Magnetic chitosan nanocomposite: As a novel catalyst for the synthesis of new derivatives of N-sulfonylamidine and N-sulfonylimidate.

This study reports the synthesis and characterization of a highly active catalyst based on chelated copper iodide on magnetic chitosan-salicylaldehyde Schiff base. This catalyst was successfully used for the three-component reaction of N-propargylphthalimide, tosylazide, and NH or OH containing nucleophiles to access new classes of N-sulfonylamidine or N-sulfonylimidate derivatives. The products, which were constructed via an in situ generated sulfonyl keteneimine intermediate, were obtained in good to excellent yields. Short reaction times, easy separation and reusability without significant loss of catalyst activity were found to be the notable features of this synthetic protocol.

Synthesis and characterization of PEG-functionalized graphene oxide as an effective pH-sensitive drug carrier.

In the present work, PEG4000 as a hydrophilic polymer was conjugated to the surface of graphene oxide (GO) for effective drug loading and targeting release of doxorubicin. The synthesized nanohybrid was characterized with scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD) and Fourier-transformed infrared spectroscopy (FTIR). Doxorubicin as an anticancer drug was immobilized on the nanohybrid surface, and the release profile at two diverse pH besides the MTT assay was investigated. The IC50 value for the nanohybrid obtained was 0.31 µg/mL. In this work, PEG4000 as a biocompatible polymer grafted on the GO surface to increase the biodispersibility of the drug carrier in a biological environment, but it is the first report of PEG 4000-GO nanohybrid-based drug carrier.

A polyglycerol-polycaprolactone-polycitric acid copolymer and its self-assembly to produce medium-responsive nanoparticles.

A hyperbranched-linear-hyperbranched amphiphile (HLHA) consisting of polyglycerol, polycaprolactone and polycitric acid blocks was synthesized and characterized. The self-assembly of HLHA in aqueous solutions produced nearly monodispersed nanoparticles. The average size of the nanoparticles in aqueous solutions was 120 nm. Spectroscopy and microscopy analysis showed that the nanoparticles change their structure in response to changes in the polarity of the medium in the solution state, so that the hydrophobicity or hydrophilicity of the solvent dominates the structure and properties of the nanoparticles. This property was used to load hydrophobic anticancer drugs inside the nanoparticles and also to deliver them to cancer cells successfully. In addition to the mentioned properties, the efficient uptake and low toxicity enable the prepared nanoparticles to be potential new systems for future cancer therapy.

Preparation of Zinc (II) and cadmium (II) complexes of the tetradentate Schiff base ligand 2-((E)-(2-(2-(pyridine-2-yl)- ethylthio)ethylimino)methyl)-4-bromophenol (PytBrsalH).

We describe the synthesis and characterization of two new zinc (II) and cadmium (II) complexes of the tetradentate dissymmetric Schiff base ligand 2-((E)-(2-(2-(pyridine-2-yl)ethylthio)ethylimino)methyl)-4-bromophenol (PytBrsalH), prepared from 1-(2-pyridyl)-3-thia-5-aminopentane (pyta) and 5-bromosalicylaldehyde. The complexes were synthesized by treating an ethanolic solution of the ligand with equimolar amounts of appropriate metal salts in 1 M methanolic solution of NaOH or alternatively, by a more direct route in which the two reactants are added to a solution of the ligand immediately after formation of the latter and prior to any isolation. The complexes were characterized by elemental analysis, FTIR, (1)H-NMR, electronic spectra and molar conductivity. According to obtained data, the probable coordination geometries of zinc and cadmium in these complexes with mixed N, S and O donor atoms are tetrahedral- and octahedral-like,respectively. Both complexes were found to be 1:1 electrolyte systems in acetonitrile.