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681.
Pepi F Ricci A Tata A Favero G Frasconi M Delle Noci S Mazzei F 《Chemical communications (Cambridge, England)》2007,(33):3494-3496
The present work illustrates a new method: soft landed protein voltammetry (SLPV); this experimental procedure is based on the coupling of ion soft landing with a voltammetric technique and allows the electrode surface to be functionalized with biologically active molecules, thus opening up numerous new perspectives ranging from molecular electronics to protein chips. 相似文献
682.
Scalas D Squadrone S Gili M Marchis D Prearo M Abete MC 《Journal of AOAC International》2007,90(5):1427-1431
A validation study was carried out in order to evaluate the performances of a dissociation enhanced lanthanide fluorescence immunoassay (DELFIA) for rapid screening of 17 beta-estradiol in bovine serum. This validation was performed according to European Union (EU) Decision 2002/657/EC, which establishes criteria and procedures for determination of detection capability (CCbeta), selectivity/specificity, and applicability/ruggedness/stability for qualitative screening tests. To determine these performance characteristics, 20 blank serum samples of cattle were collected and spiked with 17 beta-estradiol at 40 pg/mL, corresponding to the maximum residue limit permitted by Italian legislation. According to the EU Decision CCbeta criterion, spiked samples must have <5% probability to be classified as a false negative. 17 beta-Estradiol was detected in each spiked sample, and the CCbeta results were <40 pg/mL. There was also no observed interference effect due to chemically related substances or from the matrix. Moreover, slight variations of some critical factors in the DELFIA procedure, deliberately introduced for ruggedness evaluation, did not result in any negative effect on the 17beta-estradiol detection. The proposed method is suitable for qualitative screening analysis of 17 beta-estradiol according to EU performance requirements. 相似文献
683.
In this study, a RP-HPLC method for the analysis of polyacetylenes and polyenes in Echinacea pallida roots and phytopharmaceuticals was developed. The reference compounds used for quantification were isolated from the plant material and their structures were determined on the basis of the analysis of UV, IR, NMR and MS data. The complete structure elucidation of three compounds, namely 8-hydroxy-tetradec-(9E)-ene-11,13-diyn-2-one (1), tetradec-(8Z)-ene-11,13-diyn-2-one (6) and pentadec-(8Z)-en-2-one (9) is described. In the analysis of the n-hexane extracts of E. pallida roots, the comparison between conventional and monolithic columns showed that the elution order in both cases is identical and the selectivity is equivalent. However, the retention times achieved by the monolithic column are shorter, resulting in a faster separation (20 min). Therefore, the analyses were carried out on a Chromolith Performance RP-18e (100 mm x 4.6 mm i.d.), with a gradient mobile phase composed by H(2)O and ACN at the flow rate of 2 mL/min. The column was thermostatted at 20 degrees C. The photodiode array detector monitored the eluent at 210 nm. The validation procedure confirmed that this technique affords reliable analysis of these components and is appropriate for the quality control of complex matrices, such as E. pallida roots and phytopharmaceuticals. 相似文献
684.
The aim of this study was to produce Lantana camara essential oil by SFE and to study the effect of matrix grinding on the yield and/or composition of the extract. Experiments were carried out on grinding matrices (G) and on not grinding matrices (NG). The extracts were analyzed by GC-MS. A comparison with the oil obtained by hydrodistillation is also given. Finally, the antibacterial and antifungal activity of the various extracts has been assayed. 相似文献
685.
Abbruzzetti S Grandi E Bruno S Faggiano S Spyrakis F Mozzarelli A Cacciatori E Dominici P Viappiani C 《The journal of physical chemistry. B》2007,111(43):12582-12590
AHb1 is a hexacoordinated type 1 nonsymbiotic hemoglobin recently discovered in Arabidopsis thaliana. To gain insight into the ligand migration inside the protein, we studied the CO rebinding kinetics of AHb1 encapsulated in silica gels, in the presence of glycerol. The CO rebinding kinetics after nanosecond laser flash photolysis exhibits complex ligand migration patterns, consistent with the existence of discrete docking sites in which ligands can temporarily be stored before rebinding to the heme at different times. This finding may be of relevance to the physiological NO dioxygenase activity of this protein, which requires sequential binding of two substrates, NO and O2, to the heme. 相似文献
686.
