Ionomic profiling of Nicotiana langsdorffii wild-type and mutant genotypes exposed to abiotic stresses

To provide a new insight into the response of plants to abiotic stresses, the ionomic profiles of Nicotiana langsdorffii specimens have been determined before and after exposure to toxic metals (chromium) or drought conditions. The plants were genetically transformed with the rat glucocorticoid receptor (GR) or the gene for Agrobacterium rhizogenes rolC, because these modifications are known to produce an imbalance in phytohormone equilibria and a significant change in the defence response of the plant. Elemental profiles were obtained by developing and applying analytical procedures based on inductively coupled plasma atomic emission and mass spectrometry (ICP–AES/MS). In particular, the removal of isobaric interferences affecting the determination of Cr and V by ICP–MS was accomplished by use of a dynamic reaction cell, after optimization of the relevant conditions. The combined use of ICP atomic emission and mass spectrometry enabled the determination of 29 major and trace elements (Ba, Bi, Ca, Cd, Co, Cr, Cu, Eu, Fe, Ga, K, Li, Mg, Mn, Mo, Na, P, Pb, Pt, Rb, S, Sb, Sn, Sr, Te, V, W, Y, and Zn) in different parts of the plants (roots, stems, and leaves), with high accuracy and precision. Multivariate data processing and study of element distribution patterns provided new information about the ionomic response of the target organism to chemical treatment or water stress. Genetic modification mainly affected the distribution of Bi, Cr, Mo, Na, and S, indicating that these elements were involved in biochemical processes controlled by the GR or rolC genes. Chemical stress strongly affected accumulation of several elements (Ba, Ca, Fe, Ga, K, Li, Mn, Mo, Na, P, Pb, Rb, S, Sn, Te, V, and Zn) in different ways; for Ca, Fe, K, Mn, Na, and P the effect was quite similar to that observed in other studies after treatment with other transition elements, for example Cu and Cd. The effect of water deficit was less evident, mainly consisting in a decrease of Ba, Cr, Na, and Sr in roots.

Analysis of egg-based model wall paintings by use of an innovative combined dot-ELISA and UPLC-based approach

The chemical analysis of egg-based wall paintings—the mezzo fresco technique—is an interesting topic in the characterisation of organic binders. A revised procedure for a dot-enzyme-linked immunosorbent assay (dot-ELISA) able to detect protein components of egg-based wall paintings is reported. In the new dot-ELISA procedure we succeeded in maximizing the staining colour by adjusting the temperature during the staining reaction. Quantification of the colour intensity by visible reflectance spectroscopy resulted in a straight line plot of protein concentration against reflectance in the wavelength range 380–780 nm. The modified dot-ELISA procedure is proposed as a semi-quantitative analytical method for characterisation of protein binders in egg-based paintings. To evaluate its performance, the method was first applied to standard samples (ovalbumin, whole egg, egg white), then to model specimens, and finally to real samples (Giotto’s wall paintings). Moreover, amino acid analysis performed by innovative ultra-performance liquid chromatography was applied both to standards and to model samples and the results were compared with those from the dot-ELISA tests. In particular, after protein hydrolysis (24 h, 114 °C, 6 mol L^?1 HCl) of the samples, amino acid derivatization by use of 6-aminoquinolyl-N-hydroxysuccinimidyl carbamate enabled reproducible analysis of amino acids. This UPLC amino acid analysis was rapid and reproducible and was applied for the first time to egg-based paintings. Because the painting technique involved the use of egg-based tempera on fresh lime-based mortar, the study enabled investigation of the effect of the alkaline environment on egg-protein detection by both methods.

