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881.
Determination of post-culture processing with carbohydrates by MALDI-MS and TMS derivatization GC-MS 总被引:1,自引:0,他引:1
Wunschel DS Wahl KL Melville AM Sorensen CM Colburn HA Valentine NB Stamper CL 《Talanta》2011,85(5):2352-2360
Biological materials generally require stabilization to retain activity or viability in a dry form. A number of industrial products, such as vaccines, probiotics and biopesticides have been produced as dry preparations. The same methods and materials used for stabilizing commercial microbial products may be applicable to preserving biothreat pathogens in a dry form. This is a likely step that may be encountered when looking at samples from terrorism attempts since only spores, such as those from Bacillus anthracis, are inherently stable when dried. The stabilizers for microbial preparations generally include one or more small carbohydrates. Different formulations have been reported for different industrial products and are often determined empirically. However sugar alcohols (mannitol and sorbitol) and disaccharides (lactose, sucrose and trehalose) are the common constituents of these formulations. We have developed an analytical method for sample preparation and detection of these simple carbohydrates using two complementary analytical tools, MALDI-MS and GC-MS. The native carbohydrates and other constituents of the formulation are detected by MALDI-MS as a screening tool. A longer and more detailed analysis is then used to specifically identify the carbohydrates by derivatization and GC-MS detection. Both techniques were tested against ten different types of stabilization recipes with Yersinia pestis cell mass cultured on different media types used as the biological component. A number of additional components were included in these formulations including proteins and peptides from serum or milk, polymers (e.g. poly vinyl pyrrolidone - PVP) and detergents (e.g. Tween). The combined method was characterized to determine several figures of merit. The accuracy of the method was 98% for MALDI-MS and 100% for GC-MS. The repeatability for detection of carbohydrates by MALDI-MS was determined to be 96%. The repeatability of compound identification by GC-MS was determined by monitoring variation in retention time, which is vital for identification of isomeric carbohydrates. The figures of merit illustrate an effective and accurate method for mono and disaccharide detection independent of formulation. This meets our primary goal for method development as small carbohydrates are among the most common stabilizers employed. 相似文献
882.
Lam M Jou PC Lattif AA Lee Y Malbasa CL Mukherjee PK Oleinick NL Ghannoum MA Cooper KD Baron ED 《Photochemistry and photobiology》2011,87(4):904-909
The high prevalence of drug resistance necessitates the development of novel antifungal agents against infections caused by opportunistic fungal pathogens, such as Candida albicans. Elucidation of apoptosis in yeast-like fungi may provide a basis for future therapies. In mammalian cells, photodynamic therapy (PDT) has been demonstrated to generate reactive oxygen species, leading to immediate oxidative modifications of biological molecules and resulting in apoptotic cell death. In this report, we assess the in vitro cytotoxicity and mechanism of PDT, using the photosensitizer Pc 4, in planktonic C. albicans. Confocal image analysis confirmed that Pc 4 localizes to cytosolic organelles, including mitochondria. A colony formation assay showed that 1.0 μM Pc 4 followed by light at 2.0 J cm(-2) reduced cell survival by 4 logs. XTT (2,3-bis[2-methoxy-4-nitro-5-sulfophenyl]-2H-tetrazolium-5-carboxyanilide) assay revealed that Pc 4-PDT impaired fungal metabolic activity, which was confirmed using the FUN-1 (2-chloro-4-[2,3-dihydro-3-methyl-(benzo-1,3-thiazol-2-yl)-methylidene]-1-phenylquinolinium iodide) fluorescence probe. Furthermore, we observed changes in nuclear morphology characteristic of apoptosis, which were substantiated by increased externalization of phosphatidylserine and DNA fragmentation following Pc 4-PDT. These data indicate that Pc 4-PDT can induce apoptosis in C. albicans. Therefore, a better understanding of the process will be helpful, as PDT may become a useful treatment option for candidiasis. 相似文献
883.
