratches in dental enamel. Scratches are eliminated by acid etching prior to SEM studies of enamel structure. Scratch elimination increases with increasing acid strength and etching time and is facilitated by finer grit grinding paper and polishing.

The citrate-reduction method is extensively used to prepare gold colloids particularly in the application of biological and medical areas. Tartrate as a substitute of citrate was first employed to prepare gold colloids from chloroauric acid due to its similar chemical structures to citrate. The size of obtained monodisperse quasi-spherical gold nanoparticles was adjusted from 27 nm to 40 nm when changing the molar ratio of sodium tartrate to chloroauric acid, while the particle size only changed from 54 to 62 nm under different molar ratio of tartaric acid to aurate. The nanoparticle size is mainly determined by the pH of reaction media in nucleation and the stabilizer concentration in the coagulation of initial nuclei for the nanoparticle growth. The majority of obtained gold nanoparticles have polycrystalline structure. This method should be important for direct one-pot preparation of gold colloids with sizes of around 30–60 nm.

The impurity of unpurified carbon quantum dots (CQDs) severely limits their application. In this paper, CQDs synthesized by ultrafast microwave hydrothermal method from L -cystine were purified by both dialysis and direct phase-transfer. The as-obtained CQDs in basic aqueous reaction mixture show excitation-independent fluorescence around 505 nm with a maximum excitation at 421 nm and pH-responsive emission intensity. However, after purification by dialysis the CQDs display excitation-dependent blue fluorescence from 410 to 500 nm with respect to the excitation from 310 to 430 nm. Particularly, the CQDs purified by direct phase-transfer into various organic solvents show two strong blue fluorescence peaks respectively focusing on 422–434 nm and 400–410 nm with a maximum excitation at 370–372 nm. The quantum yield of the CQDs decreases to 45.1% after a purification by dialysis from the original 82.7%, while it decreases to 57.5% after a purification of phase-transfer. The CQDs extracted in organic solvents are demonstrated to be pure small crystalline-carbon nanoparticles with chemically surface-grafted groups, while the dialyzed CQDs will physically adsorb additional L -cystine, sodium and by-product nitrate ions. The difference of surface state and solvent environment of these CQDs shall contribute to the different fluorescence property. Such strong luminescent, pure CQDs in organic solvents should have obvious advantages in further applications.

To exploit the application potential of Ag nanoparticles (AgNPs) in optical limiting materials, it is significant to develop AgNPs doped polymeric hybrid materials. In this paper, spherical AgNPs were prepared using the seeding growth method. An additional silica coating was employed to obtain the Ag@SiO 2 core-shell materials. Then Ag@SiO 2 was doped into polydimethylsiloxane(PDMS) rubbers to investigate their optical limiting property to laser at 532 nm. The results showed that the Ag@SiO 2 doped PDMS rubber exhibited good optical limiting effect, which should be attributed to the nonlinear optical absorption and refraction. The AgNPs-PDMS hybrid materials would be very promising in optical limiting application area.

When gold nanoparticles (AuNPs) are blended with matrix polymers for material engineering of a nanoparticle doped polymer matrix, one frequently observes nanoparticles’ aggregation due to their large interface energy. In this work, poly(dimethyl siloxane)-capped AuNPs (AuNP@PDMS) were successfully synthesized via hydrosilylation from alkenyl-terminated AuNPs and hydride-terminated PDMS polymer. The AuNP@PDMS particles have a well dispersed state after blending with polysiloxane elastomer prepolymer because the same component of the shell polymer to matrix polymer should decrease maximumly the interface influence between the nanoparticles and the polymer matrix. Therefore, uniform AuNP-doped silicone elastomer material with brilliant red color was obtained after vulcanization. The average molar absorption coefficient of doped AuNPs in silicone elastomer was deduced to be 3.06 × 10 7 cm −1 mol −1 . Such AuNP-doped silicone elastomer showed good thermostability and obvious optical limiting performance. The intrinsic homogeneity of shell polymer on nanoparticles and matrix polymer is a remarkable advantage to diminish the interface influence in blending of nanoparticles with polymer matrix, thus could provide uniform nanoparticle-doped polymeric materials.

