In-Situ Intercalating of Silica Nanospheres into Polypyrrole During Its Electropolymerization to Prepare a Sorbent for Headspace Microextraction of Aldehydes in Edible Oils.

The quality of edible oils is significantly affected by autoxidation of lipids, which alters their flavor and nutritional quality through production of toxic materials like aldehydes (an important class of oil deterioration markers). Herein, an amino-silica nanospheres/polypyrrole (ASNS/PPy) nanocomposite sorbent was synthesized and used as the fiber coating for headspace solid-phase microextraction (HS-SPME) of aldehydes in edible oils, followed by gas chromatography (GC) separation and determination. Amino-silica nanoparticles were prepared by an amended Stöber method and composited with polypyrrole during its electropolymerization on the surface of a platinized stainless-steel fiber. The synergy between in-situ electropolymerization and rough surface of the platinized metal substrate created a durable fiber coating with unique uniformity, cohesiveness, and adsorption properties. The synthesized nanocomposite was characterized using Fourier transform infrared spectroscopy and scanning electron microscopy techniques. The performance of the prepared fiber was optimized by investigating the affecting variables including extraction temperature and time, stirring rate, and desorption conditions. The obtained limits of detection for hexanal and heptanal in sunflower oil were 0.005-0.009 µg mL-1. The prepared fiber exhibited excellent repeatability and reproducibility with the intra-fiber and inter-fiber relative standard deviations in the ranges of 3.9-8.8% and 7.3-15.1%, respectively. The proposed HS-SPME-GC strategy was successfully applied for the analysis of aldehydes in commercial edible oil samples.

Headspace solid-phase microextraction sampling of endogenous aldehydes in biological fluids using a magnetic metal-organic framework/polyaniline nanocomposite.

Nanoporosity, crystal structure, good thermal and mechanical stability, high surface-to-volume ratio, nanoscale cavities, and uniform pore topology have made metal-organic frameworks one of the best class of sorbents for adsorption/separation purposes. In this research, a metal-organic framework/polyaniline magnetite nanocomposite was synthesized and intercalated by polyaniline by electrophoretic deposition on the surface of a thin steel wire, to prepare a solid-phase microextraction fiber. It was coupled with gas chromatography-flame ionization detection and employed for the extraction and determination of aldehydes in biological samples. The magnetic nanocomposite was characterized using scanning electron microscopy, energy dispersive X-ray analysis, and Fourier transform infrared spectroscopy. Under the optimal experimental conditions, the calibration curves were linear in the range of 0.01-1 and 0.1-1 µg/L for hexanal and heptanal, respectively. The limits of detections for hexanal and heptanal were 0.001 and 0.01 µg/L, respectively. Intrafiber repeatability for six replicate analyses of 0.2 µg/L of the analytes was over the range 3.5-7.1%. Interfiber (fiber-to-fiber) reproducibility, calculated by six replicate analyses of the same concentration using three different fibers, and was found to be 10.4-15.7%. The developed procedure was successfully utilized for the analysis of hexanal and heptanal in human plasma and urine samples.

Bimetallic AuCu nanoclusters-based florescent chemosensor for sensitive detection of Fe3+ in environmental and biological systems.

Assays of ferric ion (Fe3+) with high sensitivity and selectivity have been required to evaluate its amount in environmental and biological systems. Herein, a novel fluorometric penicillamine-capped bimetallic gold-copper nanoclusters (PA-AuCu bi-MNCs) sensor was constructed for facile, environmentally friendly and quantitative detection of Fe3+ through inner filter effect (IFE) mechanism. One-step green synthetic approach was applied for the synthesis of AuCu bi-MNCs by using d-penicillamine (D-PA) as template and stabilizer. In the presence of Fe3+, the emission of the PA-AuCu bi-MNCs was hindered that caused selective quenching of the fluorescence intensity. The response to Fe3+ allows for two linear dynamic ranges of 5.0 × 10-7 M-7.0 × 10-6 M and 7.0 × 10-6 M-1.0 × 10-4 M with a detection limit of 0.1 µM, which is approximately 53 times lower than the maximum level (5.37 µM) of Fe3+ in drinking water that had been reported by the World Health Organization. The independency of the system from most of the interferences is the important feature of this work. Beside the appropriate selectivity of the proposed method, it shows a considerable operation in various environmental samples including rain water, three types of river water and also in human blood serum as a biological matrix.

