Relationship between Phenolic Compounds,Antioxidant Properties,and the Allergenic Protein Mal d 1 in Different Selenium-Biofortified Apple Cultivars (Malus domestica)

Notable parts of the population in Europe suffer from allergies towards apples. To address this health problem, the analysis of the interactions of relevant allergens with other substances such as phenolic compounds is of particular importance. The aim of this study was to evaluate the correlations between the total phenolic content (TPC), polyphenol oxidase (PPO) activity, antioxidant activity (AOA), and the phenolic compound profile and the content of the allergenic protein Mal d 1 in six apple cultivars. It was found that the PPO activity and the content of individual phenolic compounds had an influence on the Mal d 1 content. With regard to the important constituents, flavan-3-ols and phenolic acids, it was found that apples with a higher content of chlorogenic acid and a low content of procyanidin trimers and/or epicatechin had a lower allergenic potential. This is probably based on the reaction of phenolic compounds (when oxidized by the endogenous PPO) with proteins, thus being able to change the conformation of the (allergenic) proteins, which further corresponds to a loss of antibody recognition. When apples were additionally biofortified with selenium, the composition of the apples, with regard to TPC, phenolic profile, AOA, and PPO, was significantly affected. Consequently, this innovative agronomic practice seems to be promising for reducing the allergenic potential of apples.     

Drying of a cellulose II gel: effect of physical modification and redispersibility in water

The agglomeration of cellulosic materials upon drying, often called hornification, causes a reduction of water retention, among other undesired effects. It is one of the main issues in industrial cellulose processing, especially with regard to nanocelluloses. As a consequence, high transportation and storage costs arise since nanocelluloses need to remain in aqueous suspensions unless trade-offs in reactivity, redispersibility and surface properties are accepted. In this study, different drying strategies for TENCEL^® gel, a nanostructured gel derived from the Lyocell process consisting of spherical particles, are compared and evaluated. First, freeze-drying with consideration of the influence of freezing temperature and the use of tert-butanol as cryo-protectant, and second, simple oven-drying at 60 °C. Surprisingly, oven-dried xerogels showed higher water retention values and also better colloidal stability than the cryogels. This is in stark contrast to cellulose nanofibrils for which freeze-drying has been shown to be significantly superior to oven drying in terms of redispersibility. For the TENCEL^® gel, oven-drying was thus selected and the influence of additives on the redispersibility of the cellulose II gel was studied by means of the common water retention value, particle size, colloidal stability, appearance of the redispersed gel and viscosity. The addition of the polysaccharides carboxymethyl cellulose or xanthan showed the most promising results with regard to redispersibility. Also sucrose and ammonium bicarbonate provided higher colloidal stabilities than that of the untreated TENCEL^® gel. The redispersibility of the cellulose II xerogels could thus be significantly improved by simple and cost-efficient mixing with additives prior to drying.     

ChemInform Abstract: Temperature Induced Phase Transition of CaMn0.5Zr1.5(PO4)3 Phosphate.

In view of a known structural phase transition at 800—875 °C and the by 10 times increased luminescence of Mn²⁺ in the high‐temperature phase, low‐ (LT) and high‐temperature (HT) polymorphs of CaMn_0.5Zr_1.5(PO₄)₃ are prepared by sol—gel reaction of Mn(O‐Ac)₂, Ca(NO₃)₂, ZrOCl₂, and NH₄H₂PO₄ in ethylene glycol followed by a final annealing (700 or 900 °C, 20 h, resp.).     

Bright,Highly Water‐Soluble Triazacyclononane Europium Complexes To Detect Ligand Binding with Time‐Resolved FRET Microscopy

Luminescent europium complexes are used in a broad range of applications as a result of their particular emissive properties. The synthesis and application of bright, highly water‐soluble, and negatively charged sulfonic‐ or carboxylic acid derivatives of para‐substituted aryl–alkynyl triazacyclononane complexes are described. Introduction of the charged solubilizing moieties suppresses cellular uptake or adsorption to living cells making them applicable for labeling and performing assays on membrane receptors. These europium complexes are applied to monitor fluorescent ligand binding on cell‐surface proteins with time‐resolved Förster resonance energy transfer (TR‐FRET) assays in plate‐based format and using TR‐FRET microscopy.     

