Solid State Electrochemical Oxidation of Some Bisphosphoramidates in Aqueous Media and their Applications in DNA Sensing

Introduction of a thrombin sensor based on its interaction with dabigatran as an oral direct thrombin inhibitor

Dabigatran (DAB) is a direct thrombin inhibitor used for preventing blood clots and emboli after orthopedic surgery. The DAB - thrombin interaction was followed by fluorescence and UV-Vis spectroscopic methods. The binding of DAB to thrombin was also modeled by the molecular docking method. The obtained experimental results were consistent with theoretical results. The voltammetric method was also tested for DAB - thrombin interaction. Based on voltammetric findings, carbon paste electrode containing graphite powder, paraffin oil, MWCNTs, and DAB was constructed and used for thrombin monitoring after investigation of the DAB oxidation mechanism for the first time. The decrease in the linear sweep voltammetric (LSV) peak current of DAB in the presence of thrombin was utilized for the thrombin analysis. The calibration plot was linear in the concentration range of 1 to 70 nM (R² = 0.9992) by LSV technique with a detection limit of 0.3 nM. The applicability of the proposed sensor was evaluated by the determination of thrombin in human serum as a real sample.

A combined X-ray crystallography and theoretical study of N-H...OX (X is =P and -C) hydrogen bonds in two new structures with a (C-O)2(N)P(=Y) (Y is O and S) skeleton

The crystal structures of N,N'-(cyclohexane-1,4-diyl)bis(O,O'-diphenylphosphoramide), C₃₀H₃₂N₂O₆P₂ or (C₆H₅O)₂P(O)(1-NH)(C₆H₁₀)(4-NH)P(O)(OC₆H₅)₂, (I), and N,N'-(1,4-phenylene)bis(O,O'-dimethylthiophosphoramide), C₁₀H₁₈N₂O₄P₂S₂ or (CH₃O)₂P(S)(1-NH)(C₆H₄)(4-NH)P(S)(OCH₃)₂, (II), have been investigated. In the structure of (I), with an (O)₂(N)P(O) skeleton, two symmetry-independent phosphoramide molecules are linked through N-H...O=P hydrogen bonds. In the structure of (II), with an (O)₂(N)P(S) skeleton, the ester O atoms take part in N-H...O-C hydrogen bonds as acceptors; the P=S groups do not participate in hydrogen-bonding interactions. The strengths of these hydrogen bonds were evaluated, using quantum chemical calculations with the GAUSSIAN09 software package at the B3LYP/6-311G(d,p) level of theory. For this, LP(O) to σ*(NH) charge transfers were studied, according to the second-order perturbation theory in natural bond orbital (NBO) methodology, for a three-component cluster of hydrogen-bonded molecules for both structures, including all of the independent N-H...O hydrogen bonds observed in the crystal packing. The details of the intermolecular interactions were studied by Hirshfeld surface maps and two-dimensional fingerprint plots.