Parker LJ Italiano LC Morton CJ Hancock NC Ascher DB Aitken JB Harris HH Campomanes P Rothlisberger U De Luca A Lo Bello M Ang WH Dyson PJ Parker MW 《Chemistry (Weinheim an der Bergstrasse, Germany)》2011,17(28):7806-7816
Platinum-based cancer drugs, such as cisplatin, are highly effective chemotherapeutic agents used extensively for the treatment of solid tumors. However, their effectiveness is limited by drug resistance, which, in some cancers, has been associated with an overexpression of pi class glutathione S-transferase (GST P1-1), an important enzyme in the mercapturic acid detoxification pathway. Ethacraplatin (EA-CPT), a trans-Pt(IV) carboxylate complex containing ethacrynate ligands, was designed as a platinum cancer metallodrug that could also target cytosolic GST enzymes. We previously reported that EA-CPT was an excellent inhibitor of GST activity in live mammalian cells compared to either cisplatin or ethacrynic acid. In order to understand the nature of the drug-protein interactions between EA-CPT and GST P1-1, and to obtain mechanistic insights at a molecular level, structural and biochemical investigations were carried out, supported by molecular modeling analysis using quantum mechanical/molecular mechanical methods. The results suggest that EA-CPT preferentially docks at the dimer interface at GST P1-1 and subsequent interaction with the enzyme resulted in docking of the ethacrynate ligands at both active sites (in the H-sites), with the Pt moiety remaining bound at the dimer interface. The activation of the inhibitor by its target enzyme and covalent binding accounts for the strong and irreversible inhibition of enzymatic activity by the platinum complex. 相似文献
884.
DNA methylation analysis is emerging as a new technique with potential capabilities for early cancer detection. However, current state-of-the-art techniques are not easily translatable into routine clinical methods. Herein we describe a bead-based flow cytometry assay which combines DNA hybridization to microparticles with 5MeC-specific proteins/antibodies. These assays can be used to study the binding properties of current and emerging 5MeC-binding proteins and may also have potential in the measurement of 5MeC density in clinical samples for cancer detection. 相似文献
885.
Nancy K. Umisedo Elisabeth M. Yoshimura Patricia B.R. Gasparian E.G. Yukihara 《Radiation measurements》2010,45(2):151-156
This paper presents a systematic comparison of OSL signals from Al2O3:C when stimulated with blue and green light. Al2O3:C detectors were irradiated with various doses and submitted to various bleaching regimes using yellow, green and blue light. Most of the investigations were carried out using Luxel?-type detectors used in the commercial Luxel? and InLight? dosimetry systems (Landauer Inc.). Al2O3:C single crystals and Al2O3:C powder were also used to complement the investigations. The results show that, although blue stimulation provides faster readout times (OSL curves that decayed faster) and higher initial OSL intensity than green stimulation, blue stimulation introduced complicating factors. These include incomplete bleaching of the dosimetric trap when the Al2O3:C detectors are bleached with yellow or green light and the OSL is recorded with blue light stimulation, and an increased residual level due to stimulation of charge carriers from deep traps. The results warrant caution when using blue stimulation to measure the OSL signal from Al2O3:C detectors, particularly if the doses involved are low and the detectors have been previously exposed to high doses. 相似文献
886.
Marcelo M. Campos‐Vallette Nancy P. Chandía Ernesto Clavijo David Leal Betty Matsuhiro Igor O. Osorio‐Romn Simonet Torres 《Journal of Raman spectroscopy : JRS》2010,41(7):758-763
The surface‐enhanced Raman scattering (SERS) of sodium alginates and their hetero‐ and homopolymeric fractions obtained from four seaweeds of the Chilean coast was studied. Alginic acid is a copolymer of β‐D ‐mannuronic acid (M) and α‐L guluronic acid (G), linked 1 → 4, forming two homopolymeric fractions (MM and GG) and a heteropolymeric fraction (MG). The SERS spectra were registered on silver colloid with the 632.8 nm line of a He Ne laser. The SERS spectra of sodium alginate and the polyguluronate fraction present various carboxylate bands which are probably due to the coexistence of different molecular conformations. SERS allows to differentiate the hetero‐ and homopolymeric fractions of alginic acid by characteristic bands. In the fingerprint region, all the poly‐D ‐mannuronate samples present a band around 946 cm−1 assigned to C O stretching, and C C H and C O H deformation vibrations, a band at 863 cm−1 assigned to deformation vibration of β‐C1 H group, and one at 799–788 cm−1 due to the contributions of various vibration modes. Poly‐L ‐guluronate spectra show three characteristic bands, at 928–913 cm−1 assigned to symmetric stretching vibration of C O C group, at 890–889 cm−1 due to C C H, skeletal C C, and C O vibrations, and at 797 cm−1 assigned to α C1 H deformation vibration. The heteropolymeric fractions present two characteristic bands in the region with the more important one being an intense band at 730 cm−1 due to ring breathing vibration mode. Copyright © 2009 John Wiley & Sons, Ltd. 相似文献
887.
