Functional Polyimide-Based Electrospun Fibers for Biomedical Application

The current study focuses on the application of cytotoxicity tests upon one membrane matrix based on electrospun polyimide fibers, appealing for biomedical application, such as scaffolds for cell growth, patches or meshes for wound healing, etc. Assays were performed in order to determine the viability and proliferation of L929 murine fibroblasts after they were kept in direct contact with the studied electrospun polyimide fibers. Increased cell viability and proliferation were detected for cells seeded on electrospun polyimide fibers membrane, in comparison with the control system, either after two or six days of evaluation. The number of live cells was higher on the studied material compared to the control, after two and six days of cell seeding. The tendency of the cells to proliferate on the electrospun polyimide fibers was revealed by confocal microscopy. The morphological stability of electrospun polyimide membrane was evaluated by SEM observation, after immersion of the samples in phosphate buffer saline solution (PBS, 7.4 at 37 °C) at various time intervals. Additionally, the easy production of electrospun polyimide fibers can facilitate the development of these types of matrices into specific biomedical applications in the future.

Corrosion behaviour of austenitic stainless steels in phosphate buffer saline solution: synergistic effects of protein concentration, time and nitrogen

Adsorption of protein on a steel surface decreases the corrosion rate, while the formation of metal–protein complexes followed by detachment enhances the corrosion rate.

Primordial germ cells profiles incubated for 24 hours in phosphate buffer saline [-] solution

Gonadal development is a sequential process that can be divided into three major events: the PGCs migration, sex determination and gonadal differentiation. This study was aimed to see the development of PGCs isolated from the gonads of embryos after being incubated for 7 days and then was incubated using a solution of Phosphate Buffer Saline (PBS) [-]. The developing gonad can be isolated from 7 days old chick and can be incubated at a temperature of 37.8^oC in a solution of PBS [-]: without Ca2+ and Mg2+. The release of gonadal PGC was observed within 1, 8, 16, and 24 hours after the embryonic gonad was placed in a PBS solution [-]. The results showed that PGCs can be separated from gonadal tissues and can be collected by entering the developing gonad to the PBS [-] solution. The highest percentage of PGCs and survival rate was obtained after gonad was incubated for 1 hour and was not different with 8 hours (P>0.05). Those result was significantly different (P<0.05) with the 16 and 24 hours incubation. The highest purity rate percentage was in the 8 hours incubation, but did not show a significant difference (P>0.05) with the 1 and 16 hours incubation. The percentage of the purity differed (P<0.05) after the 24 hours incubation. It can be concluded that the most appropriate incubation time to obtain PGCs from the KUB chicken embryonic gonad is no more than 8 hours.

Biodegradable Chitosan-Silicate Porous Hybrids for Drug Delivery

Porous chitosan-silicate hybrids were prepared by freeze-drying the precursor sol solutions synthesized from chitosan and 3-glycidoxypropyltrimethoxysilane (GPTMS). Degradability of and the release of cytochrome C in to phosphate buffer saline solution (PBS) were examined as a function of the GPTMS content. The hybrids were less degradable with larger GPTMS contents, and the cytochrome C release profile was so controllable as to give either burst release or slow one due to the GPTMS content. Thus, the present porous chitosan-silicate hybrids were considered applicable to drug delivery systems.

Study of controlled tetracycline release from porous calcium phosphate/polyhydroxybutyrate composites

Porous calcium phosphate ceramics were prepared by sintering of mixtures of nanocrystalline apatitic calcium phosphate and fibrous natural cotton cellulose after pressing at temperatures of 1150 °C and 1250 °C. Micro-and macropores were present in microstructures of ceramic samples. The microstructures of porous ceramics were similar to those observed in bone tissues and fiber-like randomly oriented texture was observed in ceramics. Polyhydroxybutyrate (PHB) biopolymer layers are distributed homogeneously in the samples after evaporation of the diluent (chloroform) from the PHB vacuum impregnated porous samples. The tetracycline (TTC) release rate decreases with the content of polyhydroxybutyrate in the ceramic samples, which corresponds to the rise in amount of biopolymer displaced in the pores of ceramics. The concentration of TTC in the phosphate buffer saline solution varies almost linearly with time after the first seven hours from the start of the release of the calcium phosphate ceramic samples with 2.4 mass % of polyhydroxybutyrate. The initial burst effect was significantly depressed by the preparation method used.