[en] The method of e-beam excitation is used to study the chemiluminescence of luminol and the related compound 5-hydroxy-2,3-dihyrdro-1,4-phthalazindione. Absolute yields of chemiluminescence are determined and the factors contributing to the yields observed are analyzed. Direct observation of the immediate precursor of the emitting molecule allows determination of its chemical yield. This is found to be about 10% for both systems studied. The other main cause for the low overall yield is the poor fluorescence efficiency. On the other hand, the step leading from the precursor to the emitting molecule, is found to be highly efficient and selective. These results are compared with those obtained by the conventional luminol-H₂O₂ reaction. (Auth.)

[en] Some new derivatives of 3-amino-1-aryl-N-butyl-5,10-dioxo-5,10-dihydro-1H-pyrazolo[1,2-b]- phthalazine-2-carboxamide are synthesized via in situ Knoevenagel condensation of aromatic aldehydes with N-butyl-2-cyanoacetamide, which leads to 3-aryl-N-butyl-2-cyanoacrylamides. This is followed by the reaction with phthalhydrazide upon refluxing in ethanol under catalyst-free conditions. The products are characterized on the basis of IR, ¹H and ¹³C NMR spectral data.

[en] Nanostructured CuO was successfully utilized for the synthesis of 1H-pyrazolo[1,2-b]phthalazine-5,10-dione derivatives via one-pot multicomponent reaction among phthalhydrazide, malononitrile and aromatic aldehydes under solvent-free conditions. Utilization of non-toxic and inexpensive catalyst, improved yields in short reaction times, wide substrate scope and easy purification of products are the important features of the developed protocol. The CuO nanocatalyst presents good reusability over five catalytic cycles.

[en] A retrospective analysis was performed to investigate the radioprotective effects of azelastine against radiation dermatitis for patients with head and neck cancers. The effects of azelastine were studied in 19 patients with laryngeal cancers treated by irradiation. As controls, 29 patients with laryngeal cancers treated by irradiation without the administration of azelastine were studied. All patients were irradiated using 3 MV linac X-rays. Azelastine was administered orally twice a day. Moist desquamation was observed in four of 29 control patients whereas no such moist desquamation developed after the administration of azelastine. Two cases of moist desquamation that developed before the administration of azelastine regressed during irradiation in patients placed on azelastine. Radiotherapy was completed without interruption in all patients treated with azelastine. No severe side effects were observed. Azelastine, administered orally, was a safe drug and has the potential of improving skin tolerance in irradiation therapy. (author)

[en] A kind of biocatalyst, laccase, has been employed as a biocompatible coreactant accelerator to efficiently catalyze coreactant (dissolved O₂) for generating high local concentration of superoxide radical (O₂^•−), acquiring high-intense electrochemiluminescence (ECL) emission of ABEI (N-(aminobutyl)-N-(ethylisoluminol))/dissolved O₂ system. Furthermore, a modified strand displacement reaction with excellent amplification efficiency was constructed by replacing traditional single strand DNA to the hairpin DNA as template for triggering the immobilization of more signal probes. As a result, the biosensor for microRNA-21 determination has preeminent selectivity and favorable sensitivity with detection limit down to 80.8 aM. Significantly, the devised strategy has blazed a new path for seeking more coreaction accelerators with splendid biocompatibility thus promoting the application of ternary ECL systems in biological analysis and clinical diagnosis. Graphical abstract:

No abstract available

[en] A novel electrochemiluminescence (ECL) biosensor for the determination of microRNA-21 (miRNA-21) was developed, based on a hybrid luminescent Co-MOF-ABEI/Ti₃C₂T_x composite as an ECL luminophore combined with a duplex-specific nuclease (DSN)-assisted signal amplification strategy. The synthesized Co-MOF-ABEI/Ti₃C₂T_x composite carrying N-(4-aminobutyl)-N-ethylisoluminol (ABEI) exhibited strong and stable ECL in the presence of reactive oxygen species (ROS). The ECL biosensor was fabricated by adsorbing Co-MOF-ABEI/Ti₃C₂T_x onto a glassy carbon electrode and covalently coupling the probe DNA onto the surface of the Co-MOF-ABEI/Ti₃C₂T_x-modified electrode. In the presence of the target miRNA-21, the DSN selectively cleaved the complementary DNA section (S1) to miRNA-21, resulting in the release of the transduction section (S2) and the reuse of miRNA-21 in the subsequent amplification cycle. The interaction of the stem-loop structure of the probe DNA with the Co-MOF-ABEI/Ti₃C₂T_x-modified glassy carbon electrode with S2 strands led to the opening of the annular part of the probe DNA. Then, the opened guanine (G)-rich sequences of probe DNA were exposed and folded into a hemin/G-quadruplex DNAzyme in the presence of hemin. The catalysis of H₂O₂ to ROS by the hemin/G-quadruplex DNAzyme significantly enhanced ECL intensity, and this intensity was logarithmically proportional to the concentration of target miRNA-21 between 0.00001 and 10 nM, having a limit of detection of 3.7 fM. The designed ECL biosensor can detect miRNA-21 extracted from HeLa cells, indicating its promising application in clinical diagnosis and disease prognosis analysis.

[en] The interaction of DNA molecule with new synthetic compounds, piperazine derivatives of benzo[4,5]imidazo[1,2-a]phthalazine, was investigated by the spectral, hydrodynamic and optical methods. The thermodynamic parameters of the interaction and the stoichiometry of the complexes were determined by spectrophotometric titration. A mode of binding and structure of the complexes were determined by analyzing the changes in the intrinsic viscosity and the optical anisotropy of the macromolecule upon complexation. It is shown that an increase in the intrinsic viscosity and the optical anisotropy with a small content of the ligand in the complex is caused by the increase in the thermodynamic rigidity of macromolecules upon the formation of the complex. Increase of the contour length of the macromolecule in the complex does not occur, that indicates nonintercalative mode of binding the piperazine derivatives of benzoimidazophthalazine with DNA. (paper)

[en] The molecular and crystal structure of 4-ethoxycarbonyloxy-1-oxo-1H-phthalazine 2-carboxylic acid ethyl ester has been elucidated by X-ray diffraction methods. The compound crystallizes in the orthorhombic crystal system (space group Pc) with the unit cell parameters a = 10.758(9), b = 4.631(3), c = 14.957(7) A, β = 107.30(6) deg. and Z = 2. The structure has been solved by direct methods and refined to a final R value of 0.060 for 870 observed reflections [F_o > 4σ(F_o)]. The presence of a large number of intra-and intermolecular interactions makes the molecule look like a four-ring structure. The structure is stabilized by C-H...O hydrogen bonds

[en] 1-[¹⁴C] Hydroxymethyl-6-ethoxycarbonyl-5,7-dimethyl-4-phthalazone ([¹⁴C] EG-626) was synthesised from 6-ethoxy-carbonyl-5,7-dimethyl-4-methoxyphthalazine-2-N-oxide and potassium [¹⁴C] cyanide by the Reissert-Henze reaction. The overall radiochemical yield from potassium [¹⁴C] cyanide was 21.0 %. (author)