Modulation of direct electron transfer of cytochrome c by use of a molecularly imprinted thin film

We describe the preparation of a molecularly imprinted polymer film (MIP) on top of a self-assembled monolayer (SAM) of mercaptoundecanoic acid (MUA) on gold, where the template cytochrome c (cyt c) participates in direct electron transfer (DET) with the underlying electrode. To enable DET, a non-conductive polymer film is electrodeposited from an aqueous solution of scopoletin and cyt c on to the surface of a gold electrode previously modified with MUA. The electroactive surface concentration of cyt c was 0.5 pmol cm^?2. In the absence of the MUA layer, no cyt c DET was observed and the pseudo-peroxidatic activity of the scopoletin-entrapped protein, assessed via oxidation of Ampliflu red in the presence of hydrogen peroxide, was only 30 % of that for the MIP on MUA. This result indicates that electrostatic adsorption of cyt c by the MUA–SAM substantially increases the surface concentration of cyt c during the electrodeposition step, and is a prerequisite for the productive orientation required for DET. After template removal by treatment with sulfuric acid, rebinding of cyt c to the MUA–MIP-modified electrode occurred with an affinity constant of 100,000 mol^?1 L, a value three times higher than that determined by use of fluorescence titration for the interaction between scopoletin and cyt c in solution. The DET of cyt c in the presence of myoglobin, lysozyme, and bovine serum albumin (BSA) reveals that the MIP layer suppresses the effect of competing proteins.     

Characterisation and quantification of liposome-type nanoparticles in a beverage matrix using hydrodynamic chromatography and MALDI–TOF mass spectrometry

This paper describes the characterisation of liposome-type nanoparticles (NPs) dispersed in a beverage matrix. Characterisation is based on a two-step procedure: first, liposomes are separated on the basis of size in the nanometre range by use of hydrodynamic chromatography (HDC); second, chemical characterisation is performed by use of MALDI–TOF mass spectrometry (MS). Characterisation of three types of Coatsome liposome, a commercially available type of empty liposome, was investigated. All three liposome types, Coatsome A?=?anionic, N?=?neutral, and C?=?cationic, gave single peaks in HDC, reflecting diameters of 153, 187, and 205 nm, respectively. Subsequent MALDI–TOF MS in positive mode furnished major signals at m/z?=?734.5 ([M?+?H]⁺ adduct) and m/z?=?756.6 ([M?+?Na]⁺ adduct) of l-(α)-dipalmitoylphosphatidylcholine (DPPC) monomer and dimeric adducts at m/z?=?1468.1 and m/z?=?1490.1, respectively. MALDI–TOF MS in negative mode gave a signal at m/z?=?721.3 ([M???H]^? adduct) of l-(α)-dipalmitoylphosphatidylglycerol (DPPG), except for Coatsome C which lacks this phospholipid. After HDC separation of Coatsome A NPs the major DPPC and DPPG signals can be detected in the expected fractions by use of MALDI–TOF MS in positive and negative modes, respectively. Validation of the analytical strategy revealed linearity (R ²?>?0.99), repeatability (relative standard deviation <10 %), and reproducibility (relative standard deviation between days <10 %) were good, recovery was 61?±?5 %, and the limit of quantification was 1 mg?mL^?1 in this matrix. With 4 mg Coatsome A mL^?1 20 out of 20 samples furnished the 734.5 and 756.6 signals typical of DPPC in MALDI–TOF MS characterisation.     

A quantitative and comprehensive method to analyze human milk oligosaccharide structures in the urine and feces of infants

Human milk oligosaccharides (HMOs), though non-nutritive to the infant, shape the intestinal microbiota and protect against pathogens during early growth and development. Infant formulas with added galacto-oligosaccharides have been developed to mimic the beneficial effects of HMOs. Premature infants have an immature immune system and a leaky gut and are thus highly susceptible to opportunistic infections. A method employing nanoflow liquid chromatography time-of-flight mass spectrometry (MS) is presented to simultaneously identify and quantify HMOs in the feces and urine of infants, of which 75 HMOs have previously been fully structurally elucidated. Matrix-assisted laser desorption/ionization Fourier transform ion cyclotron resonance MS was employed for high-resolution and rapid compositional profiling. To demonstrate this novel method, samples from mother–infant dyads as well as samples from infants receiving infant formula fortified with dietary galacto-oligosaccharides or probiotic bifidobacteria were analyzed. Ingested oligosaccharides are demonstrated in high abundance in the infant feces and urine. While the method was developed to examine specimens from preterm infants, it is of general utility and can be used to monitor oligosaccharide consumption and utilization in term infants, children, and adults. This method may therefore provide diagnostic and therapeutic opportunities.

