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1.
Numerous biological processes are connected with the efficient electron transfer reactions in proteins and peptides. In this review, we discuss briefly the relevance and current challenges associated with the voltammetric analysis of peptides and proteins with and without a metal redox center. Special attention is paid to the integration of electrochemical methods with new nanomaterials which offers amplification of multiplexing capabilities for simultaneous and very sensitive examination of various proteins. After critically discussing the most interesting approaches in the proteins/peptides voltammetric analysis reported so far, for the single or multiplexed examination of such biomolecules with demonstrated applicability in the real-sample analysis, existing challenges still need to be addressed and future directions in this field will be pointed out. 相似文献
2.
Szklarzewicz Janusz Samotus Alina Nowicka Beata Burgess John Fawcett John Russell David R. 《Transition Metal Chemistry》1999,24(2):177-182
The X-ray crystal structure of (bpyH2)2[W(CN)8]·4H2 O (bpyH2=2,2-bipyridinium) is described. The [W(CN)8]4– anion has an approximately square antiprismatic (D4d) conformation, seemingly imposed by strong anion–water–cation hydrogen-bonding interactions. Bond distances in the anion are: WC 2.150(5), 2.163(5); CN 1.128(6), 1.145(6)Å and the angles WCN are 177.6(5), 178.3(5)°. The dihydrate and the anhydrous salt are both intensely black solids, exhibiting ion-pair charge-transfer interaction between cation and anion. E.s.r. spectra indicate that 30% of the tungsten is present as WV in the solid state, but that in solution only the WIV complex is present. The electron withdrawing effect of the cation is discussed and compared with that in a series of salts with different bipyridinium cations. 相似文献
3.
A simple model of adsorption of large macromolecules on ultra-fine colloidal particles is presented. The basic assumption of the model is that the number of particles attached to a single molecule is a random quantity. Both the reversible and irreversible polymerparticle binding is considered. Also, effects of the non-ideal mixing of polymer solution with suspension and of the polymer/particle size ratio on the shape of the adsorption isotherm are examined. The predictions of the model are confronted with experimental results of the study on the adsorption of very high molecular weight polyacrylamide on fine AgI colloidal particles. 相似文献
4.
We establish a new refinement of the right-hand side of the Hermite–Hadamard inequality for convex functions of several variables defined on simplices. 相似文献
5.
The aim of this study was to determine the effect of different drying methods: convective (at 50, 60, 70 °C), vacuum-microwave (at 120, 240, 360, 480 W and 360 W with reduction to 120 W) and hybrid (convective pre-drying at 50, 60, 70 °C followed by vacuum-microwave drying at 120 W) on the quality parameters of novel red-fleshed apple fruit snacks (RFAs), such as phenolics, on-line antioxidant capacity, water activity and color. Drying kinetics, including a temperature profile of dried material, and modified Page model were determined. Freeze-drying was used as a control method. The highest content of bioactive compounds in the samples was retained following freeze-drying, then hybrid, vacuum-microwave and finally convection drying. The antioxidant capacity measured by on-line 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt (ABTS), identified anthocyanins, flavan-3-ols and phenolic acid as the main compounds responsible for this activity. Unfavorable changes in color, formation of hydroxymethylfurfural (HMF) and degradation of polyphenolics were noted along with increasing drying temperature and magnetron power. The red-fleshed apple snacks are a promising high-quality dehydrated food product belonging to functional foods category. 相似文献
6.
Nowicka AM Zabost E Donten M Mazerska Z Stojek Z 《Analytical and bioanalytical chemistry》2007,389(6):1931-1940
A method is presented for the electroanalytical characterization of interactions of dsDNA with a drug, under conditions that
both agents are dissolved in the phosphate buffer solution and both are electroactive. Normal pulse, square wave, differential
pulse, and cyclic voltammetries were employed in the measurements of the drug and dsDNA oxidation signals at carbon electrodes.