Gurleen Singh Nancy George Riddima Singh Gurjaspreet Singh Sushma Gurpreet Kaur Harminder Singh Jandeep Singh 《应用有机金属化学》2023,37(1):e6897
1,2,3-Triazole-based ligands obtained through copper(I)-catalyzed azide-alkyne cycloaddition (CuAAC) have been exploited in vast array of research domains owing to the stitching of simpler molecules through a needle of Cu(I) catalyst. The numerous reports on ion(s) detection capabilities of synthesized 1,4-disubstituted 1,2,3-triazole ligands using absorption and fluorescence spectroscopy are accessible. This review enlists substituted 1,2,3-triazole-based sensor probes, since 2010, synthesized selectively by CuAAC, having the ability to sense either a single ion or multiple ions under specific set of conditions along with their detection limits. The review also apprehends the different techniques and sensing mechanisms involved in the detection of ions by chemosensor probes. 相似文献
888.
Kyoung Chul Park Prof. Dr. Preecha Kittikhunnatham Dr. Jaewoong Lim Grace C. Thaggard Yuan Liu Dr. Corey R. Martin Dr. Gabrielle A. Leith Donald J. Toler Dr. An T. Ta Dr. Nancy Birkner Dr. Ingrid Lehman-Andino Dr. Alejandra Hernandez-Jimenez Dr. Gregory Morrison Dr. Jake W. Amoroso Prof. Dr. Hans-Conrad zur Loye Dr. Dave P. DiPrete Dr. Mark D. Smith Prof. Dr. Kyle S. Brinkman Prof. Dr. Simon R. Phillpot Prof. Dr. Natalia B. Shustova 《Angewandte Chemie (International ed. in English)》2023,62(5):e202216349
A novel series of heterometallic f-block-frameworks including the first examples of transuranic heterometallic 238U/239Pu-metal–organic frameworks (MOFs) and a novel monometallic 239Pu-analog are reported. In combination with theoretical calculations, we probed the kinetics and thermodynamics of heterometallic actinide(An)-MOF formation and reported the first value of a U-to-Th transmetallation rate. We concluded that formation of uranyl species could be a driving force for solid-state metathesis. Density of states near the Fermi edge, enthalpy of formation, band gap, proton affinity, and thermal/chemical stability were probed as a function of metal ratios. Furthermore, we achieved 97 % of the theoretical maximum capacity for An-integration. These studies shed light on fundamental aspects of actinide chemistry and also foreshadow avenues for the development of emerging classes of An-containing materials, including radioisotope thermoelectric generators or metalloradiopharmaceuticals. 相似文献
889.
Dr. Biao Jin Ying Chen Jinhui Tao Dr. Kacper J. Lachowski Mark E. Bowden Zihao Zhang Dr. Lilo D. Pozzo Nancy M. Washton Karl T. Mueller James J. De Yoreo 《Angewandte Chemie (International ed. in English)》2023,62(28):e202303770
Hierarchical nucleation pathways are ubiquitous in the synthesis of minerals and materials. In the case of zeolites and metal–organic frameworks, pre-organized multi-ion “secondary building units” (SBUs) have been proposed as fundamental building blocks. However, detailing the progress of multi-step reaction mechanisms from monomeric species to stable crystals and defining the structures of the SBUs remains an unmet challenge. Combining in situ nuclear magnetic resonance, small-angle X-ray scattering, and atomic force microscopy, we show that crystallization of the framework silicate, cyclosilicate hydrate, occurs through an assembly of cubic octameric Q38 polyanions formed through cross-linking and polymerization of smaller silicate monomers and other oligomers. These Q38 are stabilized by hydrogen bonds with surrounding H2O and tetramethylammonium ions (TMA+). When Q38 levels reach a threshold of ≈32 % of the total silicate species, nucleation occurs. Further growth proceeds through the incorporation of [(TMA)x(Q38)⋅n H2O](x−8) clathrate complexes into step edges on the crystals. 相似文献
890.