Synthesis and characterization of MIL-101(Cr) intercalated by polyaniline composite, doped with silica nanoparticles and its evaluation as an efficient solid-phase extraction sorbent.

A metal-organic framework/polyaniline composite was synthesized and doped with silica nanoparticles. The structure and morphology of the composite were characterized using Fourier transform infrared spectroscopy and scanning electron microscopy. It was packed inside a cartridge and evaluated for the solid-phase extraction of thymol and carvacrol, followed by gas chromatography with flame ionization detection measurement. The influence of the important experimental variables on the efficiency of the proposed method, including pH, ionic strength, volume of sample solution and type, and volume of eluent were studied and optimized. Under the optimal conditions, the relative standard deviations were found to be 3.8 and 9.8% for thymol and carvacrol, respectively, and the corresponding limits of detection were 0.1 and 1.0 ng/mL. The linear dynamic ranges for the calibration curves of the analytes were 10-10000 ng/mL, with determination coefficients (R2 ) > 0.993. The limits of quantifications were found to be 0.01 and 0.5 µg/mL, for thymol and carvacrol, respectively. The prepared nanocomposite sorbent was applied successfully to the extraction and determination of thymol and carvacrol in Lamiaceae plant extracts and a honey sample, with relative recoveries in the range of 90.28-122.0%.

Iron oxide/silica/polypyrrole nanocomposite sorbent for the comparison study of direct-immersion and headspace solid-phase microextraction of aldehyde biomarkers in human urine.

The short chain alkyl aldehydes, especially hexanal and heptanal, in urine are considered as potential biomarkers of several diseases and their determination in biological fluids has gained a great attention in recent years. Magnetic iron oxide core-shell silica (Fe3O4/SiO2) nanoparticles was synthesized and embedded in polypyrrole (PPy) during the in-situ electropolymerization on the surface of a stainless-steel wire. The Fe3O4/SiO2/PPy coated steel wire was used as a novel and effective solid-phase microextraction (SPME) fibre. It was employed for the extraction and preconcentration of hexanal and heptanal through direct-immersion (DI-) and headspace (HS-) SPME sampling strategies, followed by GC-FID quantification. The prepared nanocomposite fiber was characterized by scanning electron microscopy (SEM) and Fourier transform infrared spectroscopy (FT-IR). All influential variables on the extraction efficiency of the DI- and HS-SPME sampling modes were studied and optimized. The calibration curves showed acceptable linearity (R2 > 0.99) over the range of 0.01-10 µg mL-1 for the DI-SPME-GC-FID and 0.01-15 µgmL-1 for HS-SPME-GC-GID methods. The limit of detections (LODs) corresponding to the analytes amounts for which signal-to-noise ratios were equal to 3, estimated to be 0.1 and 0.5 ng mL-1, for hexanal and heptanal using HS-SPME-GC-FID, respectively. The LODs for DI-SPME-GC-FID method were 0.1 and 1.0 for hexanal and heptanal. For six replicated analyses of 0.5 µg mL-1 of the analytes, the relative standard deviations (RSDs) were calculated 6.5-6.6% and 5.1-5.3%, for DI-SPME and HS-SPME, respectively. The two developed methods were successfully applied for analysis of hexanal and heptanal in urine samples without derivatization step. The HS-SPME-GC-FID sampling/determination strategy showed better analytical figures of merit and longer lifetime for the prepared nanocomposite fiber.

Comparison of the Conventional and Electroenhanced Direct-Immersion Solid-Phase Microextraction for Sampling of Nicotine in Biological Fluids of the Human Body.