Functional long-chain alkyl disulfides were herein synthesized under liquid-liquid phase-transfer catalysis. The component of final products could be mainly controlled by feeding molar ratio of S/Na 2 S which factually dominated a chemical equilibrium among monosulfide, disulfide and trisulfide anions. The binding capability of sulfur anions with dimethyldidodecylammonium cation increases in the order of monosulfide

The study aimed at finding an optimal combination of acid concentration and etching time when nitric acid is used as etchant for the study of the finer details of human dental enamel structure. Four hundred 2-3-mm-thick segments of facio-lingually sectioned human third molar crowns were assigned to 20 groups with 20 specimens in each group, each group differing with respect to acid concentration (0.1, 1, 2.5, and 5%) and etching time (15, 30, 45, 90, and 180 s). After etching and preparation, specimens were observed in the scanning electron microscope (SEM). Surface roughness/topography increased with increasing acid concentration and increasing etching time, but not in a linear fashion; generally, prisms tended to go from flat-surfaced to cone-shaped and prism sheaths from fissure-like to wedge-shaped. Intragroup variations and intergroup similarities were considerable. The two major enamel factors determining the etch effect are crystal orientation and prism sheath properties. Other factors, such as distribution of porosities and crystal quality, also contribute probably. Slight to moderate topography is best for observing the finer enamel structure, for example, etching with concentrations in the range 0.1-1% and with etching times in the range 15-90 s, the stronger the acid, the shorter the time. The depth effect of nitric acid is judged to be relatively small. Considerable variations in expression of prism cross-striations were observed. SEM observations of acid-etched enamel in carefully selected planes are a powerful method for the study of enamel structure, bearing in mind the artifactual aspects of the observed surface.

Due to the potential application of gold nanorods (GNRs) in tunable optical limiting materials, it is significant to develop GNRs/polymer hybrid materials. In this paper, GNRs were prepared using a seed-mediated growth method and coated with silica shells through hydrolysis of tetraethoxysilane under alkaline condition. The silica coated GNRs were then introduced into room-temperature vulcanized silicone rubber. Optical limiting property of the GNRs/silicone nanocomposites was investigated. The results indicated the GNRs doped silicone rubber sheets possessed good optical limiting performance and the optical limiting behavior was mainly attributed to the nonlinear absorption. The GNRs doped silicone materials would be good candidates for practical optical limiting applications.

Porous coral-like Pd/C3N4-C nanocomposites are fabricated by a simple one-pot chemical reduction method. Their electrocatalytic performance is ~50% higher than a carbon-loaded palladium electrocatalyst (Pd/C) in alkaline media. This confirms that the glucose electrooxidation and sensing performance of a Pd/C can be improved by the synergy of graphitic carbon nitride (C3N4), though C3N4 exhibits poor electrical conductivity. Compared to Pd/C, the size of Pd nanoparticles in Pd/C3N4-C decreases. As a result, the activity of Pd/C3N4-C is enhanced due to the higher dispersion and the synergistic effect. Pd/C3N4-C presents a rapid response and high sensitivity to glucose. The sensitivity for glucose sensing at Pd/C3N4-C is 3.3 times that of at Pd/C in the range of 0.001&ndash, 10 mM. In the lower range of 0.001&ndash, 1 mM, the sensitivity at Pd/C3N4-C is ~10 times greater than Pd/C.

Silica-coated metal nanoparticles are increasingly important for their many promising applications. A facile one-step synthesis of noble metal@silica core–shell nanospheres is necessary for their application in laser protection field. In this letter, a one-pot fabrication of silver@silica nanospheres was carried out, and then, silver nanoparticle-doped silicone rubber hybrid materials were prepared. Their optical limiting property to nanosecond laser was investigated and comparable optical limiting property with similar material involving multi-step synthesis of silica-coated metal nanoparticles was found.

As a kind of new optical limiting materials, gold nanoparticles have optical limiting property owing to their optical nonlinearities induced by surface plasmon resonance (SPR). Gold nanorods (GNRs) possess transversal SPR absorption and tunable longitudinal SPR absorption in the visible and near-infrared region, so they can be used as potential optical limiting materials against tunable laser pulses. In this letter, GNRs were prepared using seed-mediated growth method and surface-modified by silica coating to obtain good dispersion in polydimethylsiloxane prepolymers. Then the silicone rubber films doped with GNRs were prepared after vulcanization, whose optical limiting property and optical nonlinearity were investigated. The silicone rubber samples doped with more GNRs were found to exhibit better optical limiting performance.

Alpha-linolenic acid (ALA) is known for its ability to promote the production of β-carotene in Blakeslea trispora. However, the mechanism is still poorly understood. In this study, gas chromatography-mass spectrometry (GC-MS)-based metabolomic approach and multivariate analysis were used to study mechanisms underlying the regulation effects of ALA on β-carotene synthesis in B. trispora. ALA treatment promoted the biomass of B. trispora and β-carotene production. The maximum β-carotene production 5.344 mg L−1 was realized after 72 h of cultivation in the presence of 50 μL ALA. The intracellular metabolite profiles found upon treatment of the cells with different addition time points of ALA were unique and could be distinguished from the aid of principal component analysis (PCA). Furthermore, partial least-squares-discriminant analysis (PLS-DA) revealed a group classification and pairwise discrimination between the control and ALA treated groups, and 28 differential metabolites with variable importance in the projection (VIP) value greater than 1. The addition of ALA decreased the glycolysis, TCA cycle and fatty acid synthesis. The accumulation of linolenic acid and linoleic acid indicated that ALA was directly absorbed by the fungus and transformed into its own linolenic acid. As a result, the flux from acetyl-CoA to β-carotene synthesis increased. Besides, the addition of ALA increased the level of dissolved oxygen and the production of β-carotene.

