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161.
Lavilla M Moros M Puertas S Grazú V Pérez MD Calvo M de la Fuente JM Sánchez L 《Analytical and bioanalytical chemistry》2012,402(10):3219-3226
Nowadays, the reference method for the detection of Clostridium tyrobutyricum in milk is the most-probable-number method, a very time-consuming and non-specific method. In this work, the suitability
of the use of superparamagnetic beads coated with specific antibodies and peptides for bioseparation and concentration of
spores of C. tyrobutyricum has been assessed. Peptide or antibody functionalized nanoparticles were able to specifically bind C. tyrobutyricum spores and concentrate them up to detectable levels. Moreover, several factors, such as particle size (200 nm and 1 μm),
particle derivatization (aminated and carboxylated beads), coating method, and type of ligand have been studied in order to
establish the most appropriate conditions for spore separation. Results show that concentration of spore is favored by a smaller
bead size due to the wider surface of interaction in relation to particle volume. Antibody orientation, related to the binding
method, is also critical in spore recovery. However, specific peptides seem to be a better ligand than antibodies, not only
due to the higher recovery ratio of spores obtained but also due to the prolonged stability over time, allowing an optimal
recovery of spores up to 3 weeks after bead coating. These results demonstrate that specific peptides bound to magnetic nanoparticles
can be used instead of traditional antibodies to specifically bind C. tyrobutyricum spores being a potential basis for a rapid method to detect this bacterial target. 相似文献
162.
163.
Sanna D Ugone V Micera G Garribba E 《Dalton transactions (Cambridge, England : 2003)》2012,41(24):7304-7318
The behaviour of the systems formed by VO(2+), 2-hydroxypyridine-N-oxide (Hhpo) and 2-mercaptopyridine-N-oxide (Hmpo) was studied both in solution and in the solid state through the combined application of spectroscopic (EPR and UV-Vis spectroscopy) and DFT methods. The geometry of solid bis-chelated complexes [VOL(2)], with L = hpo and mpo, is square pyramidal, but it can change to cis-[VOL(2)S], where S is a solvent molecule, when these are dissolved in a coordinating solvent. The equilibrium between the square pyramidal and cis-octahedral forms is strongly affected by solvent and temperature. At room temperature, the predominant species is [VOL(2)], which gives a pink colour to the solutions; at lower temperatures, the equilibrium is shifted--partially or completely--toward the formation of cis-[VOL(2)S], which is green. In an acidic environment and in the presence of an excess of ligand, [VOL(2)] can transform into the tris-chelated complex [VL(3)](+), in which vanadium loses the oxido ligand and adopts a hexa-coordinated geometry intermediate between octahedral and trigonal prismatic. 1-Methylimidazole (1-MeIm), which represents a model for His-N coordination, forms mixed complexes with stoichiometry cis-[VOL(2)(1-MeIm)], occupying an equatorial position. In the ternary systems VO(2+)-Hhpo-hTf and VO(2+)-Hmpo-hTf at room temperature and pH 7.4, besides (VO)hTf and (VO)(2)hTf, the mixed species cis-VO(hpo)(2)(hTf) and VO(mpo)(hTf) are observed, with the equatorial binding of an accessible histidine residue. Finally, the contribution of the N-oxide group to (51)V A(z) and A(iso) hyperfine coupling constants, which can be important in the characterisation of similar species, is discussed. 相似文献
164.
Matteo Passoni Valeria Russo David Dellasega Federica Causa Francesco Ghezzi Daniel Wolverson Carlo E. Bottani 《Journal of Raman spectroscopy : JRS》2012,43(7):884-888
An extensive Raman investigation of few‐layer graphene structures, obtained using a plasma microjet technique, is presented. Raman spectroscopy represents a unique method to characterize specific features of these systems. Excitation energies both in the visible and in the deep ultraviolet range are exploited, allowing to extract the main structural properties of the in‐house deposited samples. Particular attention is given to the determination of the stacking order properties of these few‐layer graphene structures. The results presented here also validate the plasma microjet as an efficient deposition technique to obtain graphene‐based systems with a low number of layers and reduced coupling on well defined and spatially localized areas. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
165.