A stainless steel fiber was made porous and adhesive by platinization and then coated by nanostructured polypyrrole (PPy), using an appropriate electrophoretic deposition (EPD) method. The morphological surface structure and functional groups of the PPy-coated fiber were studied using SEM (Scanning electron microscope) instrument. The prepared fiber was used for comparison of direct immersion (DI) and electroenhanced direct immersion solid-phase microextraction (EE-DI-SPME) of nicotine in human plasma and urine samples followed by gas chromatography flame ionization detector (GC-FID) determination. The effects of the influential experimental parameters on the efficiency of the DI-SPME and EE-DI-SPME methods, including the pH and ionic strength of the sample solution, applied Direct current (DC) voltage, extraction temperature and time and stirring rate, were optimized. Under the optimal conditions, the calibration curves for the DI-SPME-GC-FID and EE-DI-SPME-GC-FID methods were linear over the ranges of 0.1⁻10.0 µg mL-1 and 0.001⁻10.0 µg mL-1, respectively. The relative standard deviations (RSDs, n = 6) were found to be 6.1% and 4.6% for the DI and EE strategies, respectively. The LODs (limit of detection) of the DI-SPME-GC-FID and EE-DI-SPME-GC-FID methods were found to be 10 and 0.3 ng mL-1, respectively. The relative recovery values (for the analysis of 1 µg mL-1 nicotine) were found to be 91⁻110% for EE-DI-SPME and 75⁻105% for DI-SPME. The enrichment factors for DI-SPME and EE-DI-SPME sampling were obtained as 38,734 and 50,597, respectively. The results indicated that EE-SPME was more efficient for quantitation of nicotine in biological fluids. The developed procedure was successfully carried out for the extraction and measurement of nicotine in real plasma and urine samples.

A Deep Hidden Diversity of Dictyostelia.

Dictyostelia is a monophyletic group of transiently multicellular (sorocarpic) amoebae, whose study is currently limited to laboratory culture. This tends to favour faster growing species with robust sorocarps, while species with smaller more delicate sorocarps constitute most of the group's taxonomic breadth. The number of known species is also small (∼150) given Dictyostelia's molecular depth and apparent antiquity (>600 myr). Nonetheless, dictyostelid sequences are rarely recovered in culture independent sampling (ciPCR) surveys. We developed ciPCR primers to specifically target dictyostelid small subunit (SSU or 18S) rDNA and tested them on total DNAs extracted from a wide range of soils from five continents. The resulting clone libraries show mostly dictyostelid sequences (∼90%), and phylogenetic analyses of these sequences indicate novel lineages in all four dictyostelid families and most genera. This is especially true for the species-rich Heterostelium and Dictyosteliaceae but also the less species-rich Raperosteliaceae. However, the most novel deep branches are found in two very species-poor taxa, including the deepest branch yet seen in the highly divergent Cavenderiaceae. These results confirm a deep hidden diversity of Dictyostelia, potentially including novel morphologies and developmental schemes. The primers and protocols presented here should also enable more comprehensive studies of dictyostelid ecology.

A high area, porous and resistant platinized stainless steel fiber coated by nanostructured polypyrrole for direct HS-SPME of nicotine in biological samples prior to GC-FID quantification.

The surface of a stainless steel fiber was made porous, resistant and cohesive using electrophoretic deposition and coated by the nanostructured polypyrrole using an amended in-situ electropolymerization method. The coated fiber was applied for direct extraction of nicotine in biological samples through a headspace solid-phase microextraction (HS-SPME) method followed by GC-FID determination. The effects of the important experimental variables on the efficiency of the developed HS-SPME-GC-FID method, including pH of sample solution, extraction temperature and time, stirring rate, and ionic strength were evaluated and optimized. Under the optimal experimental conditions, the calibration curve was linear over the range of 0.1-20µgmL-1 and the detection limit was obtained 20ngmL-1. Relative standard deviation (RSD, n=6) was calculated 7.6%. The results demonstrated the superiority of the proposed fiber compared with the most used commercial types. The proposed HS-SPME-GC-FID method was successfully used for the analysis of nicotine in urine and human plasma samples.

Amino-silica/graphene oxide nanocomposite coated cotton as an efficient sorbent for needle trap device.

