Mass spectrometric determination of ergosterol in a prairie natural wetland

Packed capillary liquid chromatography–electrospray mass spectrometry (LC–ESI-MS) was used for the analysis of a snow sample that was accidentally contaminated with an organophosphorus chemical warfare agent during the destruction of a chemical munition. Sarin, its hydrolysis products and a number of related compounds were identified on the basis of acquired LC–ESI-MS data. Full mass spectra were acquired for 14 compounds, with all exhibiting MH⁺, [MH+ACN]⁺ ions and/or protonated dimers that could be used to confirm molecular mass. Sampling cone voltages from 20 to 70 V were utilized with the higher sampling voltages enhancing formation of structurally important product ions in the ESI interface. All data were acquired with a time-of-flight mass spectrometer with a resolution of 5000 (50% valley definition), a resolution that aided in the assignment of elemental composition of the observed ions. The application of LC–ESI-MS to snow analysis appears to be an attractive alternative to the GC–MS methods, since both chemical warfare agents and their hydrolysis products may be analysed directly, eliminating the need for additional sample handling and derivatization steps.     

Single nanoparticle spectroscopy for real-time in vivo quantitative analysis of transport and toxicity of single nanoparticles in single embryos

Nanomaterials exhibit distinctive physicochemical properties and promise a wide range of applications from nanotechnology to nanomedicine, which raise serious concerns about their potential environmental impacts on ecosystems. Unlike any conventional chemicals, nanomaterials are highly heterogeneous, and their properties can alter over time. These unique characteristics underscore the importance of study of their properties and effects on living organisms in real time at single nanoparticle (NP) resolution. Here we report the development of single-NP plasmonic microscopy and spectroscopy (dark-field optical microscopy and spectroscopy, DFOMS) and ultrasensitive in vivo assay (cleavage-stage zebrafish embryos, critical aquatic species) to study transport and toxicity of single silver nanoparticles (Ag NPs, 95.4 ± 16.0 nm) on embryonic developments. We synthesized and characterized purified and stable (non-aggregation) Ag NPs, determined their sizes and doses (number), and their transport mechanisms and effects on embryonic development in vivo in real time at single-NP resolution. We found that single Ag NPs passively entered the embryos through their chorionic pores via random Brownian diffusion and stayed inside the embryos throughout their entire development (120 h), suggesting that the embryos can bio-concentrate trace NPs from their environment. Our studies show that higher doses and larger sizes of Ag NPs cause higher toxic effects on embryonic development, demonstrating that the embryos can serve as ultrasensitive in vivo assays to screen biocompatibility and toxicity of the NPs and monitor their potential release into aquatic ecosystems.     

Integration of functional myotubes with a Bio-MEMS device for non-invasive interrogation

We have developed a biological micro-electromechanical system (Bio-MEMS) device consisting of surface-modified microfabricated silicon cantilevers and an AFM detection apparatus for the study of cultured myotubes. With this system we are able to selectively stimulate the myotubes as well as report on a variety of physiological properties of the myotubes in real time and in a high-throughput manner. This system will serve as the foundation for future work integrating multiple tissue types for the creation of Bio-MEMS analogues of complex tissues and biological circuits.     

The Photochemical Isomerization Kinetics of Urocanic Acid and Their Effects upon the in vitro and in vivo Photoisomerization Action Spectra

Abstract— The kinetic rate equation for the photoreversible photoisomerization between trans -urocanic acid (UA) and cis-UA following absorption of UV radiation has been solved and used to show that the maximum of the trans -UA photoisomerization action spectrum depends upon both the initial trans -UA concentration irradiated in an experiment and upon the irradiation dose used to determine the amount of cis -UA generated. This kinetic model can be used to explain current discrepancies between in vitro and in vivo photoisomerization action spectra reported in the literature.     

The application of (Z)-3-aryl-3-haloenoic acids to the synthesis of (Z)-5-benzylidene-4-arylpyrrol-2(5H)-ones

Studies directed at the synthesis of (Z)-5-benzylidene-4-arylpyrrol-2(5H)-ones from (Z)-3-aryl-3-haloenoic acids are described. The successful strategy relies on the preparation of (Z)-3-aryl-3-haloenoic acids from acetophenones through the corresponding (Z)-3-aryl-3-haloenals and the conversion of the (Z)-3-aryl-3-haloenoic acids to (Z)-5-benzylidene-4-aryl-5H-furan-2-ones. The furanones were subsequently treated with primary amines and dehydrated to the corresponding (Z)-5-benzylidene-4-arylpyrrol-2(5H)-ones.     

