Gold(III) π-Allyl Complexes

Gold(III) π-complexes have been authenticated recently with alkenes, alkynes, and arenes. The key importance of Pd^II π-allyl complexes in organometallic chemistry (Tsuji–Trost reaction) prompted us to explore gold(III) π-allyl complexes, which have remained elusive so far. The (P,C)Au^III(allyl) and (methallyl) complexes 3 and 3′ were readily prepared and isolated as thermally and air-stable solids. Spectroscopic and crystallographic analyses combined with detailed DFT calculations support tight quasi-symmetric η³-coordination of the allyl moiety. The π-allyl gold(III) complexes are activated towards nucleophilic additions, as substantiated with β-diketo enolates.     

Evidence for Electron Transfer between Graphene and Non-Covalently Bound π-Systems

Hybridizing graphene and molecules possess a high potential for developing materials for new applications. However, new methods to characterize such hybrids must be developed. Herein, the wet-chemical non-covalent functionalization of graphene with cationic π-systems is presented and the interaction between graphene and the molecules is characterized in detail. A series of tricationic benzimidazolium salts with various steric demand and counterions was synthesized, characterized and used for the fabrication of graphene hybrids. Subsequently, the doping effects were studied. The molecules are adsorbed onto graphene and studied by Raman spectroscopy, XPS as well as ToF-SIMS. The charged π-systems show a p-doping effect on the underlying graphene. Consequently, the tricationic molecules are reduced through a partial electron transfer process from graphene, a process which is accompanied by the loss of counterions. DFT calculations support this hypothesis and the strong p-doping could be confirmed in fabricated monolayer graphene/hybrid FET devices. The results are the basis to develop sensor applications, which are based on analyte/molecule interactions and effects on doping.     

Treatment of Human Glioblastoma U251 Cells with Sulforaphane and a Peptide Nucleic Acid (PNA) Targeting miR-15b-5p: Synergistic Effects on Induction of Apoptosis

Glioblastoma multiforme (GBM) is a lethal malignant tumor accounting for 42% of the tumors of the central nervous system, the median survival being 15 months. At present, no curative treatment is available for GBM and new drugs and therapeutic protocols are urgently needed. In this context, combined therapy appears to be a very interesting approach. The isothiocyanate sulforaphane (SFN) has been previously shown to induce apoptosis and inhibit the growth and invasion of GBM cells. On the other hand, the microRNA miR-15b is involved in invasiveness and proliferation in GBM and its inhibition is associated with the induction of apoptosis. On the basis of these observations, the objective of the present study was to determine whether a combined treatment using SFN and a peptide nucleic acid interfering with miR-15b-5p (PNA-a15b) might be proposed for increasing the pro-apoptotic effects of the single agents. To verify this hypothesis, we have treated GMB U251 cells with SFN alone, PNA-a15b alone or their combination. The cell viability, apoptosis and combination index were, respectively, analyzed by calcein staining, annexin-V and caspase-3/7 assays, and RT-qPCR for genes involved in apoptosis. The efficacy of the PNA-a15b determined the miR-15b-5p content analyzed by RT-qPCR. The results obtained indicate that SFN and PNA-a15b synergistically act in inducing the apoptosis of U251 cells. Therefore, the PNA-a15b might be proposed in a “combo-therapy” associated with SFN. Overall, this study suggests the feasibility of using combined treatments based on PNAs targeting miRNA involved in GBM and nutraceuticals able to stimulate apoptosis.     