Core-shell AuNR@Ag nanostructures were synthesized and surface-grafted with thermosensitive poly(N-isopropylacrylamide) to enhance stability and endow stimuli-responsive property. The AuNR cores showed average dimensions of 8-nm diameter and 33-nm length, while the anisotropic silver shells displayed 1–2 nm thin side and maximal 8 nm fat side. The obtained polymer-stabilized AuNR@Ag nanostructures as catalysts showed normal Arrhenius change of apparent rate constant, k app, in catalyzed reaction between 20 and 30 °C, but displayed a decrease of k app with respect to the temperature increasing between 32.5–40 °C, showing self-inhibition of the observed catalytic activity. Such “smart” self-inhibition of catalytic activity at enhanced temperature can be attributed to the thermosensitive response of the grafted polymer molecules and should be significant to control the reaction rate and avoid superheat for exothermic reactions. Such polymer-stabilized nanocatalyst also could be recovered and reused in the catalytic system.

Optical limiters against femtosecond laser are essential for eye and sensor protection in optical processing system with femtosecond laser as light source. Anisotropic Ag nanoparticles are expected to develop into optical limiting materials for femtosecond laser pulses. Herein, silver nanoprisms are prepared and coated by silica layer, which are then doped into silicone rubber to obtain hybrid rubber sheets. The silver nanoprisms/silicone hybrid rubber sheets exhibit good optical limiting property to femtosecond laser mainly due to nonlinear optical absorption.

Dendritic amphiphiles as novel building blocks are very important for self-assembling in the supramolecular chemistry area. In this work, a carbosilane dendrimer with hexamethylene as the branching unit (G1) was first synthesized as a hydrophobic core and then linked with poly(ethylene glycol) (PEG) units as the periphery by a hydrosilylation reaction to prepare an amphiphilic dendrimer (G1-PEG) with a yield of 27%. The aggregation behavior of G1-PEG in water was studied with surface tension, dynamic light scattering and transmission electron microscopy methods. The surface tension data showed that the critical aggregation concentration of such dendrimers in water is approximately 0.75 g L−1. The results of dynamic light scattering and transmission electron microscopy indicated that the aggregate size of G1-PEG dendrimers in water is related to the concentration. Small micelles of about 10 nm were found at high concentration, large vesicles of about 100 nm were observed at low concentration, and a mixture of micelles and vesicles was found at middle concentrations. The encapsulation of G1-PEG to a fluorescence probe verified the existence of a hydrophobic microenvironment in the aggregates at high concentrations of the amphiphilic dendrimer. © 2014 Society of Chemical Industry

Using native signal peptide, an alkaliphilic actinomycete xylanase XynK was overexpressed in Escherichia coli and secreted into the culture medium completely. At its optimum catalytic temperature of 55 °C, the cellulose-free xylanase exhibits high activity and stability at pH 7.0-11.0. In comparison with the well-studied actinomycete xylanase from Streptomyces lividans, as an alkaliphilic xylanase, XynK exhibited different biochemical and catalytic characteristics. With the aid of site-directed mutagenesis, some residues were demonstrated to be important to the activity, stability, or substrate binding of the enzyme. The pH stability of mutants H131S and W135A both decreased obviously under high pH values. Combined with their K(m) parameters and homology model analysis, His131 was proposed to be important to both substrate binding and enzyme catalyzing, whereas Trp135 significantly influenced enzyme stability. Good stability under alkaline condition, as well as high secretory expression implies good potentials of the alkaline xylanase in various industrial applications. In addition, results from site-directed mutagenesis provide useful information for further pH stability mechanisms investigation.

The present review focuses on core-shell nanostructures of spherical gold nanoparticles (Au NPs) and biocompatible polymers mainly from the view points of preparation approaches, nanocomposite properties and potential applications for biology. The preparation approaches are assorted into direct-reduction, covalent "graft-to", "graft-from" approach, surface bonding and physical adsorption. Various biocompatible polymers are involved such as the thermosensitive polymers, pH-responsive polymers, antibiofouling polymers, conductive polymers and several natural polymers. The encapsulating and loading properties, cellular uptake and drug release control, as well as biorecognition, targeting and sensing potential are discussed in connection with biological systems. These polymeric gold nanocomposites will have a great potential in biotechnology and life science but also face enormous challenge in future applications.

