PEG–Anthracene Hydrogels as an On‐Demand Stiffening Matrix To Study Mechanobiology

There is a growing interest in materials that can dynamically change their properties in the presence of cells to study mechanobiology. Herein, we exploit the 365 nm light mediated [4+4] photodimerization of anthracene groups to develop cytocompatible PEG‐based hydrogels with tailorable initial moduli that can be further stiffened. A hydrogel formulation that can stiffen from 10 to 50 kPa, corresponding to the stiffness of a healthy and fibrotic heart, respectively, was prepared. This system was used to monitor the stiffness‐dependent localization of NFAT, a downstream target of intracellular calcium signaling using a reporter in live cardiac fibroblasts (CFbs). NFAT translocates to the nucleus of CFbs on stiffening hydrogels within 6 h, whereas it remains cytoplasmic when the CFbs are cultured on either 10 or 50 kPa static hydrogels. This finding demonstrates how dynamic changes in the mechanical properties of a material can reveal the kinetics of mechanoresponsive cell signaling pathways that may otherwise be missed in cells cultured on static substrates.     

Ni(II), Cu(II), and Zn(II) complexes of tetradentate schiff base containing two thiadiazoles units: Structural,spectroscopic, magnetic properties,and molecular modeling studies

Four new mononuclear metal complexes with a mononucleating Schiff base ligand containing two thiadiazoles units have been synthesized. The ligand and metal complexes were characterized by elemental analyses, IR, ¹H, and ¹³C NMR, UV–vis, ESR, electrospray ionization mass spectra, and magnetic susceptibility measurements. Electronic spectra, magnetic susceptibility measurement, and molecular modeling studies support octahedral geometry around the Ni(II), Cu(II), and Zn(II) ions. The magnetic properties were investigated, and ferromagnetic coupling is observed in Cu(II) and Ni(II) complexes. In addition, total energy and heat of formation calculated for conformers of the Schiff base ligand by the semiempirical AM1 calculations have shown that E,Z‐isomer of the ligand is more stable (about 5.3 kcal/mol) than E,E‐ and Z,Z‐isomers. © 2008 Wiley Periodicals, Inc. Heteroatom Chem 19:700–712, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20496     

Electrical and photoelectrical behaviour of heterojunctions based on novel oligomeric metal complexes

Naringenin‐based Schiff base ligands with 4‐aminobenzoic hydrazide were obtained as a unilateral form ( L¹ ). The ligand was oligomerized by oxidative polycondensation reaction with NaOCl as an oxidant in an aqueous alkaline medium at 90 °C to form a functional oligomer ( L² ), and its transition metal complexes such as those with Cu(II), Ni(II) and Zn(II) were prepared. The monomer and the oligomeric compounds were characterized using various techniques. Optical and electrical properties of the complexes were also investigated. All compounds showed indirect band gaps and they can be accepted as being in the semiconductor class. Organic–inorganic hybrid devices were obtained using n‐Si inorganic semiconductor and the complexes. The characteristic parameters of the devices were determined using current–voltage (I–V) and capacitance–voltage measurements in the dark. Photoelectrical properties of the devices were investigated using I–V measurements under a solar simulator with an AM1.5 global filter. Copyright © 2015 John Wiley & Sons, Ltd.     

A High Sensitive,Reproducible and Disposable Immunosensor for Analysis of SOX2

In this study, an ITO (indium tin oxide) based biosensor was constructed to detect SOX2. SOX2 helps the regulation of cell pluripotency and is closely related to early embryonic development, neural and sexual differentiation. SOX2 is amplified and overexpressed in some malignant tumors such as squamous cell, lung, prostate, breast, esophageal cell, colon, ovarian, glioblastoma, pancreatic cancer, gastric cancer, head and neck squamous cell carcinoma. To generate a hydroxylated clean electrode surface, ITO electrodes were treated with NH₄OH/H₂O₂/H₂O. Later, ITO‐PET electrode surfaces were modified with 3‐glycidoxypropyl trimethoxysilane (3‐GOPS). Then, Anti‐SOX2 was covalently immobilized onto the electrode surfaces. 3‐GOPS concentration, Anti‐SOX2 concentration and incubation time, SOX2 incubation time were optimized. Electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) were utilized in order to follow up the immobilization processes and the optimization steps of the biosensor. To characterize the analytical properties of constructed immunosensor; linear range, repeatability, reproducibility and regeneration studies were investigated. The linear range of the immunosensor was detected as 0.625 pg/mL–62.5 pg/mL. Square wave voltammetry technique was also applied to the biosensor. Storage life of the biosensor was determined for identifying the possible usability of the biosensor in clinical field. Finally, the designed biosensor was applied to the real human serum samples. The results obtained with the presented biosensor were also compared with ELISA results.     

A Practical Approach for the Detection of Protein Tau with a Portable Potentiostat

Along with many factors, the change in protein tau isoforms, which has an obvious role in the function of microtubules, is an important biomarker of Alzheimer's disease. The aim of this study is to determine the protein Tau-441 with a portable potentiostat using a practical approach. For this purpose, screen printed electrodes (SPCEs) were first hydroxylated and then functional self-assembled monolayers were formed on the surface with 3-aminopropyltriethoxysilane (APTES). Evidence of anti-Tau being immobilized on to the surface was followed by techniques such as cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS) and Fourier transform infrared spectroscopy (FTIR). The constructed immunosensor showed a linear response within the concentration range of 0.0064–0.8 ng/mL for the target analyte Tau-441 and the limit of detection was found to be 0.0053 ng/mL. In addition, analytical behaviors such as reproducible measurements and storage life of the developed immunosensor with a portable potentiostat were also investigated. It has been demonstrated that Tau-441 can be captured with the help of portable device with sensitivity in CSF environment.     