Glucose/Ribitol Dehydrogenase and 16.9 kDa Class I Heat Shock Protein 1 as Novel Wheat Allergens in Baker’s Respiratory Allergy

Wheat allergens are responsible for symptoms in 60–70% of bakers with work-related allergy, and knowledge, at the molecular level, of this disorder is progressively accumulating. The aim of the present study is to investigate the panel of wheat IgE positivity in allergic Italian bakers, evaluating a possible contribution of novel wheat allergens included in the water/salt soluble fraction. The water/salt-soluble wheat flour proteins from the Italian wheat cultivar Bolero were separated by using 1-DE and 2-DE gel electrophoresis. IgE-binding proteins were detected using the pooled sera of 26 wheat allergic bakers by immunoblotting and directly recognized in Coomassie stained gel. After a preparative electrophoretic step, two enriched fractions were furtherly separated in 2-DE allowing for detection, by Coomassie, of three different proteins in the range of 21–27 kDa that were recognized by the pooled baker’s IgE. Recovered spots were analyzed by nanoHPLC Chip tandem mass spectrometry (MS/MS). The immunodetected spots in 2D were subjected to mass spectrometry (MS) analysis identifying two new allergenic proteins: a glucose/ribitol dehydrogenase and a 16.9 kDa class I heat shock protein 1. Mass spectrometer testing of flour proteins of the wheat cultivars utilized by allergic bakers improves the identification of until now unknown occupational wheat allergens.     

Monthly Increase in Vitamin D Levels upon Supplementation with 2000 IU/Day in Healthy Volunteers: Result from “Integriamoci”, a Pilot Pharmacokinetic Study

Vitamin D (VD) is a calcium- and phosphate-controlling hormone used to treat bone disorders; yet, several other effects are progressively emerging. VD deficiency is highly prevalent worldwide, with suboptimal exposure to sunlight listed among the leading causes: oral supplementation with either cholecalciferol or calcitriol is used. However, there is a scarcity of clinical studies investigating how quickly VD concentrations can increase after supplementation. In this pilot study, the commercial supplement ImmuD3 (by Erboristeria Magentina^®) was chosen as the source of VD and 2000 IU/day was administered for one month to 21 healthy volunteers that had not taken any other VD supplements in the previous 30 days. Plasma VD levels were measured through liquid chromatography coupled to tandem mass spectrometry after 7, 14, and 28 days of supplementation. We found that 95% of the participants had insufficient VD levels at baseline (<30 ng/mL; median 23.72 ng/mL; IQR 18.10–26.15), but after 28 days of supplementation, this percentage dropped to 62% (median 28.35 ng/mL; IQR 25.78–35.20). The median increase in VD level was 3.09 ng/mL (IQR 1.60–5.68) after 7 days and 8.85 ng/mL (IQR 2.85–13.97F) after 28 days. This study suggests the need for continuing VD supplementation and for measuring target level attainment.     

General Method to Increase Carboxylic Acid Content on Nanodiamonds

Carboxylic acid is a commonly utilized functional group for covalent surface conjugation of carbon nanoparticles that is typically generated by acid oxidation. However, acid oxidation generates additional oxygen containing groups, including epoxides, ketones, aldehydes, lactones, and alcohols. We present a method to specifically enrich the carboxylic acid content on fluorescent nanodiamond (FND) surfaces. Lithium aluminum hydride is used to reduce oxygen containing surface groups to alcohols. The alcohols are then converted to carboxylic acids through a rhodium (II) acetate catalyzed carbene insertion reaction with tert–butyl diazoacetate and subsequent ester cleavage with trifluoroacetic acid. This carboxylic acid enrichment process significantly enhanced nanodiamond homogeneity and improved the efficiency of functionalizing the FND surface. Biotin functionalized fluorescent nanodiamonds were demonstrated to be robust and stable single-molecule fluorescence and optical trapping probes.     

Liquid chromatography tandem mass spectrometry determination of free and conjugated estrogens in breast cancer patients before and after exemestane treatment