Introduction Preeclampsia is a pregnancy specific disorder and currently the only effective treatment is delivery of placenta. To control maternal and fetal complications, immediate delivery is well recommended, although studies have suggested that expectant management is possible for both severe and mild preeclampsia. A recent study also suggested that the most trigger for delivery in preeclampsia was difficult to control blood pressure. The indications for delivery within or after 48hours were largely dependent on obstetricians’ experiences. Objectives In this study we investigated whether there is any biomarker(s) or clinical parameter(s) that may affect the decision for either immediate delivery or expectant management. Methods Data from157 women with preeclampsia were collected from a referral university teaching hospital and data included clinical parameters and laboratory biomarkers. A retrospective analysis was performed. Results There were 122 cases (77%) who delivered within 48 hours because of either maternal or fetal conditions. Of 157 cases, 110 cases (70%) were early onset preeclampsia. In early onset preeclampsia, 79 cases (72%) delivered within 48 hours. There was no difference in clinical parameters between cases who delivered within 48 hours and who did not. There were no differences in ALT or ASL or ALP or Uric acid or Blood urea nitogen or creatinine or cystatin C or platelet counts between cases who delivered within 48 hours and who did not. In late onset preeclampsia (n = 47), 43 cases (91%) delivered within 48 hours. There were also no differences in both clinical parameters and liver or renal biomarkers between cases who delivered within 48 hours and who did not. Similar findings were also observed in severe and mild preeclampsia. Conclusions Our study demonstrated that there is currently no biomarker(s) for predicting immediate delivery or expectant management. These results were regardless of the severity or the time of onset of preeclampsia.

The potential use of arachidonic acid (AA) to enhance the production of β-carotene in Blakeslea trispora was investigated in this work. To study the mechanism of the B. trispora response to AA, we used a systematic analytical approach to investigate the changes in the B. trispora cell metabolome at different time points after AA treatment. A maximum of β-carotene production was obtained when 0.4g/l AA was added after 36h of cultivation. Gas chromatography-mass spectrometry (GC-MS)-based metabolomics approach and a multivariate analysis were used to investigate the intracellular biochemical changes in B. trispora. With the aid of principal component analysis (PCA), the intracellular metabolite profiles of all the groups were distinguished. Moreover, a group classification and pairwise discrimination between the control and AA-treated groups were obtained through partial least-squares-discriminant analysis (PLS-DA), and 27 differential metabolites with variable importance in the projection (VIP) value higher than 1 were identified, which was also confirmed by the subsequent hierarchical cluster analysis (HCA). Separation of the control and AA-treated groups was mainly due to the compounds of the Krebs cycle, fatty acids and amino acids. With the treatment of AA, the glycolysis was enhanced and the use of glucose for fermentation was increased. The increased levels of some fatty acids and decreased levels of amino acids in the AA-treated cells could also be the responses to the addition of AA. Metabolomics provided a powerful methodology to gain insight in metabolic changes induced by metabolic stimulators in microorganisms.

Model organisms play critical roles in life science. At present, lack of mature model systems is one of the major bottlenecks that hinder the study of the biosynthesis of natural medicines. Ganoderma lucidum is one of the most widely studied medicinal organisms and has the general features of model organisms: short life cycle, ability to produce large number of progenies, small genome size, easy to culture and genetically transform, and no harm for human being and the environment. In addition, G. lucidum involves multiple biosynthetic pathways of secondary metabolites, making it an ideal model to study the biosynthesis of secondary metabolites and their regulations. Recently, the elucidation of the chromosome-level genome has laid the solid foundation for further application of G. lucidum as a medicinal model organism. G. lucidum is supposed to play important roles in the study on the diversity of secondary metabolites, development of medicinal fungi and synthetic biology of natural medicines. In addition, the proposal of G. lucidum as a medicinal model fungus will greatly contribute to introducing state-of-the-art technologies and strategies of modern life sciences into the study of medicinal organisms and uncovering the common mechanisms and principles in the biosynthesis of secondary metabolites, thus paving the way for the construction of effective and controllable biosynthetic platform of natural medicines.