Incorporation of an allene unit into 1,4-dihydronaphthalene: generation of 1,2-benzo-1,4,5-cycloheptatriene and its dimerization

1-Bromo-1-fluoro-[1a,2,7,7a]-tetrahydro-1H-cyclopropa[b]naphthalene (19) has been prepared by the addition of bromofluorocarbene to 1,4-dihydronaphthalene (18). Treatment of a solution of 19 in dry ether with MeLi afforded the tricyclic hydrocarbon 17, resulting from the intramolecular C-H insertion of carbene 16, and two dimerization products, the head-to-head 20 and head-to-tail 21 allene dimers, confirming the formation of title cycloallene 15 as a reactive intermediate. B3LYP/6-31G(d) calculation predicts the activation barriers for insertion product 17 and allene product 15 as 3.70 and 9.52 kcal/mol, respectively. This prediction was in good agreement with our experimental results.     

Synthesis,characterization and electrochemical properties of novel metal free and zinc(II) phthalocyanines of ball and clamshell types

The phthalodinitrile derivative 1 was prepared by the reaction of 4-nitrophthalonitrile and 1,3-dimethoxy-4-tert-butylcalix[4]arene in dry dimethylsulfoxide as the solvent, in the presence of the base K₂CO₃, by nucleophilic substitution of an activated nitro group in an aromatic ring. The tetramerization of compound 1 gave a binuclear zinc(II) phthalocyanine and a metal-free phthalocyanine of the ball type, 2 and 3, respectively. Its condensation with 4,5-bis(hexylthio)phthalonitrile results in a binuclear phthalocyanine of the clamshell type, 4. The newly synthesized compounds were characterized by elemental analysis, UV–Vis, IR, MS and ¹H NMR spectra. The electronic spectra exhibit an intense π → π^∗ transition with characteristic Q and B bands of the phthalocyanine core. The electrochemical properties of 2–4 were examined by cyclic voltammetry in non-aqueous media. The voltammetric results showed that while there is no considerable interaction between the two phthalocyanine rings in 4, the splitting of a molecular orbital occurs as a result of the strong interaction between the phthalocyanine rings in 2 and 3.     

Solvent Effect upon Ion-pair Extraction of Different Sodium Dyes Using Some Crown Ethers

Liquid-liquid extractive-spectrophotometric studies of sodium ion complexes of 18-crown-6(18C6), dibenzo-18-crown-6(DB18C6), 15-crown-5(15C5), and 12-crown-4(12C4) and anionic dyes [4-(2-pyridylazo)-resorcinol monosodium salt monohydrate (PAR), Eriochrom Black T (EBT), and methyl orange (MOR)] and sodium picrate (PICRAT) as the counter ion are described. The overall extraction equilibrium constants for the 1 : 1 complexes of the above crown ethers with sodium dyes between different organic solvents and water have been determined at 25deg;C. They were conducted in various solvent-water systems maintaining an identical initial cation concentration in water, [M0+]w, and macrocyclic ligand concentration in the organic phase, [L0]org}, so that in all extractions [M0+]w : [L0]org ratios were 1 : 1, 1 : 10, 1 : 20, 1 : 50, and 1 : 62.5. An ion association complex formed between the sodium-crown ether complex ion and a dye anion was extracted into the organic solvent, and then the dye concentration of the separated aqueous phase was measured with an ultraviolet-visible spectrophotometer. PAR was the best associated dye with all crown ethers sodium-dyes and the extracted dye occurs as the ion-pair complex. Methylene chloride was found to be better than other extractive solvents used in this study.     

4,4′‐Butane‐1,4‐diylbis[3‐ethyl‐1H‐1,2,4‐triazol‐5(4H)‐one] and 4‐hydr­oxy‐3‐n‐prop­yl‐1H‐1,2,4‐triazol‐5(4H)‐one

The title compounds, C₁₂H₂₀N₆O₂, (I), and C₅H₉N₃O₂, (II), display the characteristic features of 1,2,4‐triazole derivatives. Compound (I) lies about an inversion centre which is at the mid‐point of the central C—C bond. Compound (II) also contains a planar 1,2,4‐triazole ring but differs from (I) in that it has a hydr­oxy group attached to the ring. Mol­ecules of (I) are held together in the crystal structure by inter­molecular N—H⋯O contacts and by weak π–π stacking inter­actions between the 1,2,4‐triazole moieties. Compound (II) contains inter­molecular O—H⋯O and N—H⋯O hydrogen bonds.     

IR spectroscopic studies on the transmission of substituent effects to carbonyl and thiocarbonyl stretching frequencies in 4-substituted phenyl-4,5-dihydrobenzo [f] [1,4] oxazepin-3 (2H)-ones (thiones)

Single and dual substituent correlation analysis were applied to study transmission of substituent effects on IR carbonyl and thiocarbonyl stretching frequencies of 4-substituted phenyl-4,5-dihydrobenzo [f] [1,4] oxazepin-3 (2H)-ones (5a–n) and -thiones (6a–n). The substituent effects were estimated on the basis of results of the statistical analysis. The differences among the regression coefficients were discussed in terms of the relative importance of the substituent field and resonance effects. For a better understanding of the results, density functional theory (DFT) calculations were performed to determine the preferred geometry and to calculate the theoretical carbonyl and thiocarbonyl stretching frequencies.