Semra Ide

Synthesis, characterization, biological activities of dimethyltin(IV) complexes of Schiff bases with ONO-type donors

Four different dimethyltin(IV) complexes of Schiff bases derived from 2-amino-3-hydroxypyridine and different substituted salicylaldehydes have been synthesized. The compounds, with the general formula [Me(2)Sn(2-OArCH=NC(5)H(3)NO)], where Ar=-C(6)H(3)(5-CH(3)) [Me(2)SnL(1)], -C(6)H(3)(5-NO(2)) [Me(2)SnL(2)], -C(6)H(2)(3,5-Cl(2)) [Me(2)SnL(3)], and -C(6)H(2)(3,5-I(2)) [Me(2)SnL(4)], were characterized by IR, NMR ((1)H and (13)C), mass spectroscopy and elemental analysis. Me(2)SnL(3) was also characterized by X-ray diffraction analysis and shows a fivefold C(2)NO(2) coordination with distorted square pyramidal geometry. H(3)C-Sn-CH(3) angles in the complexes were calculated using Lockharts equations with the (1)J((117/119)Sn-(13)C) and (2)J((117/119)Sn-(1)H) values (from the (1)H-NMR and (13)C-NMR spectra). The in vitro antibacterial and antifungal activities of dimethyltin(IV) complexes were also investigated.

Self-assembled peptide amphiphile nanofibers and peg composite hydrogels as tunable ECM mimetic microenvironment.

Natural extracellular matrix (ECM) consists of complex signals interacting with each other to organize cellular behavior and responses. This sophisticated microenvironment can be mimicked by advanced materials presenting essential biochemical and physical properties in a synergistic manner. In this work, we developed a facile fabrication method for a novel nanofibrous self-assembled peptide amphiphile (PA) and poly(ethylene glycol) (PEG) composite hydrogel system with independently tunable biochemical, mechanical, and physical cues without any chemical modification of polymer backbone or additional polymer processing techniques to create synthetic ECM analogues. This approach allows noninteracting modification of multiple niche properties (e.g., bioactive ligands, stiffness, porosity), since no covalent conjugation method was used to modify PEG monomers for incorporation of bioactivity and porosity. Combining the self-assembled PA nanofibers with a chemically cross-linked polymer network simply by facile mixing followed by photopolymerization resulted in the formation of porous bioactive hydrogel systems. The resulting porous network can be functionalized with desired bioactive signaling epitopes by simply altering the amino acid sequence of the self-assembling PA molecule. In addition, the mechanical properties of the composite system can be precisely controlled by changing the PEG concentration. Therefore, nanofibrous self-assembled PA/PEG composite hydrogels reported in this work can provide new opportunities as versatile synthetic mimics of ECM with independently tunable biological and mechanical properties for tissue engineering and regenerative medicine applications. In addition, such systems could provide useful tools for investigation of how complex niche cues influence cellular behavior and tissue formation both in two-dimensional and three-dimensional platforms.

Structure and characterization of N-(2-hydroxy-1-naphthylidene)threonine

Abstract Threonine Schiff base derived 2-hydroxy-1-naphthaldehyde and threonine has been isolated and investigated. The stoichiometry of this compound was derived from the results of elemental analyses, IR, 1 H-NMR and UV spectroscopic techniques. X-ray diffraction method was also used to obtain the single-crystal structure. The compound crystallizes in the space group P 2 1 with cell dimensions a =5.109(2), b =11.334(2), c=11.155(3) A and β =91(3)° with Z =2. The molecule has phenol-imine tautomeric form in the crystal structure. Some of bond lengths and angles found in the molecular structure are distorted due to π-electron delocalization and steric effect of naphthylidene and threonine groups.

Annealing of Co-Cr dental alloy: effects on nanostructure and Rockwell hardness.