The enzyme 6-phospho-β-glucosidase is an important member of the glycoside hydrolase family 1 (GH1). However, its catalytic mechanisms, especially the key residues determining substrate specificity and affinity, are poorly understood. A metagenome-derived gene sequence, encoding a novel 6-phospho-β-glucosidase designated Pbgl25-217, was isolated and characterized. The optimal conditions for enzymatic activity were 37�C and pH 7; Ca 2+ , Mg 2+ , and Mn 2+ stabilized the activity of Pbgl25-217, whereas Ni 2+ , Fe 2+ , Zn 2+ , Cu 2+ , and Fe 3+ inhibited its activity. The K m and V max of Pbgl25-217 were 4.8 mM and 1,987.0 U mg −1 , respectively. Seven conserved residues were recognized by multiple alignments and were tested by site-directed mutagenesis for their functions in substrate recognition and catalytic reaction. The results suggest that residues S427, Lys435, and Tyr437 act as “gatekeepers” in a phosphate-binding loop and play important roles in phosphate recognition. This functional identification may provide insights into the specificity of 6-phospho-β-glycosidases in GH1 and be useful for designing further directed evolution.

Na(+)/H(+) antiporters play important roles in ion and pH homeostasis. In this study, two NhaD homologues that effectively catalyze Na(+)/H(+) antiporter were identified from Halomonas sp. Y2, a halotolerant and alkaliphilic strain isolated from sodium enriched black liquor. They exhibited high sequence identity of 72 % and similar binding affinities for Na(+) and Li(+) translocation, while having different pH profiles. Ha-NhaD1 was active at pH 6.0 and most active at pH 8.0-8.5, whereas Ha-NhaD2 lacked activity at pH 6.0 but exhibited maximum activity at pH 9.5 or higher. Based on multiple alignments, 11 partially conserved residues were selected and corresponding mutants were generated for Ha-NhaD1. As expected, replacement of most of the hydrophobic residues abolished the cation exchange activities. Three serine residues at positions 200, 282 and 353 in Ha-NhaD1 were replaceable by alanines with partial retention of activity. The S353A mutant exhibited significantly reduced binding affinity for Na(+) and Li(+), while S282 mutant exhibited an alkaline shift of about 1.5 pH units, as compared to the wild type Ha-NhaD1. Serine at position 282 was predicted to be located in transmembrane segment VIII and was found to be important in regulating pH sensitivity in concert with flanking residues.

The nanoparticle dispersity and interfacial property could be considered as a basis of their further application in the nanostructured materials. In this paper, the dispersity and interfacial phenomena of poly(N-isopropylacrylamide) modified gold nanoparticles were investigated. Firstly, such polymer/gold nanocomposites were demonstrated to have a good dispersity in water, tetrahydrofuran, alcohols and also chloroform, so they were used to entrap fluorescent dye-labelled lipids in chloroform as nanocontainers and subsequently delivery the fluorescent lipids into water as nanocarriers. Secondly, when the nanocomposites in water/chloroform mixture were heated above 35 degrees C, the nanocomposite particles could be partially transferred from water into chloroform across the interface, and they would come back into water again as cooling, displaying a reversible thermal response. Moreover, such polymer/gold nanocomposites at the immiscible water/toluene fluids preferred to assembly into 2-dimensional membranes with variable density at the water/oil interface. The special dispersion properties of the poly(N-isopropylacrylamide)/gold nanocomposites provide many potentials in the future.

Polymeric nanovesicles self-assembled by amphiphilic block copolymers have attracted much attention in the biodelivery of hydrophobic drugs. In this paper, the amphiphilic copolymers of poly(dimethylsiloxane)-block-poly(ethylene glycol) (PDMS-b-PEG) were synthesized to fabricate polymeric nanovesicles in mixed solvent of THF and water. Dynamic light scattering (DLS) were used to monitor the assembling process of the block copolymers, and the aqueous nanovesicle solution could be obtained by a slow evaporation of THF. The vesicle size could be adjusted according to the volume ratio of water to THF and also the concentration of copolymers in the assembly. Higher water content in the mixed solvent produced smaller vesicles, while higher polymer concentration caused the formation of larger vesicles. The hydrophobic domain of the obtained nanovesicles could encapsulate hydrophobic drugs based on the hydrophobic interaction, in which the nanovesicles acted as water-soluble hydrophobic nanotanks. The drug encapsulation capability of these nanovesicles might exhibit a significant potential as drug nanocarriers in biodelivery system.

Heavy-metal pollution of crops seriously affects food safety and human health in China. The purpose of this study is to estimate the concentrations of heavy metals economically and accurately using spectroscopy. The spectral data of winter wheat canopy at 61 sampling points were collected in Longkou City, and the concentration of Pb, Zn, Cd, Cr, Ni, and Hg was measured. Eight estimation models were established based on the back-propagation neural network (BPNN), the partial least squares regression, and the stepwise multiple linear regression methods combined with reflectance spectra, first-order derivative of spectral reflectance (FDR), second-order derivative of spectral reflectance, and spectral parameters (SPs). Spatial interpolation was used to map the heavy-metal concentration. The results showed that the best model for Pb, Zn, and Cd was the BPNN model with SPs, for Cr, Ni, and Hg was the BPNN model with FDR. The concentration of Hg was lower in the northwest, Pb and Zn were higher in the middle and south, Cd was lower in the middle and west, and Cr and Ni were higher in the southeast. This study will provide effective technical support for the economical and accurate monitoring of heavy metals.