Cotton and silica are easily available and plentiful natural materials, with significant sorptive properties, which can be provided easily at low prices. In this research, a novel and effective sorbent was synthesized by covalent attachment of amino-silica/graphene oxide nanocomposite to the cotton (Cot/GO/Si) and packed into a stainless steel needle for preparation a needle trap device (NTD). The nanocomposite sorbent was characterized by SEM and FT-IR. The Cot/GO/Si packed NTD was used for direct extraction of PAHs from polluted soil samples, followed by GC-FID measurement. Different affecting experimental variables, including extraction temperature, flow rate, desorption time and temperature were studied and optimized. Under the optimal conditions, good linearity of the calibration curves (R2 > 0.99) was obtained over the concentration range of 0.01-1.0 µg g-1. The limits of detection, limits of quantification and relative standard deviations were found to be in the ranges of 0.05-0.17 ng g-1, 0.2-0.6 ng g-1 and 9.7-15.4% (n = 6), respectively. Finally, the proposed NTD-GC-FID method was successfully applied for the extraction and determination of PAHs in contaminated soil samples.

A solid-phase microextraction platinized stainless steel fiber coated with a multiwalled carbon nanotube-polyaniline nanocomposite film for the extraction of thymol and carvacrol in medicinal plants and honey.

A mechanically hard and cohesive porous fiber, with large surface area, for more strong attachment of the coating was provided by platinizing a stainless steel wire. Then, the platinized stainless steel fiber was coated with a multiwalled carbon nanotube/polyaniline (MWCNT/PANI) nanocomposite using electrophoretic deposition (EPD) method and applied for the extraction of thymol and carvacrol with direct-immersion solid-phase microextraction (DI-SPME) method followed by high-performance liquid chromatography-ultraviolet detection (HPLC-UV) quantification. To provide a larger coarse surface for the tightened attachment of coating on the fiber, a stainless steel wire was platinized using a suitable optimized EPD method. Different experimental parameters were studied and the optimal conditions were obtained as: pH of the sample solution: 2; extraction time: 60min; salt content in the sample solution: 1% w/v NaNO3; desorption time: 60min; type and volume of the desorption solvent: acetonitrile, 100µL. Under the optimized conditions, limits of detection (LODs) were 0.6 and 0.8µgmL(-1) for thymol and carvacrol, respectively. Linear dynamic range (LDR) for the calibration curves of both analytes were 1-80µgmL(-1). Relative standard deviation (RSD%, n=6) was 6.8 for thymol and 12.7 for carvacrol. The proposed fiber was successfully applied for the recovery and determination of thymol and carvacrol in thyme, savory, and honey samples.

Arnica (Asteraceae) phylogeny revisited using RPB2: complex patterns and multiple d-paralogues.

The region coding for the second largest subunit of RNA polymerase II (RPB2) was explored for resolving interspecific relationships in Arnica and lower level taxa in general. The region between exons 17 and 23 was cloned and sequenced for 33 accessions of Arnica and four outgroup taxa. Three paralogues of the RPB2-d copy (RPB2-dA, B and C) were detected in Arnica and outgroup taxa, indicating that the duplications must have occurred before the divergence of Arnica. Parsimony and Bayesian analyses of separate alignments of the three copies reveal complex patterns in Arnica, likely reflecting a history of lineage sorting in combination with apomixis, polyploidization, and possibly hybridization. Cloned sequences of some taxa do not form monophyletic clades within paralogues, but form multiple strongly supported clades with sequences of other taxa. Some well supported groups are present in more than one paralogue and many groups are in line with earlier hypotheses regarding interspecific relationships within the genus. Low levels of homoplasy in combination with relatively high sequence variation indicates that the introns of the RPB2 region could be suitable for phylogenetic studies in low level taxonomy.

Use of allele-specific sequencing primers is an efficient alternative to PCR subcloning of low-copy nuclear genes.

Direct Sanger sequencing of polymerase chain reaction (PCR)-amplified nuclear genes leads to polymorphic sequences when allelic variation is present. To overcome this problem, most researchers subclone the PCR products to separate alleles. An alternative is to directly sequence the separate alleles using allele-specific primers. We tested two methods to enhance the specificity of allele-specific primers for use in direct sequencing: using short primers and amplification refractory mutation system (ARMS) technique. By shortening the allele-specific primer to 15-13 nucleotides, the single mismatch in the ultimate base of the primer is enough to hinder the amplification of the nontarget allele in direct sequencing and recover only the targeted allele at high accuracy. The deliberate addition of a second mismatch, as implemented in the ARMS technique, was less successful and seems better suited for allele-specific amplification in regular PCR rather than in direct sequencing.