Sizing up large protein complexes by electrospray ionisation-based electrophoretic mobility and native mass spectrometry: morphology selective binding of Fabs to hepatitis B virus capsids

The capsid of hepatitis B virus (HBV) is a major viral antigen and important diagnostic indicator. HBV capsids have prominent protrusions (‘spikes’) on their surface and are unique in having either T?=?3 or T?=?4 icosahedral symmetry. Mouse monoclonal and also human polyclonal antibodies bind either near the spike apices (historically the ‘α-determinant’) or in the ‘floor’ regions between them (the ‘β-determinant’). Native mass spectrometry (MS) and gas-phase electrophoretic mobility molecular analysis (GEMMA) were used to monitor the titration of HBV capsids with the antigen-binding domain (Fab) of mAb 3120, which has long defined the β-determinant. Both methods readily distinguished Fab binding to the two capsid morphologies and could provide accurate masses and dimensions for these large immune complexes, which range up to ~8 MDa. As such, native MS and GEMMA provide valuable alternatives to a more time-consuming cryo-electron microscopy analysis for preliminary characterisation of virus-antibody complexes.

Convenient and Mild Epoxidation of Alkenes Using Heterogeneous Cobalt Oxide Catalysts

A general epoxidation of aromatic and aliphatic olefins has been developed under mild conditions using heterogeneous Co_xO_y–N/C (x=1,3; y=1,4) catalysts and tert‐butyl hydroperoxide as the terminal oxidant. Various stilbenes and aliphatic alkenes, including renewable olefins, and vitamin and cholesterol derivatives, were successfully transformed into the corresponding epoxides with high selectivity and often good yields. The cobalt oxide catalyst can be recycled up to five times without significant loss of activity or change in structure. Characterization of the catalyst by XRD, TEM, XPS, and EPR analysis revealed the formation of cobalt oxide nanoparticles with varying size (Co₃O₄ with some CoO) and very few large particles with a metallic Co core and an oxidic shell. During the pyrolysis process the nitrogen ligand forms graphene‐type layers, in which selected carbon atoms are substituted by nitrogen.     

(1‐Butyl‐4‐methyl‐pyridinium)[Cu(SCN)2]: A Coordination Polymer and Ionic Liquid

The compound (C₄C₁py)[Cu(SCN)₂], (C₄C₁py=1‐Butyl‐4‐methyl‐pyridinium), which can be obtained from CuSCN and the ionic liquid (C₄C₁py)(SCN), turns out to be a new organic–inorganic hybrid material as it qualifies both, as a coordination polymer and an ionic liquid. It features linked [Cu(SCN)₂]^? units, in which the thiocyanates bridge the copper ions in a μ_1,3‐fashion. The resulting one‐dimensional chains run along the a axis, separated by the C₄C₁py counterions. Powder X‐ray diffraction not only confirms the single‐crystal X‐ray structure solution but proves the reformation of the coordination polymer from an isotropic melt. However, the materials shows a complex thermal behavior often encountered for ionic liquids such as a strong tendency to form a supercooled melt. At a relatively high cooling rate, glass formation is observed. When heating this melt in differential scanning calorimetry (DSC) and temperature‐dependent polarizing optical microscopy (POM), investigations reveal the existence of a less thermodynamically stable crystalline polymorph. Raman measurements conducted at 10 and 100 °C point towards the formation of polyanionic chain fragments in the melt. Solid‐state UV/Vis spectroscopy shows a broad absorption band around 18 870 cm^?1 (530 nm) and another strong one below 20 000 cm^?1 (<500 nm). The latter is attributed to the d(Cu^I)→π*(SCN)‐MLCT (metal‐to‐ligand charge transfer) transition within the coordination polymer yielding an energy gap of 2.4 eV. At room temperature and upon irradiation with UV light, the material shows a weak fluorescence band at 15 870 cm^?1 (630 nm) with a quantum efficiency of 0.90(2) % and a lifetime of 131(2) ns. Upon lowering the temperature, the luminescence intensity strongly increases. Simultaneously, the band around 450 nm in the excitation spectrum decreases.     