The influence of yttrium on the corrosion residual strength of an AZ91D magnesium alloy was investigated detailedly. Scanning electron microscope was employed to analyze the microstructure and the fractography of the studied alloys. The microstructure of AZ91D magnesium alloy is remarkably refined due to the addition of yttrium. The electrochemical potentiodynamic polarization curve of the studied alloy was performed with a CHI 660b electrochemical station in the three-electrode system. The result reveals that yttrium significantly promotes the overall corrosion resistance of AZ91D magnesium alloy by suppressing the cathodic reaction in corrosion process. However, the nucleation and propagation of corrosion pits on the surface of the 1.0 wt.% Y modified AZ91D magnesium alloy indicate that pitting corrosion still emerges after the addition of yttrium. Furthermore, stress concentration caused by corrosion pits should be responsible for the drop of corrosion residual strength although the addition of yttrium remarkably weakens the effect of stress concentration at the tip of corrosion pits in loading process.

In this study, the adsorption and desorption properties of sulforaphane on macroporous resins (HP20, SP207, SP850, and HP2MGL) were investigated. Analysis revealed that SP850 resin was most effective in the separation of sulforaphane. The equilibrium experimental data obtained at different temperatures were well fitted to the Langmuir and Freundlich isotherms. To optimize the separation process, dynamic adsorption and desorption tests were performed with a column packed with SP850 resin. The results showed that the optimum parameters for adsorption were as follows: flow rate: 5 BV/h, pH 2, temperature: 25°C; for desorption: ethanol–water (40:60, v/v), 6 BV as an eluent, flow rate: 6 BV/h. The highest purity of sulforaphane product was 85.9%, i.e., 107‐fold higher than those in broccoli seeds through one run treatment on the column packed with SP850 resin under normal conditions. This indicated the high efficiency of SP850 resin in separating sulforaphane.

Targeted nanobubbles have been reported to improve the contrast effect of ultrasound imaging due to the enhanced permeation and retention effects at tumor vascular leaks. In this work, the contrast enhancement abilities and the tumor targeting potential of a self-made VEGFR2-targeted nanobubble ultrasound contrast agent was evaluated in - vitro and in-vivo . Size distribution and zeta potential were assessed. Then the contrast-enhanced ultrasound imaging of the VEGFR2 targeted nanobubbles were evaluated with a custom-made experimental apparatus and in normal Wistar rats. Finally, the in-vivo tumor-targeting ability was evaluated on nude mice with subcutaneous tumor. The results showed that the target nanobubbles had uniform distribution with the average diameter of 208.1 nm, polydispersity index (PDI) of 0.411, and zeta potential of -13.21 mV. Significant contrast enhancement was observed in both in-vitro and in-vivo ultrasound imaging, demonstrating that the self-made target nanobubbles can enhance the contrast effect of ultrasound imaging efficiently. Targeted tumor imaging showed less promising result, due to the fact that the targeted nanobubbles arriving and permeating through tumor vessels were not many enough to produce significant enhancement. Future work will focus on exploring new imaging algorithm which is sensitive to targeted nanobubbles, so as to correctly detect the contrast agent, particularly at a low bubble concentration.

Amino-terminated carbosilane dendrimer-platinum complex was synthesized and their crystal and morphology were investigated with transmission electronic microscopy (TEM) and scanning electronic microscopy (SEM). Mono-dispersed complex molecule in DMSO solvent showed a size of about 3 nm. Microcrystal flake of the complex was found with a lattice of hexagonal symmetry. Furthermore, the aggregate of such complex appeared to be spherical particles and fractal dendritic patterns.

In this paper we report a facile method for preparing co-immobilized enzyme and magnetic nanoparticles (MNPs) using metal coordinated hydrogel nanofibers. Candida rugosa lipase (CRL) was selected as guest protein. For good aqueous dispersity, low price and other unique properties, citric acid-modified magnetic iron oxide nanoparticles (CA-Fe3O4 NPs) have been widely used for immobilizing enzymes. As a result, the relative activity of CA-Fe3O4@Zn/AMP nanofiber-immobilized CRL increased by 8-fold at pH 10.0 and nearly 1-fold in a 50 °C water bath after 30 min, compared to free CRL. Moreover, the immobilized CRL had excellent long-term storage stability (nearly 80% releative activity after storage for 13 days). This work indicated that metal-nucleotide nanofibers could efficiently co-immobilize enzymes and MNPs simultaneously, and improve the stability of biocatalysts.