Conflicting phylogenetic signals in the SlX1/Y1 gene in Silene.

BACKGROUND: Increasing evidence from DNA sequence data has revealed that phylogenies based on different genes may drastically differ from each other. This may be due to either inter- or intralineage processes, or to methodological or stochastic errors. Here we investigate a spectacular case where two parts of the same gene (SlX1/Y1) show conflicting phylogenies within Silene (Caryophyllaceae). SlX1 and SlY1 are sex-linked genes on the sex chromosomes of dioecious members of Silene sect. Elisanthe. RESULTS: We sequenced the homologues of the SlX1/Y1 genes in several Sileneae species. We demonstrate that different parts of the SlX1/Y1 region give different phylogenetic signals. The major discrepancy is that Silene vulgaris and S. sect. Conoimorpha (S. conica and relatives) exchange positions. To determine whether gene duplication followed by recombination (an intralineage process) may explain the phylogenetic conflict in the Silene SlX1/Y1 gene, we use a novel probabilistic, multiple primer-pair PCR approach. We did not find any evidence supporting gene duplication/loss as explanation to the phylogenetic conflict. CONCLUSION: The phylogenetic conflict in the Silene SlX1/Y1 gene cannot be explained by paralogy or artefacts, such as in vitro recombination during PCR. The support for the conflict is strong enough to exclude methodological or stochastic errors as likely sources. Instead, the phylogenetic incongruence may have been caused by recombination of two divergent alleles following ancient interspecific hybridization or incomplete lineage sorting. These events probably took place several million years ago. This example clearly demonstrates that different parts of the genome may have different evolutionary histories and stresses the importance of using multiple genes in reconstruction of taxonomic relationships.

Phylogenetics of asterids based on 3 coding and 3 non-coding chloroplast DNA markers and the utility of non-coding DNA at higher taxonomic levels.

Asterids comprise 1/4-1/3 of all flowering plants and are classified in 10 orders and >100 families. The phylogeny of asterids is here explored with jackknife parsimony analysis of chloroplast DNA from 132 genera representing 103 families and all higher groups of asterids. Six different markers were used, three of the markers represent protein coding genes, rbcL, ndhF, and matK, and three other represent non-coding DNA; a region including trnL exons and the intron and intergenic spacers between trnT (UGU) to trnF (GAA); another region including trnV exons and intron, trnM and intergenic spacers between trnV (UAC) and atpE, and the rps16 intron. The three non-coding markers proved almost equally useful as the three coding genes in phylogenetic reconstruction at the high level of orders and families in asterids, and in relation to the number of aligned positions the non-coding markers were even more effective. Basal interrelationships among Cornales, Ericales, lamiids (new name replacing euasterids I), and campanulids (new name replacing euasterids II) are resolved with strong support. Family interrelationships are fully or almost fully resolved with medium to strong support in Cornales, Garryales, Gentianales, Solanales, Aquifoliales, Apiales, and Dipsacales. Within the three large orders Ericales, Lamiales, and Asterales, family interrelationships remain partly unclear. The analysis has contributed to reclassification of several families, e.g., Tetrameristaceae, Ebenaceae, Styracaceae, Montiniaceae, Orobanchaceae, and Scrophulariaceae (by inclusion of Pellicieraceae, Lissocarpaceae, Halesiaceae, Kaliphoraceae, Cyclocheilaceae, and Myoporaceae+Buddlejaceae, respectively), and to the placement of families that were unplaced in the APG-system, e.g., Sladeniaceae, Pentaphylacaceae, Plocospermataceae, Cardiopteridaceae, and Adoxaceae (in Ericales, Ericales, Lamiales, Aquifoliales, and Dipsacales, respectively), and Paracryphiaceae among campanulids. Several families of euasterids remain unclassified to order.