Determination of tenuazonic acid in human urine by means of a stable isotope dilution assay

The content of tenuazonic acid in human urine was determined by a stable isotope dilution assay (SIDA) that was recently developed for the analysis of food commodities and extensively re-validated for urine matrix in this study. Linearity of the response curve was proven between molar ratios n(labeled standard)/n(analyte) of 0.02–100. The limits of detection and determination were 0.2 and 0.6 μg/L, respectively. The mean recovery of the stable isotope dilution assay was 102?±?3 % in the range between 1.0 and 100 μg/L. Interassay precision was 6.7 % (relative standard deviation of three triplicate analyses of a human urine sample during 3 weeks). The method was applied to two studies dealing with urinary excretion of tenuazonic acid: In the first study, tenuazonic acid was quantified in the 24-h urine of six volunteers from Germany (three female, three male) in a concentration range of 1.3–17.3 μg/L or 2.3–10.3 ng/mg^?1 creatinine, respectively. In the second study, two volunteers (one female, one male) ingested 30 μg tenuazonic acid by consumption of naturally contaminated whole meal sorghum infant cereals and tomato juice, respectively. The urinary excretion of the ingested tenuazonic acid was 54–81 % after 6 h, depending on matrix and volunteer. After 24 h, 87–93 % of the ingested amount of tenuazonic acid was excreted, but the fate of the remaining about 10 % is open. Thus, it is not possible to exclude potential health hazards for the consumer, completely.

Stabilization of the Triphosphallyl Ligand η3‐P3{P(O)H} at Iridium via Alkaline Activation of P4

The selective functionalization of the polyphosphorus moiety Ph₂PCH₂PPh₂PPPP present as a tetrahapto‐ligand in complex [Ir(dppm)(Ph₂PCH₂PPh₂PPPP)]⁺ ( 1 , dppm=Ph₂PCH₂PPh₂) was obtained by reaction of 1 with water under basic conditions at room temperature. The formation of the new triphosphaallyl moiety η³‐P₃{P(O)H} was determined in solution by NMR spectroscopy, and confirmed in the solid state by a single‐crystal X‐ray structure of the stable product [Ir(κ²‐dppm)(κ¹‐dppm)(η³‐P₃{P(O)H})] ( 2 ). In solution, 2 has a fluxional behavior attributable to the four P atoms belonging to the tetraphosphorus moiety in 1 and exhibits a chemical exchange process involving the two PPh₂ moieties of the same bidentate ligand, as determined by 1D and 2D NMR spectroscopy experiments carried out at variable temperature. The mechanism of the reaction was investigated at the DFT level, which suggested a selective attack of an in‐situ generated OH^? anion on one of the non‐coordinated phosphorus atoms of the P₄ moiety. The reaction then evolves through an acid‐assisted tautomerization, which leads to the final compound 2 . Bonding analysis pointed out that the new unsubstituted P₃‐unit in the η³‐P₃{P(O)H} moiety behaves as a triphosphallyl ligand.     

Erratum to: “In vitro biological activity comparison of some hydroxyapatite-based composite materials using simulated body fluid”

The original version of the article was published in Cent. Eur. J. Chem. 11(10) (2013) pp. 1583–1598. Unfortunately, the original version of this article contains a mistake in the affiliation section. The affiliation for R?zvan Stefan is Veterinary Medicine Faculty, University of Agricultural Science and Veterinary Medicine, RO-400372 Cluj Napoca, Romania.     

Mechanical, thermal and surface properties of polyacrylamide/dextran semi-interpenetrating network hydrogels tuned by the synthesis temperature

The mechanical, rheological, thermal, and surface behaviors of three polyacrylamide/dextran (PAAm/Dx) semi-interpenetrating polymer network (semi-IPN) hydrogels, prepared at 22°C, 5°C and ?18°C, were investigated. The results were compared with those obtained on cross-linked PAAm without Dx synthesized under the same conditions. Hydrogels prepared at the lowest temperature were the most mechanically stable. The thermal stability of the semi-IPN hydrogels is slightly lower than the corresponding PAAm gels, irrespective of preparation temperature. The water vapor sorption capacity depended on the presence of Dx as well as preparation temperature, which determines the network morphology.