Investigation of culture conditions for biosynthesis of silver nanoparticles using Aspergillus fumigates

In this study, silver nanoparticles were synthesized using the fungus, Aspergillus fumigatus. The effects of three independent variables including glucose content of culture media, initial pH and initial spore concentration on biosynthesis of silver nanoparticles were investigated. These variables affect cell morphology, cell mass, size and morphology of silver nanoparticles and degree of silver ion reduction. The formation of silver nanoparticles was confirmed spectrophotomterically. Size and morphology of silver nanoparticles were investigated using transmission electron microscopy [TEM]. The effects of culture conditions on cell mass concentration as well as the amount and size of synthesized silver nanoparticles were studied. As a result, the optimum culture condition for biosynthesis of silver nanoparticles consisted of a glucose concentration of 16 g/l, pH of 4.5 and spore concentration of 1.5x10[7] spore/l. TEM micrographs showed that the size of nanoparticles in the sample synthesized under optimized condition was in the range of 7-19 nm

Fabrication of porous hydroxyapatite-gelatin scaffolds crosslinked by glutaraldehyde for bone tissue engineering

In this study, to mimic the mineral and organic components of natural bone, hydroxyapatite[HA] and gelatin[GEL] composite scaffolds were prepared using the solvent-casting method combined with a freeze drying process. Glutaraldehyde[GA] was used as a cross linking agent and sodium bisulfite was used as an excess GA discharger. Using this technique, it is possible to produce scaffolds with mechanical and structural properties close to those of the natural trabecular bone. The prepared scaffold has an open, interconnected porous structure. It was found that the GEL/HA ratio with a 50 wt% [weight percent] HA has the compressive modulus, the ultimate compressive stress and elongation similar to those for the trabecular bone. The chemical bonding and the microstructure of the composites were investigated by FT-IR [Fourier Transform Infra Red], SEM [Scanning Electron Microscopy] and Light microscopy, indicating the presence of bonds between Ca2[+] ions of HA and R-COO- ions of GEL in the HA-GEL composite scaffolds. It was found that the addition of HA content can reduce the water absorption and porosity of scaffold. The porosity and the apparent density of 50 wt% HA scaffold were also calculated. The biological responses of scaffolds were examined in L929 fibroblast cell culture, showed partially proliferation of cells around and on the composite surface