Oligonucleotide Analogues with Integrated Bases and Backbone (ONIB). Part 31

The self‐complementary guanosine‐ and cytidine‐derived aminomethylene‐linked C*[n ]G dinucleoside 9 was synthesized by reductive amination of aldehyde 3 with an iminophosphorane derived from azide 7 . Deacylation of 9 gave the isopropylidene‐protected dinucleoside 10 . The sequence‐isomeric G*[n ]C dinucleoside 11 was similarly prepared from aldehyde 8 and azide 5 , and deacylated to 12 . The association of 10 and 12 in CHCl₃ or in CHCl₃/DMSO mixtures, and the structure of the associates were studied by ¹H‐NMR, ESI‐MS, CD, and vapor pressure osmometry (VPO). Broad ¹H‐NMR signals of dinucleosides 10 and 12 evidence an equilibrium between duplexes and quadruplexes (Hoogsteen base pairing between the Watson? Crick base‐paired duplexes). The quadruplex dominates for the G*[n ]C dinucleoside 12 between ?50° and room temperature. The sequence‐isomeric C*[n ]G 10 forms mostly only a cyclic duplex in CDCl₃ and in CDCl₃/(D₆)DMSO 9 : 1.     

PEG Grafted‐Nanodiamonds for the Delivery of Gemcitabine

Carboxyl end‐functionalized poly[poly(ethylene glycol) methyl ether methacrylate] [P(PEGMEMA)] and its block copolymer with gemcitabine substituted poly(N‐hydroxysuccinimide methacrylate) [PGem‐block‐P(PEGMEMA)] are synthesized via reversible addition‐fragmentation transfer (RAFT) polymerization. Then, two polymers are grafted onto the surface of amine‐functionalized nanodiamonds to obtain [P(PEGMEMA)]‐grafted nanodiamonds (ND‐PEG) and [PGem‐block‐P(PEGMEMA)]‐grafted nanodiamonds (ND‐PF). Gemcitabine is physically absorbed to ND‐PEG to produce ND‐PEG (Gem). Two polymer‐grafted nanodiamonds (i.e., with physically absorbed gemcitabine ND‐PEG (Gem) and with chemically conjugated gemcitabine ND‐PF) are characterized using attenuated total reflectance infrared spectroscopy, dynamic light scattering, and thermogravimetric analysis. The drug release, cytotoxicity (to seed human pancreatic carcinoma AsPC‐1 cells), and cellular uptake of ND‐PEG (Gem) and ND‐PF are also investigated.

     

Mass transfer examination in electrodialysis using limiting current measurements

The impact of electrodialysis module characteristics on mass transfer was examined using the limiting current method. The current-voltage curves of different electrodialysis modules were measured and limiting currents were determined using the derivative method. The mass transfer coefficients were calculated and the parameters of their dependence on linear flow velocity were estimated. From these the impact of spacer thickness, spacer net type, membrane type, and module geometry were evaluated. It was found that the impact of spacer thickness was almost negligible within the examined range, but a decrease in the mass transfer coefficient could be expected in the case of thicker spacers. By contrast, the spacer net type and type of membrane were found to be very important parameters able to significantly influence the mass transfer. By modifying the module geometry, the mass transfer coefficient could also be altered and, only in this case, the exponential parameter of the dependence was changing. The parameters thus determined may be used to calculate the limiting current in a wide range of operational conditions and may help predict the performance of different electrodialysis module types.