Bioelectrochemistry : human serum albumin-benzodiazepine binding

The binding of two benzodiazepines with Human Serum Albumin was studied by employing an A.C. polarographic method. The affinity constants and number of sites are reported in physiological conditions. Also thermodynamics parameters were calculated.The reproductibility of the method was good (CV = 2.1 %)

Interaction between glutathione and the basic nucleus of the B-lactam antibiotics : a bioelectrochemical study

An a.c. polarographic method is used to study the interaction between 6-aminopenicilanic acid and glutathione. Theoretical equations and the experimental results exhibit good correlation giving validity to the proposed method. The following interaction parameters were determined : coordination number p and interaction constant K. The interaction also was studied by an alternative U.V. method based on the spectral changes of the 6-Aminopenicilanic acid spectrogram in the presence of Glutathione. The K and p values obtained by both methods are non significantly different

Electrochemistry and XPS of 2,7-dinitro-9-fluorenone immobilized on multi-walled carbon nanotubes

We report that glassy carbon electrodes (GCE) modified with multi-walled carbon nanotubes (MWCNTs) can be derivatized with 2,7-dinitro-9-fluorenone (2,7-NFN). The derivatization procedure involves simple immersion of the MWCNT-modified electrode in a solution containing 2,7-NFN. SEM images indicate that the MWCNTs form a twisted, three-dimensional array that remains attached to the GCE surface. Both electrochemical and spectroscopic measurements (XPS) indicate that 2,7-NFN is immobilized on the electrode, most probably by being trapped within the pockets of the mentioned three-dimensional array. The electrode with the immobilized 2,7-NFN is sufficiently stable to resist washing but allows both its manipulation and reduction to form the hydroxylamine derivative. This derivative can be oxidized to form a nitroso compound. Both the nitroso and hydroxylamine derivatives are also trapped within the MWCNT surface pockets. Furthermore, depending on the selected working potential, the nature of the encapsulated compound, i.e., nitro, nitroso, or hydroxylamine derivative and mixtures thereof, can be selected. All these redox pathways were verified by cyclic voltammetry and XPS.Peer Reviewe

Interaction between glutathione and ampicillin : a microcalorimetric evidence

Direct reaction enthalpies between Glutathione and Ampicillin have determined by using a flow microcalorimeter.A microcalorimetric K value, 14.39 and a ΔH value, — 5.56 Kcal/mole, at physiological conditions of pH and temperature have been obtained.From the results, it is concluded that Glutathione reacts spontaneously with ampicillin, this process being exothermic at physiologic conditions of pH and temperature. Evidence of this interaction is highly important in order to permit the postulation of a new biotransformation route for this antibiotic

A simple derivatization of multiwalled carbon nanotubes with nitroaromatics in aqueous media: Modification with nitroso/hydroxylamine groups

We report that GCE modified with MWCNTs can be derivatized by the nitroaromatic drug nitrendipine (NTD) ((RS)-ethyl methyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate) simply by dipping the electrode in a solution of 0.1 M Britton–Robinson buffer containing 0.1 mM NTD (pH 2) for 4 min at open circuit. The derivatized electrode is thus reduced, producing the corresponding hydroxylamine derivative-modified electrode, which can be further oxidized to the nitroso derivative. A stable nitroso/hydroxylamine derivative couple appears if the modified electrode is conveniently cycled. With proper selection of the adequate potential, the derivatized electrode can be modified as nitroso or hydroxylamine derivatives. Keywords: Nitroaromatic modified electrode, MWCNT, Nitrendipine, Derivatizatio