V Castelletto IW Hamley C Stain C Connon 《Langmuir : the ACS journal of surfaces and colloids》2012,28(34):12575-12580
We report on the formation of hydrogel monoliths formed by functionalized peptide Fmoc-RGD (Fmoc: fluorenylmethoxycarbonyl) containing the RGD cell adhesion tripeptide motif. The monolith is stable in water for nearly 40 days. The gel monoliths present a rigid porous structure consisting of a network of peptide fibers. The RGD-decorated peptide fibers have a β-sheet secondary structure. We prove that Fmoc-RGD monoliths can be used to release and encapsulate material, including model hydrophilic dyes and drug compounds. We provide the first insight into the correlation between the absorption and release kinetics of this new material and show that both processes take place over similar time scales. 相似文献
166.
167.
Ptaquiloside (Pta) is a potent carcinogen present in bracken fern and in soil matrices, that can potentially leach to the aquatic environment. More recently its presence in the milk of different farm animals has been reported. Pterosin B (Ptb) and bromopterosin (BrPt) represent the most convenient analogues in the detection of ptaquiloside by mass spectrometry. Pterosin sesquiterpenes are also involved in many patented biomedical protocols. In this work we introduce a new and convenient approach to the synthesis in three steps and more than 80% yield of d?-pterosin B (d?-Ptb) and d?-bromopterosin (d?-BrPt), useful as internal standards in the quantification of ptaquiloside. 相似文献
168.
Jorge Yañez María Paz Farías Valeria Zúñiga César Soto David Contreras Eduardo Pereira Héctor D. Mansilla Renato Saavedra Rosario Castillo Pedro Sáez 《Microchemical Journal》2012
Conventionally, chemical patterns of gunshot residues (GSR) can be used for identification of a suspect involved in criminal fire arm incidents. Furthermore, metals composition in GSR is well related with the ammunition brand. In Chile the two main ammunition brands used are FAMAE and CBC. Metals, such as Pb, Ba, Sb, Cu, Zn and Ca are common elements detected in both brands. This work describes the application of both conventional and chemometric analysis of data (Regularized Discriminant Analysis, RDA) for differentiation of ammunition brands according to the metal patterns of GSR collected from shooter individuals. Real samples of GSR were collected from hands (dorsal region) of both shooters and non-shooters. Metals were analyzed using the techniques Atomic Absorption Spectrometry (AAS) and Inductively Coupled Plasma Atomic Emission Spectrometry (ICP-OES). By means of conventional plotting techniques for differentiation, such as binary and ternary plots, differences between the two brands are observed although without quantitative certainty. For the first time, applying chemometric analysis, such as regularized discriminant analysis (RDA), the investigated ammunition brands can be classified and differentiated correctly with 100% certainty. 相似文献
169.
Carmen Festa Simona De Marino Maria Valeria D’Auria Maria Chiara Monti Mariarosaria Bucci Valentina Vellecco Cécile Debitus Angela Zampella 《Tetrahedron》2012,68(13):2851-2857
DCCC chromatography followed by HPLC purification on the polar extract of marine sponge Theonella swinhoei resulted in the isolation of five new cyclopeptides, perthamides G–K. The new structures, featuring unprecedented amino acid units, were determined by interpretation of extensive spectroscopic and spectrometric data (MS, 1H and 13C NMR, COSY, HSQC, HMBC, and ROESY). Pharmacological analysis demonstrated that these natural cyclopeptides are endowed with anti-inflammatory potential as assessed by their ability to reduce carrageenan-induced mouse paw oedema. 相似文献
170.
V Azzarito P Prabhakaran AI Bartlett NS Murphy MJ Hardie CA Kilner TA Edwards SL Warriner AJ Wilson 《Organic & biomolecular chemistry》2012,10(32):6469-6472
The design and synthesis of a new 2-O-alklyated benzamide α-helix mimetic is described. Comparison with regioisomeric 3-O-alkylated benzamides permits a preliminary evaluation of the role that mimetic curvature has in determining molecular recognition properties. 相似文献