In this study, for the first time a model electrochemical kit was constructed for the detection of a functional polymorphism in catechol‐O‐methyl transferase (COMT) gene which is important for diagnosis of neuropsychiatric disorders as Alzheimer disease. The disposable pencil graphite electrode (PGE) is designed as a “kit” and the probe DNA covered PGE can detect single nucleotide polymorphisms (SNPs) from real samples based on the guanine oxidation signal even after 5 months of kit preparation (150 days durability).The detection limit (S/N=3) of the biosensor was calculated as 1.18 pmol of synthetic target sequence and 6.09×105 molecules of real samples in 30 min detection time. 相似文献
In this study graphite electrodes modified by a thin DNA‐imprinted polypyrrole layer, which was able to bind specific target‐DNA, are reported. For this aim, electrochemical synthesis of polypyrrole was performed on a pencil graphite electrode by cyclic voltammetry (CV) or by potential pulse sequences (PPS). The modified electrode surface was used for electrochemical determination of target‐DNA by differential pulse voltammetry. According to our best knowledge this is a first report on the application of DNA‐imprinted polymer for the determination of target‐DNA. The results showed that the molecularly imprinted polypyrrole (MIPPy) layer that formed on the carbon electrode surface was sensitive for target‐DNA, while the nonimprinted polypyrrole layer was not sensitive to the same target‐DNA. Comparison of electrodes modified using PPS and CV techniques is presented. 相似文献
A RP-LC method is presented, which is sensitive and selective for the simultaneous determination of enalapril–lercanidipine and enalapril–nitrendipine binary mixtures in their pharmaceutical dosage forms. The analyte peaks were detected using the LC method with the mobile phase ratio of methanol: water (70:30 v/v, pH 3.0) and a 1.0 mL min−1 flow rate. The detection wavelength was selected at 210 nm using photo diode array detector and column temperature was optimized to 30 °C. Linearity was obtained at different concentration ranges for all working pharmaceutically active compounds between 0.5 and 25 μg mL−1. The proposed methods were extensively validated according to USP 27 requirements and ICH guidelines. The methods were applied to the analysis of pharmaceutical dosage forms containing binary mixtures of enalapril–lercanidipine and enalapril–nitrendipine. Moreover, the proposed methods were applied for the degradation studies of the selected compounds. Degradation studies were conducted using stress conditions such as UV light, acidic and alkaline hydrolysis, oxidation and heat in oven, to evaluate the ability of the separation of the response of standard compounds from their degradation products.
We have obtained dihydrofurans 3a–j in the radical cyclization of 4‐hydroxycoumarin 1a and 2‐hydroxy‐1,4‐naphtoquinone 1b with electron rich alkenes 2a–i by manganese(III) acetate. Methods A and B, which have different molar ratios were studied comparatively in these reactions, and we observed that method B (molar ratio 2:1:3) gave the best results. Treatment of 4‐hydroxycoumarin 1a and electron rich alkenes 2a–e gave 2,3‐dihydro‐4H‐furo[3,2‐c]chromen‐4‐ones 3a–e in 36–86% yields by the method B. Under the same conditions, the reactions of 2‐hydroxy‐1,4‐naphtaquinone 1b with conjugated alkenes 2b and 2f–i afforded 2,3‐dihydronaphtho[2,3‐b]furan‐4,9‐diones 3f–j in an excellent yields. 相似文献
A series of β-amino alcohols derivatives were synthesized from (R)-2-amino-1-butanol and (S)-1,2-propanediol, and they have been used as organocatalaysts in the racemic ring opening of epoxide in good yields with high enantiomeric excess (up to 97%). 相似文献
In this study, the solid-state reaction mechanism and kinetics were investigated for production of anhydrous sodium metaborate (NaBO2), an industrially and technologically important boron compound. To assess the kinetics of solid-state production of NaBO2, the chemical reaction between borax (Na2B4O7) and sodium hydroxide (NaOH) was investigated by use of the thermal analysis techniques thermogravimetry (TG) and differential thermal analysis (DTA). DTA curves obtained under non-isothermal conditions at different heating rates (5, 10 and 20 °C/min), revealed five endothermic peaks corresponding to five solid-state reactions occurring at 70, 130, 295, 463, and 595 °C. The stages of the solid-state reaction used for production NaBO2 were also analyzed by XRD, which showed that at 70 and 130 °C, Na2B4O7 and NaOH particles contacted between the grains, and diffusion was initiated at the interface. However, there was not yet any observable formation of NaBO2. Formation of NaBO2 was initiated and sustained from 295 to 463 °C, and then completed at 595 °C; the product was anhydrous NaBO2. Activation energies (Ea) of the solid-state reactions were calculated from the weight loss based on the Arrhenius model; it was found that in the initial stages of the solid-state reaction Ea values were lower than in the last three steps. 相似文献
The nine new heteroaryl-substituted imidazolidinium (1a–c), pyrimidinium (2a–c) and diazepinium (3a–c) salts as N-heterocyclic carbene (NHC) precursors were synthesized in good yields and entirely characterized using elemental analyses and conventional spectroscopic methods. In situ formed complexes from heterocyclic salts (1–3), Pd(OAc)2 and in the presence of KOBut as a base were tested as catalysts for the Mizoroki–Heck coupling reaction in an aqueous media and very high yields were achieved. 1,3-Di(5-methylthiophen-2-ylmethyl)pyrimidinium hexafluorophosphate salt (2b) was structurally characterized by single-crystal X-ray diffraction. In the 2b compound (C16H21N2S2)+[PF6]?, the terminal thiophene rings are twisted with a dihedral angle of 72.8(3)°. In the pyrimidine ring, the three successive C atoms between the N atoms are disordered over two positions [occupancy ratio 0.753(12):0.247(12)]. In the crystal, neighboring molecules are linked by C–H…F hydrogen bonds, running along the b axis. 相似文献
The inhibition efficiency of 2-Pyrrolidin-1-yl-1,3-thiazole-5-carboxylic acid (PTCA) against mild steel (MS) corrosion was investigated in acidic solution by using quantum chemical calculations based on Density Functional Theory (DFT) method and electrochemical measurements. The electrochemical impedance spectroscopy (EIS), potentiodynamic, potential zero charge (pzc) analysis and electrochemical noise (EN) measurements at various concentrations (from 0.1 to 10 mM) and immersion times were utilized in experimental part. The surface analysis was achieved scanning electron microscope (SEM) and contact angle measurements in the absence and presence of 10 mM PTCA. According to DFT results, PTCA exhibited 3.737 eV band gap and 8.130 Debye dipole moment which were a signal of potentially convenient corrosion inhibitor properties. PTCA has a remarkable corrosion inhibition capability to mild steel, which inhibited both anodic and cathodic corrosion rates, relying on it's physically adsorption on the metal solution interface and protection ability was increased with increasing PTCA concentration. The obtained adsorption equilibrium constant was 11.11 × 103 M-1 and calculated standard free energy of adsorption was ?33.03 kJ mol?1. The determined activation energy values were 55.58 kJ mol?1 and 96.86 kJ mol?1 in 0.5 M HCl in the absence and presence of 10 mM PTCA, respectively. PTCA demonstrated a strong inhibition efficiency of 98.3%, after 168 h immersion, according to the EIS results. As a consequently, we recommend that PTCA is a convenient inhibitor in 0.1 M HCl for mild steel protection against corrosion. 相似文献