PURPOSE The aim of the study was to evaluate the effect of annealing on the nanostructure and hardness of Co-Cr metal ceramic samples that were fabricated with a direct metal laser sintering (DMLS) technique. MATERIALS AND METHODS Five groups of Co-Cr dental alloy samples were manufactured in a rectangular form measuring 4 × 2 × 2 mm. Samples fabricated by a conventional casting technique (Group I) and prefabricated milling blanks (Group II) were examined as conventional technique groups. The DMLS samples were randomly divided into three groups as not annealed (Group III), annealed in argon atmosphere (Group IV), or annealed in oxygen atmosphere (Group V). The nanostructure was examined with the small-angle X-ray scattering method. The Rockwell hardness test was used to measure the hardness changes in each group, and the means and standard deviations were statistically analyzed by one-way ANOVA for comparison of continuous variables and Tukeys HSD test was used for post hoc analysis. P values of <.05 were accepted as statistically significant. RESULTS The general nanostructures of the samples were composed of small spherical entities stacked atop one another in dendritic form. All groups also displayed different hardness values depending on the manufacturing technique. The annealing procedure and environment directly affected both the nanostructure and hardness of the Co-Cr alloy. Group III exhibited a non-homogeneous structure and increased hardness (48.16 ± 3.02 HRC) because the annealing process was incomplete and the inner stress was not relieved. Annealing in argon atmosphere of Group IV not only relieved the inner stresses but also decreased the hardness (27.40 ± 3.98 HRC). The results of fitting function presented that Group IV was the most homogeneous product as the minimum bilayer thickness was measured (7.11 Å). CONCLUSION After the manufacturing with DMLS technique, annealing in argon atmosphere is an essential process for Co-Cr metal ceramic substructures. The dentists should be familiar with the materials that are used in clinic for prosthodontics treatments.

Supramolecular GAG-like Self-Assembled Glycopeptide Nanofibers Induce Chondrogenesis and Cartilage Regeneration.

Glycosaminoglycans (GAGs) and glycoproteins are vital components of the extracellular matrix, directing cell proliferation, differentiation, and migration and tissue homeostasis. Here, we demonstrate supramolecular GAG-like glycopeptide nanofibers mimicking bioactive functions of natural hyaluronic acid molecules. Self-assembly of the glycopeptide amphiphile molecules enable organization of glucose residues in close proximity on a nanoscale structure forming a supramolecular GAG-like system. Our in vitro culture results indicated that the glycopeptide nanofibers are recognized through CD44 receptors, and promote chondrogenic differentiation of mesenchymal stem cells. We analyzed the bioactivity of GAG-like glycopeptide nanofibers in chondrogenic differentiation and injury models because hyaluronic acid is a major component of articular cartilage. Capacity of glycopeptide nanofibers on in vivo cartilage regeneration was demonstrated in microfracture treated osteochondral defect healing. The glycopeptide nanofibers act as a cell-instructive synthetic counterpart of hyaluronic acid, and they can be used in stem cell-based cartilage regeneration therapies.

Synthesis and characterization of nanomagnetite particles and their polymer coated forms

Superparamagnetic nanoparticles were prepared by coprecipitation of ferrous (Fe(2+)) and ferric (Fe(3+)) aqueous solution by a base. Nanomagnetite particles were coated with poly(St/PEG-EEM/DMAPM) and poly(St/PEG-MA/DMAPM) layer by emulsifier-free emulsion polymerization. Chemical structure of nanoparticles was characterized by both FTIR and (1)H NMR. Particle morphologies were determined by Zeta Sizer, DLS, XRD and SAXS. Structural analysis showed that after polymer coating nanomagnetite particles kept their superparamagnetic property. Besides the synthesized magnetites, polymer coated forms of these particles are more biocompatible, well dispersable and uniform. These properties make them a very strong candidate for bioengineering applications, such as bioseparation, gene transfer.

THE CRYSTAL AND MOLECULAR STRUCTURE OF TWO BENZIMIDAZOLE DERIVATIVES : 1-(PHENYLMETHYL)-2-(4-METHOXYPHENYLMETHYL)-1H-BENZIMIDAZOLE-5-CARBOXYLIC ACID ( I) AND 1,2-DI-(PHENYLMETHYL)-1H-BENZIMIDAZOLE-5-CARBOXYLIC ACID (II)

Abstract The crystal structures of C23H20N2O3 (I) and C22H18N2O2 (II) have been determined by single-crystal X-ray diffraction. These two compounds crystallise in the monoclinic space groups, P 2 1 c and C 2 c . The structures have been determined by direct methods and refined to R, 0.041 (I) and 0.070 (II). The benzimidazole ring systems in (I) and (II) are planar. The phenyl rings attached to N1 and C2 in (I) are planar and make dihedral angles of 88.5(1) and 103.8(1)° with the benzimidazole ring systems. Corresponding angles in (II) are 95.0(2) and 105.1(2)°.