Sodium paeoniflorin sulfonate, a process derived artefact from paeoniflorin

Sodium paeoniflorin sulfonate 2 was isolated from processed, but not unprocessed, Paeonia lactiflora roots and characterized by mass spectrometry and NMR spectroscopy. A notable and characteristic downfield shift in the ¹H NMR was observed for the hydrogens β to the alkoxysulfonate moiety in 2 and in other model compounds.     

Continuous‐Flow Oxidative Cyanation of Primary and Secondary Amines Using Singlet Oxygen

Primary and secondary amines can be rapidly and quantitatively oxidized to the corresponding imines by singlet oxygen. This reactive form of oxygen was produced using a variable‐temperature continuous‐flow LED‐photoreactor with a catalytic amount of tetraphenylporphyrin as the sensitizer. α‐Aminonitriles were obtained in good to excellent yields when trimethylsilyl cyanide served as an in situ imine trap. At 25°C, primary amines were found to undergo oxidative coupling prior to cyanide addition and yielded secondary α‐aminonitriles. Primary α‐aminonitriles were synthesized from the corresponding primary amines for the first time, by an oxidative Strecker reaction at –50 °C. This atom‐economic and protecting‐group‐free pathway provides a route to racemic amino acids, which was exemplified by the synthesis of tert‐leucine hydrochloride from neopentylamine.     

Reduction of nitric oxide by denitrifying bacteria

Two heterotrophic denitrifying bacteria,Paracoccus denitrificans andPseudomonas denitrificans, have been shown to utilize nitric oxide (NO) as a terminal electron acceptor and succinate, yeast extract, and heat/alkali pretreated municipal sewage sludge as carbon and energy sources. Complete removal of NO (0.50%) from a feed gas sparged into the cultures was observed. It is suggested that reduction of NO may be a common feature of denitrifying bacteria and that a microbial process to dispose of NO_x may be economically viable.     

Sequestration of naphthenic acids from aqueous solution using β-cyclodextrin-based polyurethanes

The sorption characteristics of naphthenic acids (NAs) in their anion form with β-cyclodextrin (β-CD) based polyurethanes, as sorbents, from aqueous solutions that simulate the conditions of oil sands process water (OSPW) are presented. The copolymer sorbents were synthesized at various β-CD:diisocyanate monomer mole ratios (e.g., 1:1, 1:2, and 1:3) with diisocyanates of variable molecular size and degree of unsaturation. The equilibrium sorption properties of the copolymer sorbents were characterized using sorption isotherms in aqueous solution at pH 9.00 with electrospray ionization mass spectrometry to monitor the equilibrium unbound fraction of anionic NAs in the aqueous phase. The copolymer sorbents were characterized in the solid state using (13)C CP-MAS NMR spectroscopy, IR spectroscopy and elemental analysis. The sorption results of the copolymer sorbents with anion forms of NAs in solution were compared with a commercially available carbonaceous standard: granular activated carbon (GAC). The monolayer sorption capacities of the sorbents (Q(m)) were obtained from either the Langmuir or the Sips isotherm model used to characterize the sorption characteristics of each copolymer sorbent. The estimated sorption capacity for GAC was 142 mg NAs per g sorbent whereas the polymeric materials ranged from 0-75 mg NAs per g sorbent over the experimental conditions investigated. In general, significant differences in the sorption capacities between GAC and the copolymer sorbents were related to the differences in the accessible surface areas and pore structure characteristics of the sorbents. The Sips parameter (K(eq)) for GAC and the copolymer materials reveal differences in the relative binding affinity of NAs to the sorbent framework in accordance with the synthetic ratios and the value of Q(m). The diisocyanate linker plays a secondary role in the sorption mechanism, whereas the β-CD macrocycle in the copolymer framework is the main sorption site for NAs because of the formation of inclusion complexes with β-CD.