We report liquid chromatographic separation with tandem mass spectrometry determination of 12 endogenous estrogens and their intact conjugates in blood and urine and its application to study effects of exemestane treatment on estrogen generation and metabolism in postmenopausal women with estrogen-dependent breast cancer. A 0.5 mL aliquot of each urine or serum sample is fractionated with solid phase extraction to a fraction of free estrogen and another fraction of their conjugates. The reversed phase LC/MS/MS determines dansylated estrogens with positive ionization and intact conjugates with negative ionization. The method provides reproducible separation and limit of detection as low as 1 pg mL⁻¹ for free estrogens and 0.03 ng mg⁻¹ creatinine for the conjugates in serum and urine samples. The method enabled us to acquire unique concentration profiles of 12 endogenous estrogens and their intact conjugates in 30 breast cancer patients before and after one month of exemestane treatment. Exemestane suppressed total serum and urinary estrogens by 11–97% (P < 0.0001) and 8.7–91% (P < 0.0001), respectively. Specifically, these data show that exemestane preferentially suppressed E1, E1-3S, E1-3G, and E2-17G more than other estrogens. Linear regression analysis of estrogen concentrations before and after treatment showed correlation coefficients of 0.8385 (n = 289, P < 0.0001) and 0.8863 (n = 360, P < 0.0001). This study provides urinary and blood estrogen concentration profiles in breast cancer patients to demonstrate the effect of exemestane on estrogen generation, supporting inhibition of aromatase activity.     

Polymicrobial Biofilm Inhibition Effects of Acetate‐Buffered Chitosan Sponge Delivery Device

Polymicrobial biofilm‐associated implant infections present a challenging clinical problem. Through modifications of lyophilized chitosan sponges, degradable drug delivery devices for antibiotic solution have been fabricated for prevention and treatment of contaminated musculoskeletal wounds. Elution of amikacin, vancomycin, or a combination of both follows a burst release pattern with vancomycin released above minimum inhibitory concentration for Staphylococcus aureus for 72 h and amikacin released above inhibitory concentrations for Pseudomonas aeruginosa for 3 h. Delivery of a vancomycin, amikacin, or a combination of both reduces biofilm formation on polytetrafluoroethylene catheters in an in vivo model of contamination. Release of dual antibiotics from sponges is more effective at preventing biofilm formation than single‐loaded chitosan sponges. Treatment of pre‐formed biofilm with high‐dose antibiotic release from chitosan sponges shows minimal reduction after 48 h. These results demonstrate infection‐preventive efficacy for antibiotic‐loaded sponges, as well as the need for modifications in the development of advanced materials to enhance treatment efficacy in removing established biofilm.

     

Tuning the Reactivity of Cyclopropenes from Living Ring‐Opening Metathesis Polymerization (ROMP) to Single‐Addition and Alternating ROMP

Ring‐opening metathesis polymerization (ROMP) has become one of the most important living polymerizations. Cyclopropenes (CPEs) remain underexplored for ROMP. Described here is that the simple swap of 1‐methyl to 1‐phenyl on 1‐(benzoyloxymethyl)CPEs elicited strikingly different modes of reactivity, switching from living polymerization to either selective single‐addition or living alternating ROMP. The distinct reactivity stems from differences in steric repulsions at the Ru alkylidene after CPE ring opening. Possible olefin or oxygen chelation from ring‐opened CPE substituents was also observed to significantly affect the rate of propagation. These results demonstrate the versatility of CPEs as a new class of monomers for ROMP, provide mechanistic insights for designing new monomers with rare single‐addition reactivity, and generate a new functionalizable alternating copolymer scaffold with controlled molecular weight and low dispersity.     

Buffers for the Physiological pH Range: Studies of 4-(N-Morpholino)butanesulfonic Acid (MOBS) from 5 to 55 °C

In this study, we report the pH values of two buffer solutions without chloride ion and eight buffer solutions with NaCl with an ionic strength I=0.16 mol?kg^?1. Electromotive force (emf) techniques have been used to get the cell potentials at 12 temperatures from 5 to 55?°C, including 37?°C. An extended form of the Bates-Guggenheim convention is used in the entire ionic strength range, 0.04 to 0.16?mol?kg^?1. The residual liquid junction potentials (??E _j ) of the buffer solutions of MOBS have been estimated from previous measurements with a flowing junction cell. These values of ??E _j have been used for correction in order to ascertain the operational pH values of four buffer solutions of MOBS at 25 and 37?°C. These solutions are recommended as pH standards for physiological application in the pH range 7.4 to 7.7.