Martinelli A Matic A Jacobsson P Börjesson L Fernicola A Panero S Scrosati B Ohno H 《The journal of physical chemistry. B》2007,111(43):12462-12467
We have investigated the physical properties of proton conducting polymer membranes based on a protic ionic liquid (IL). Properties such as ionic conductivity, melting point of the polymer phase, and glass transition temperature of the liquid phase are studied as a function of IL/polymer ratio and temperature. We observe an increased thermomechanical stability of the membrane with increasing polymer content. However, there is a concomitant decrease in the conductivity with increasing polymer content. This decrease is larger than what can be expected from the dilution of the conducting IL by the insulating polymer matrix. The origin of this decrease can be caused both by the morphology of the membrane and by interactions between the polymer matrix and the ionic liquid. We find a change in the glass transition temperature and in the temperature dependence of the conductivity with increasing polymer content. Both effects can be related to the physical confinement of the IL in the polymer membrane. 相似文献
687.
Di Giambattista L Pozzi D Grimaldi P Gaudenzi S Morrone S Castellano AC 《Analytical and bioanalytical chemistry》2011,399(8):2771-2778
Fourier transform infrared spectroscopy in attenuated total reflection can be used to discriminate the necrotic from the apoptotic
cell death in a tumoral T cell line irradiated by a UV source able to induce both apoptosis and necrosis. Using Jurkat cells
as the model system, significant spectral differences in the irradiated cells vs. time were observed in the lipid–proteins
ratio absorbance band at 1,397 cm−1 and in lactic acid IR band at 1,122 cm−1; these spectral features are inversely correlated with the percentage of apoptotic cells assessed by flow cytometry. From
the analysis of second derivatives in the IR spectral region between 1,800 and 900 cm−1, we have detected two significant spectral changes: the first centered at 1,621 cm−1 by analyzing the components of the amide I band and the second centered at 1,069 cm−1 due to C–O stretching vibration of the DNA backbone sensitive to the dehydrated state of DNA; these identified differences
in the intracellular biomolecules have been allowed to monitor the necrotic process. The variations in the spectral data set
have been identified by the Kruskal–Wallis test and confirmed by the hierarchical cluster analysis. 相似文献
688.
De Giglio E Trapani A Cafagna D Sabbatini L Cometa S 《Analytical and bioanalytical chemistry》2011,400(7):1997-2002
The formulation and characterization of dopamine (DA)-loaded chitosan nanoparticles (CSNPs) are described as preliminary steps
for the development of potential DA carrier systems intended for Parkinson’s disease treatment. For this purpose, CSNPs were
firstly produced and, afterwards, they were incubated in a DA aqueous solution to promote neurotransmitter loading. The characterization
of the resulting nanoparticles started with Fourier transform infrared spectroscopy analysis to ascertain the presence of
DA in the nanocarrier, whereas X-ray photoelectron spectroscopy analysis provided evidence of the localization of DA on the
nanoparticle surface. A quartz crystal microbalance with dissipation monitoring (QCM-D) was then exploited to investigate
both swelling of CSNPs and interaction of DA with CSNPs. In particular, the QCM-D revealed that this interaction is fast and
so this allows a stable nanostructured system to be obtained. 相似文献
689.
Dr. Matteo Amelia Stefania Impellizzeri Simone Monaco Dr. Ibrahim Yildiz Dr. Serena Silvi Prof. Françisco M. Raymo Prof. Alberto Credi 《Chemphyschem》2011,12(12):2280-2288
Two series of CdSe quantum dots (QDs) with different diameters are prepared, according to frequently used protocols of the same synthetic procedure. For each sample the photophysical properties and the potentials for the first reduction and oxidation processes in organic solution are determined. The band gap obtained from electrochemical experiments is compared with that determined from the absorption and luminescence spectra. While the optical band gap decreases upon increasing the nanocrystal diameter, as expected on the basis of quantum confinement, the redox potentials and the electrochemical band gap are not monotonously related to the QD size. For both series, the smallest and largest QDs are both easier to oxidize and reduce than mid‐sized QDs. In fact, the latter samples exhibit very broad voltammetric profiles, which suggests that the heterogeneous electron‐transfer processes from/to the electrode are kinetically hindered. Conversely, the electrochemical band gap for the smallest and largest particles of each series is somewhat smaller than the optical band gap. These results indicate that, while the optical band gap depends on the actual electron–hole recombination within the nanocrystal, and therefore follows the size dependence expected from the particle‐in‐a‐box model, the electrochemical processes of these QDs are strongly affected by other factors, such as the presence of surface defects. The investigations suggest that the influence of these defects on the potential values is more important for the smallest and largest QDs of each series, as confirmed by the respective luminescence bands and quantum yields. An interpretation for the size‐dependent evolution of the surface defects in these nanocrystals is proposed based on the mechanism of their formation and growth. 相似文献
690.
Daniela Coppola Stefano Bruno Luca Ronda Cristiano Viappiani Stefania Abbruzzetti Guido di Prisco Cinzia Verde Andrea Mozzarelli 《BMC biochemistry》2011,12(1):1-8