UV–Vis spectroscopy was used as a non-electrochemical method to support the electroanalytical data. An anticancer drug, C-1311
(5-diethylaminoethyl-amino-8-hydroxyimidazoacridinone), has been selected for the examination. Normal pulse voltammetry was
particularly useful in showing that under the conditions employed neither dsDNA nor the drug were adsorbed at the electrode
surface. Necessary conditions for the appearance of the well-defined dsDNA voltammetric signal (guanine peak) are: rigorous
chemical and biological purity in the cell and appropriate purity of DNA. An analysis of the obtained results confirmed that
there were two modes of interaction between C-1311 and dsDNA: by intercalation and electrostatically. In the presence of excess
NaCl the electrostatic interactions deteriorate. The binding constants (K
1 and K
2, respectively) and the number (n) of nucleic base pairs (bp) and the number (m) of phosphate groups (pg) interacting with one molecule of drug have been determined. For strong interactions (intercalation)
the values of the binding constant, K
1, and the binding-site size, n, equal 3.7 × 104 M−1 and 2.1, respectively. For the weak electrostatic interactions the K
2 and m parameters equal 0.28 × 104 M−1 and 4.7. The intercalation process is rather slow and its rate (the conditions of pseudo-first-order reaction) was estimated
to equal 7 × 10−4 s−1. The possibility of independent determination of both interacting agents was very useful in the study.
Figure Intercalation of C-1311 into a dsDNA fragment 相似文献
7.
Two types of biomolecules were tested in the comparison of usefulness of two ways of formation of the intermediate layers at electrodes: a 20‐nucleotide DNA sequence and glucose oxidase. Chronocoulometric, amperometric, electrochemical impedance and PM‐IRRAS experiments proved that the layers obtained by electroreduction of diazonium salts are much more stable and more efficient in the accumulation of biomolecules compared to layers obtained by self‐assembling of appropriate thiols. 相似文献
8.
The mixing energy of two biphasic fluid systems (dispersions of two liquids or a liquid and a gas, A and B in a liquid C), confined between two parallel plates, is calculated. Our attention is limited to concentrated and monodisperse systems, i.e. emulsions and foam/emulsions consisting of equal-size (if of the same composition) cells separated by a thin liquid film. It is demonstrated that the multiphase mixtures ordered into regular patterns can be stable in a wide range of interfacial tensions acting along A-C and B-C interfaces and also in a wide range of volume fractions of fluid A. Anisotropic properties of such well-ordered structures are also demonstrated.Received: 8 December 2003, Published online: 4 May 2004PACS:
83.80.Iz Emulsions and foams - 05.65. + b Self-organized systems 相似文献
9.
Tomasz Rapecki Anna M. Nowicka Mikolaj Donten Fritz Scholz Zbigniew Stojek 《Electrochemistry communications》2010,12(11):1531-1534
GC electrodes were exposed to Fenton solutions. The surface changes produced by the OH? radicals of these solution were inspected using SEM, XPS, Raman spectroscopy and electrochemistry. The OH? radicals caused erosion and roughening of the surface, selective oxidation and dissolution of sp2 carbon, and reduction of the number of nucleation sites for silver deposition. 相似文献
10.
The standard molar enthalpies of solution at infinite dilution
\Updelta\textsol H\textm¥ \Updelta_{\text{sol}} H_{\text{m}}^{\infty } of glycylglycine, dl-alanyl-dl-alanine and glycylglycylglycine in aqueous solutions of potassium chloride and ethanol as well as of glycylglycine and glycylglycylglycine
in the solutions containing urea and water have been determined by calorimetry at the temperature 298.15 K. Changes of solution
enthalpy, expressed in a form so-called heterotactic interaction coefficients,
h\textxy h_{\text{xy}} were used for analysis of interactions occurring between the investigated solutes in water. The group contributions illustrating
the interactions of KCl, urea and ethanol with selected functional groups in the peptide molecules, namely CH2, “pep,” and “ion” groups, were calculated and discussed. 相似文献