Nano-TiO2 an Efficient, Clean and Eco-friendly Catalyst for Synthesis of Naphthoxazinone Derivatives as High Potent Antibacterial Agents

Oxazines naturally occurs and synthetically exhibit wide-ranging biological activity. In this study, a highly practical and efficient of 1,2-dihydro-1-phenylnaphtho[1,2-e][1,3]oxazine-3-one derivatives was developed via a multi-component reaction of 2-naphthol, aldehydes and urea in the presence of nano-titanium oxide as solid, recyclable catalyst at one-pot and solvent-free conditions. These synthetic compounds 2a-e were evaluated as potential antibacterial agents. The structures of products were confirmed by spectral analysis FT-IR and 1H NMR. The antibacterial activity of the compounds was screened against Staphylococcus aureus and Escherichia coli. These results showed that these compounds exhibited significant to moderate activities against both Gram (+) and Gram (-) organisms

Harvesting epithelial cell sheet based on thermo- sensitive hydrogel

Thermo-sensitive hydrogels were prepared by graft copolymerization of chitosan and N-Isopropylacrylamide via gamma radiation. Characterization of hydrogels such as 13C-NMR, DSC analysis and swelling test and cell assessments for harvesting living cell sheet were investigated. 13C-NMR and DSC analysis showed chitosan and NIPAAm monomer were grafted via gamma radiation successfully. Swelling ratio and curves results administrated hydrophilicity / hydrophobicity of hydrogel that this property is due to presence of PNIPAAm in different temperatures. The hydrogel was tested for harvesting epithelial cells after carrying out cell culture at 37 °C and incubating the confluent cells at 4°C for spontaneous detachment of cell sheet from hydrogel surface without enzyme treatment. Cell viability assay results and microscopic observations demonstrated that cells could attach to the hydrogel surface and maintain high viability and proliferation ability. Cell detachment efficiency from the hydrogel was high. These unique properties of the hydrogel would make it a promising support for epithelial cell grafting especially cornea regeneration

Types of neural guides and using nanotechnology for peripheral nerve reconstruction

Peripheral nerve injuries can lead to lifetime loss of function and permanent disfigurement. Different methods, such as conventional allograft procedures and use of biologic tubes present problems when used for damaged peripheral nerve reconstruction. Designed scaffolds comprised of natural and synthetic materials are now widely used in the reconstruction of damaged tissues. Utilization of absorbable and nonabsorbable synthetic and natural polymers with unique characteristics can be an appropriate solution to repair damaged nerve tissues. Polymeric nanofibrous scaffolds with properties similar to neural structures can be more effective in the reconstruction process. Better cell adhesion and migration, more guiding of axons, and structural features, such as porosity, provide a clearer role for nanofibers in the restoration of neural tissues. In this paper, basic concepts of peripheral nerve injury, types of artificial and natural guides, and methods to improve the performance of tubes, such as orientation, nanotechnology applications for nerve reconstruction, fibers and nanofibers, electrospinning methods, and their application in peripheral nerve reconstruction are reviewed

A new method in the production of protective sheets against X-ray radiation

Today, the use of X-rays in diagnosing and sometimes treating patients is inevitable. Despite the many benefits of using X-rays in medical and other sciences, the harmful effects of this radiation on human tissue should not be neglected. One of the best ways to prevent the harmful effects of X-rays on the human body is to use appropriate covers against these rays. It seems that it is necessary to find effective particles to weaken X-rays and choose a suitable substrate with high mechanical resistance to scatter particles in it. In this study, the synthesis of SnO2 nanoparticles from SnCl2.2H2O precursor and BaSO4 nanoparticles from BaCl2.2H2O precursor using neem tree extract (Azadirachta indica) as a reducing and stabilizing agent is reported. After the synthesis of nanoparticles, their structure was investigated by X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analysis. Then the desired composite and nanocomposite were prepared in the polymer substrate. The sheets were prepared using an extruder and then a hot hydraulic press. The output sheets had a thickness of 1 mm. The structural characteristics of the produced sheets such as surface morphology, density of prepared composites, mechanical properties, thermal gravimetric analysis and retention of loaded particles after three times washes were investigated. The X-ray attenuation capability of each sample was evaluated by calculating the linear attenuation coefficient for each prepared sample. The results show that all sheets filled with tin and barium micro and nano particles have more X-ray attenuation capabilities than pure polymer. Among the prepared sheets, the nanocomposite prepared from low-density polyethylene (77 %) + SnO2 (10 %) + BaSO4 (10 %) + multi-walled carbon nanotubes (3 %) showed the highest X-ray attenuation