Structural and spectroscopic characteristics of two new dibenzylbutane type lignans from Taxus baccata L.

Abstract Chromatographic separation of chloroform extracts of the heartwood of Taxus baccata L. has yielded two new dibenzylbutane type lignans, together with a known lignan. Their structures were established as 3′-demethylisolariciresinol-9′-hydroxy isopropylether ( 1 ) and 3-demethylisolariciresinol ( 2 ) and isolariciresinol ( 3 ) on the basis of 1D- and 2D-NMR spectroscopic analysis. Compounds 1 and 2 were identified as new lignans of isolariciresinol derivatives. Compound 1 is the first lignan with a hydroxyisopropyl group at C-9′. Molecular mechanic calculations of these compounds were carried out by using mm3 program. Furthermore, the conformations of these three compounds were computed with the semi-empirical molecular orbital methods AM1 and PM3 by using X-ray crystal structure results of similar compounds. So, three-dimensional, the most probable structure of these compounds were obtained, compared and discussed.

Virus-like nanostructures for tuning immune response.

Synthetic vaccines utilize viral signatures to trigger immune responses. Although the immune responses raised against the biochemical signatures of viruses are well characterized, the mechanism of how they affect immune response in the context of physical signatures is not well studied. In this work, we investigated the ability of zero- and one-dimensional self-assembled peptide nanostructures carrying unmethylated CpG motifs (signature of viral DNA) for tuning immune response. These nanostructures represent the two most common viral shapes, spheres and rods. The nanofibrous structures were found to direct immune response towards Th1 phenotype, which is responsible for acting against intracellular pathogens such as viruses, to a greater extent than nanospheres and CpG ODN alone. In addition, nanofibers exhibited enhanced uptake into dendritic cells compared to nanospheres or the ODN itself. The chemical stability of the ODN against nuclease-mediated degradation was also observed to be enhanced when complexed with the peptide nanostructures. In vivo studies showed that nanofibers promoted antigen-specific IgG production over 10-fold better than CpG ODN alone. To the best of our knowledge, this is the first report showing the modulation of the nature of an immune response through the shape of the carrier system.

Structural and spectral studies of N-(3-hydroxypyridine-2-yl)salicylideneimine and N-(3-hydroxypyridine-2-yl)-5-bromosalicylideneimine and their dimethyltin(IV) complexes

Abstract N-(3-hydroxypyridine-2-yl)salicylidineimine (1), N-(3-hydroxypyridine-2-yl)-5-bromo salicylideneimine (2) and their diorganotin(IV) complexes formulated as Me2Sn(OC6H4CH=NC5H3NO) (3) and Me2Sn(OC6H3BrCH=NC5H3NO) (4) were prepared and characterized by 1H-NMR, IR, mass spectroscopy and single crystal x-ray diffraction study. The crystal structures of 3 [orthorhombic, Pbna (no 60); a = 10.439(1) Å, b = 13.388(3) Å, c = 19.340(2) Å, Z = 4; V = 2703(1) Å3] and 4 [monoclinic, P21/a (no 14); a = 7.528(4) Å, b = 16.576(7) Å, c = 12.017(7) Å, β = 97.97(5), Z = 4; V = 1485(1) Å3] have been solved by standard methods and refined by full-matrix least squares (carried out on F2) to R values of 0.066 and 0.046 respectively. The studied tin(IV) complexes (3 and 4) exhibit the distorted trigonal-bipyramidal geometries around Sn atoms, separately. The tautomeric effects of ligands and the substitution of Br atom to the common molecular structure were discussed beside of the coordination geometries of 3 and 4.