Amphiphilic dendritic macromolecules are suitable for the noncovalent encapsulation of guest molecules and could potentially be applied in drug-delivery systems. In this work, amphiphilic carbosilane dendrimers with peripheral poly(ethylene glycol) (PEG) units were synthesized using a hydrosilylation reaction, and their encapsulation properties were studied by fluorescence spectroscopy, using pyrene as the probe molecule. The results showed that the encapsulating capacity of the dendrimers increased as the number of PEG units increased, and that it also depended to some degree on the dendrimer generation.

BACKGROUND: Lonicera japonica Thunb. is a plant used in traditional Chinese medicine known for its anti-inflammatory, anti-oxidative, anti-carcinogenic, and antiviral pharmacological properties. The major active secondary metabolites of this plant are chlorogenic acid (CGA) and luteoloside. While the biosynthetic pathways of these metabolites are relatively well known, the genetic information available for this species, especially the biosynthetic pathways of its active ingredients, is limited. METHODOLOGY/PRINCIPAL FINDINGS: We obtained one million reads (average length of 400 bp) in a whole sequence run using a Roche/454 GS FLX titanium platform. Altogether, 85.69% of the unigenes covering the entire life cycle of the plant were annotated and 325 unigenes were assigned to secondary metabolic pathways. Moreover, 2039 unigenes were predicted as transcription factors. Nearly all of the possible enzymes involved in the biosynthesis of CGA and luteoloside were discovered in L. japonica. Three hydroxycinnamoyl transferase genes, including two hydroxycinnamoyl-CoA quinate hydroxycinnamoyl transferase genes and one hydroxycinnamoyl-CoA shikimate/quinate hydroxycinnamoyl transferase (HCT) gene featuring high similarity to known genes from other species, were cloned. The HCT gene was discovered for the first time in L. japonica. In addition, 188 candidate cytochrome P450 unigenes and 245 glycosyltransferase unigenes were found in the expressed sequence tag (EST) dataset. CONCLUSION: This study provides a high quality EST database for L. japonica by 454 pyrosequencing. Based on the EST annotation, a set of putative genes involved in CGA and luteoloside biosynthetic pathways were discovered. The database serves as an important source of public information on genetic markers, gene expression, genomics, and functional genomics in L. japonica.

Ophiocordyceps sinensis is a highly valuable and popular medicinal fungus used as a tonic and roborant for thousands of years in traditional Asian medicine. However, unsustainable harvesting practices have endangered this species and very little is known about its developmental programming, its biochemistry and genetics. To begin to address this, the transcriptome of the medicinal O. sinensis fruiting body was analyzed by high-throughput. In this O. sinensis 454-EST dataset, four mating type genes and 121 genes that may be involved in fruiting body development, especially in signal transduction and transcription regulation, were discovered. Moreover, a model was developed for the synthesis of the primary medicinal compound, cordycepin, and the putative biosynthetic enzymes identified. This transcriptome dataset provides a significant new resource for gene discovery in O. sinensis and dissection of its valuable biosynthetic and developmental pathways.

Surface patterns in ionic N‐isopropylacrylamide (N‐IPA) gels have been investigated under external constraint. Hexagonal, grain, and bubble patterns have been observed at temperatures below, near, and above the phase transition temperature Tc. It is found that the behavior of these patterns depends not only on temperature, time, and external constraint, but also on the thermal path. The time dependence of the gel thickness has revealed that there is a plateau period and that the end of the plateau period corresponds to the onset of the bubble pattern. This observation is in agreement with previous measurements of free spherical N‐IPA beads. The experiments show that each hexagonal cell evolves into a bubble for N‐IPA gels, while a bubble can be present in the middle of a hexagonal cell for acrylamide gels. The mechanism for the shrinking patterns will be also discussed.

Pattern formation and evolution in constrained acrylamide/sodium acrylate (PAAM/SA) gels have been investigated in acetone/water mixture. The constraint is achieved by cross linking the gel slabs onto a rigid substrate. All samples are initially kept in water with the hexagonal pattern develop on the surface before being immersed in the acetone/water mixture. Depending on the solvent composition and ionic strength of the sample, different patterns, i.e., hexagonal, grains, and bubbles, have been observed. These patterns are formed at acetone concentration below, near, and above the concentration at which the gel volume phase transition occurs. The wavelengths of hexagonal and bubble patterns are found to be the same, while that of the grain pattern is four times smaller. It is suggested that the shrinking patterns are formed due to the dense gel surface produced during the shrinking process.

