Combination of polymer and halloysite chemistry for development of a novel catalytic hybrid system

Research on Chemical Intermediates - A covalent hybrid of halloysite-poly(methyl methacrylate-co-maleic anhydride) was prepared and applied for the immobilization of Pd nanoparticles. The hybrid...     

A spectrophotometric and thermodynamic study of the charge-transfer complexes of iodine with nortriptyline and imipramine drugs in chloroform and dichloromethane solutions

The interaction of iodine as electron acceptor with nortriptyline and imipramine drugs as electron donors has been investigated spectrophotometrically at various temperatures in chloroform and dichloromethane solutions. The observed time dependence of the charge–transfer band and subsequent formation of in solution were related to the slow transformation of the initially formed iodine: drug outer complex to an inner electron donor–acceptor (EDA) complex, followed by fast reaction of the inner complex with iodine to form a triiodide ion. The pseudo-first-order rate constants and activation parameters for the transformation process were evaluated from the absorbance-time data. Stoichiometrices of the complexes were defined by the Job’s method of the continuos variation and obtaind 2: 1 for iodine: drug complexes. The formation constants and molar absorptivities were evaluated from the absorbance-mole ratio data. Thermodynamic parameters of the complexes have been determined from the temperature dependence of the stability constant by Van’t Hoff equation.     

Synthesis,characterization, cytotoxic activity and DNA-binding studies of cobalt (II) mixed-ligand complex containing pyridine-2,6-dicarboxylate ion and 2-aminopyrimidine

Treatment of pyridine-2,6-dicarboxylic acid and 2-aminopyrimidine with Co(NO₃)₂?6H₂O under hydrothermal conditions led to a new Co (II) complex [Co(amp)(pydc)(H₂O)₂]?H₂O (1), which was characterized by infrared spectroscopy, elemental analysis as well as X-ray diffraction studies. The DNA-binding behavior of the complex has been studied by UV–Vis absorption and fluorescence spectroscopic titration, viscosity measurements, thermal denaturation and circular dichroism (CD). The experimental results indicated that Co (II) complex was bound to DNA by an intercalative mode. The intrinsic binding constant of Co (II) complex with DNA was (3.80 ± 0.02) × 10⁴ M^?1. The biological effects of the Co (II) complex were also studied by MTT assay in MCF-7 and HT-29 cancer cell lines. Treatment of MCF-7 and HT-29 cells with Co (II) complex resulted in a concentration-dependent cell growth inhibition.     

Biomimetic Sensor for Dobutamine Employing Nano‐ TiO2/Nafion/Carbon Nanoparticles Modified Electrode

A novel voltammetric biosensor based on nano‐TiO₂/nafion/carbon nanoparticles modified glassy carbon electrode (TiO₂/N/CNP/GCE) was developed for the determination of dobutamine (DBA). Characterization of the surface morphology and property of TiO₂/N/CNP layer was carried out by the scanning electron microscopy and atomic force microscopy. The electrochemical performance of the modified electrode was investigated by means of the cyclic voltammetry, differential pulse voltammetry and electrochemical impedance spectroscopy techniques. Effective experimental variables, such as the scan rate, pH of the supporting electrolyte, drop size of the casted modifier suspension and accumulation conditions of DBA on the surface of TiO₂/N/CNP/GCE were optimized. Under the optimized conditions, a significant electrochemical improvement was observed toward the electro‐oxidation of DBA on the surface of TiO₂/N/CNP/GCE compared to the bare GCE. Under the optimized conditions, a wide linear dynamic range (6 nM–1 µM) with a low detection limit of 2 nM for DBA was resulted. The prepared modified electrode shows high sensitivity, stability and good reproducibility in the determination of DBA concentrations. Satisfactory results were obtained for DBA analysis in the pharmaceutical and clinical preparations using TiO₂/N/CNP/GCE.     

Quantitative Point of Care Tests for Timely Diagnosis of Early-Onset Preeclampsia with High Sensitivity and Specificity

Preeclampsia is a heterogeneous and multiorgan cardiovascular disorder of pregnancy. Here, we report the development of a novel strip-based lateral flow assay (LFA) using lanthanide-doped upconversion nanoparticles conjugated to antibodies targeting two different biomarkers for detection of preeclampsia. We first measured circulating plasma FKBPL and CD44 protein concentrations from individuals with early-onset preeclampsia (EOPE), using ELISA. We confirmed that the CD44/FKBPL ratio is reduced in EOPE with a good diagnostic potential. Using our rapid LFA prototypes, we achieved an improved lower limit of detection: 10 pg ml⁻¹ for FKBPL and 15 pg ml⁻¹ for CD44, which is more than one order lower than the standard ELISA method. Using clinical samples, a cut-off value of 1.24 for CD44/FKBPL ratio provided positive predictive value of 100 % and the negative predictive value of 91 %. Our LFA shows promise as a rapid and highly sensitive point-of-care test for preeclampsia.     

Evaluation of feed-forward back propagation and radial basis function neural networks in simultaneous kinetic spectrophotometric determination of nitroaniline isomers

Mixtures of 2-, 3-, and 4-nitoroanilines, are simultaneously analyzed with spectrophotometry, based on their different kinetic properties. These nitroanilines react differentially with 1,2-naphtoquinone-4-sulphonate (NQS) at pH 7 in micellar medium to produce colored product. The differential kinetic spectra were monitored and recorded at 500 nm, and the data obtained from the experiments were processed by chemometric approaches, such as back-propagation neural networks (BPNNs), radial basis function neural networks (RBFNNs), and partial least squares (PLS). Experimental conditions were optimized and training the network was performed using principal components (PCs) of the original data. A set of synthetic mixtures of nitroanilines was evaluated and the results obtained by the application of these chemometric approaches were discussed and compared. The analytical performance of the models was characterized by relative standard errors. It was found that the artificial neural networks model affords relatively better results than PLS. The proposed method was applied to the determination of considered nitroanilines in water samples.     

γ‐Fe2O3@Cu3Al‐LDH‐TUD as a new Amphoteric,Highly Efficient and Recyclable Heterogeneous Catalyst for the Solvent‐free Synthesis of Dihydropyrano[3,2‐c]pyrazoles and dihydropyrano[3,2‐c]chromens

Thiourea dioxide was immobilized on γ‐Fe₂O₃@Cu₃Al‐LDH magnetic nanoparticles to prepare the γ‐Fe₂O₃@Cu₃Al‐LDH‐TUD MNPs. The structure and properties of these magnetic nanoparticles were established by FT‐IR, EDX, SEM, XRD, and hystogram of particle size analytical methods. The results obtained from these analytical methods confirmed the successful immobilization of the thiourea dioxide onto the magnetic support. The synthesized magnetic nanoparticles (MNPs) exhibited high catalytic activity in one‐pot three‐component reactions under mild and solvent‐free conditions for the synthesis of diverse ranges of dihydropyrano[3,2‐c]pyrazoles and dihydropyrano[3,2‐c]chromens. All the reactions proceeded smoothly to furnish the respective products in excellent yields. Simple isolation of the products, avoidance of harmful organic solvents, versatility of the catalyst and its easy magnetic separation and reusability with no significant loss of activity are the main advantages of the present method.