The citrate reduction method for the synthesis of gold nanoparticles (GNPs) has known advantages but usually provides the products with low nanoparticle concentration and limits its application. Herein, we report a facile method to synthesize GNPs from concentrated chloroauric acid (2.5 mM) via adding sodium hydroxide and controlling the temperature. It was found that adding a proper amount of sodium hydroxide can produce uniform concentrated GNPs with low size distribution; otherwise, the largely distributed nanoparticles or instable colloids were obtained. The low reaction temperature is helpful to control the nanoparticle formation rate, and uniform GNPs can be obtained in presence of optimized NaOH concentrations. The pH values of the obtained uniform GNPs were found to be very near to neutral, and the pH influence on the particle size distribution may reveal the different formation mechanism of GNPs at high or low pH condition. Moreover, this modified synthesis method can save more than 90% energy in the heating step. Such environmental-friendly synthesis method for gold nanoparticles may have a great potential in large-scale manufacturing for commercial and industrial demand.

The ratio of bulk modulus to shear modulus, Ke/Ge, of polyacrylamide (PAAM) gels was studied. This ratio is directly related to a scaling exponent, δ, which is related to the concentration dependence of both bulk modulus and shear modulus. It was found that δ depends on the details of chemical ingredients and process. It increases as the crosslinker or monomer concentration increases. The behavior of acrylamide/sodium acrylate gel was found to be dramatically different from the nonionic gels. As sodium acrylate (SA) concentration increases from zero to 2 mol %, δ decreases from 2.09 to 1.08. Further increase of SA results in the formation of surface pattern and the value of δ increases slightly, eventually reaching a plateau around 1.25.

A novel, rapid, and economical method to isolate and purify natural sulforaphane from broccoli seeds is described. The procedure involves solvent extraction of autolyzed seed meal, followed by separation by solid phase extraction (SPE) and purification by preparative high-performance liquid chromatography (HPLC). The SPE method provides higher yield of sulforaphane from crude extracts compared to conventional liquid-liquid extraction. High purity and recovery of sulforaphane product can be obtained by preparative HPLC with a C 18 column and 30% methanol in water as the mobile phase. The purified compound was characterized by MS and (1)H and (13)C NMR. The techniques described here are useful tools in the preparative-scale isolation of sulforaphane in a fast, cost-effective, and waste-conscious manner.

Objective and design: Sectioned and ground enamel surfaces need to be etched with acid in order for the enamel structure to be exposed for study in the SEM. In the present study Retzius lines and prism cross-striations were observed in variably ground specimens after etching with nitric acid of different concentrations (0.1, 1, 2.5 and 5%) and for different time periods (15, 30, 45, 90 and 180 s). The aims were to improve our interpretation of these structures and to find the best etching regime. Results and conclusions: Retzius lines in the superficial enamel were more readily exposed than Retzius lines in deeper parts of the enamel. The former showed discontinuity defects that facilitated their identification, while the latter lacked such defects. Few deep Retzius lines were exposed and could first be identified with certainty after etching for 30 s in 1% acid. The structural and compositional basis for the visibility of deep Retzius lines may be subtle and difficult to identify. Scratches from the sectioning/grinding procedures may disturb their identification, but in general the grinding procedure was of minor importance for interpretation of enamel structure. Prism cross-striations were more readily exposed with the three stronger acid concentrations than with the weakest. They appeared as alternate light and dark bands, with a lower crystal concentration in the dark bands. No clear association with the prism varicosities/undulations was found. Etching with 1% nitric acid for 30 s seems to be a good compromise for the study of Retzius lines and prism cross-striations.

The phase behavior of a ternary system consisting of the hydrophobic ionic liquid (IL) 1-butyl-3-methylimidazolium hexafluorophosphate (bmimPF6), N,N-dimethylformamide, and water was investigated. Single-phase microemulsion and multiphase regions were observed in the ternary phase diagram. To the best of our knowledge, this is the first report of aqueous IL microemulsions prepared in the absence of traditional surfactants, i.e., surfactant-free microemulsions (SFMEs) containing IL. The microstructures and structural transitions of the aqueous IL SFMEs were investigated using cyclic voltammetry, electrical conductivity, and dynamic laser light scattering techniques. The results showed that the aqueous IL SFMEs exhibit IL-in-water, bicontinuous, and water-in-IL microstructures, similar to the case of traditional surfactant-based microemulsions. The three kinds of microstructures were confirmed from freeze-fracture electron microscopy observations. Ultraviolet-visible and fluorescence spectroscopies were used to examine the polarities of microdomains in the microemulsions, using methyl orange and pyrene, respectively, as probes. It was found that these two techniques can be used to identify the microstructures and microstructural transitions of the aqueous IL microemulsions.