Among several attempts to integrate tissue engineering concepts into strategies to repair different parts of the human body, neuronal repair stands as a challenging area due to the complexity of the structure and function of the nervous system and the low efficiency of conventional repair approaches. Herein, electrospun polyvinyl alcohol (PVA)/chitosan nano-fibrous scaffolds have been synthesized with large pore sizes as potential matrices for nervous tissue engineering and repair. PVA fibers were modified through blending with chitosan and porosity of scaffolds was measured at various levels of their depth through an image analysis method. In addition, the structural, physicochemical, biodegradability, and swelling of the chitosan nanofibrous scaffolds were evaluated. The chitosan-containing scaffolds were used for in vitro cell culture in contact with PC12 nerve cells, and they were found to exhibit the most balanced properties to meet the basic required specifications for nerve cells. It could be concluded that addition of chitosan to the PVA scaffolds enhances viability and proliferation of nerve cells, which increases the biocompatibility of the scaffolds. In fact, addition of a small percentage of chitosan to the PVA scaffolds proved to be a promising approach for synthesis of a neural-friendly polymeric blend.

The functionality of tissue engineering scaffolds can be enhanced by localized delivery of appropriate biological macromolecules incorporated within biodegradable nanoparticles. In this research, chitosan/58S-bioactive glass (58S-BG) containing poly(lactic-co-glycolic) acid (PLGA) nanoparticles has been prepared and then characterized. The effects of further addition of 58S-BG on the structure of scaffolds have been investigated to optimize the characteristics of the scaffolds for bone tissue engineering applications. The results showed that the scaffolds had high porosity with open pores. It was also shown that the porosity decreased with increasing 58S-BG content. Furthermore, the PLGA nanoparticles were homogenously distributed within the scaffolds. According to the obtained results, the nanocomposites could be considered as highly bioactive bone tissue engineering scaffolds with the potential of localized delivery of biological macromolecules.

Among many shape memory alloys, nickel-titanium (NiTi) alloys are popular due to their superior properties in shape memory effect and superelasticity. They are presently often used in microengineering and medical technology especially in orthopedic and orthodontic implants due to their specific properties. In this study, the electric discharge machine characteristics of NiTi shape memory alloys have been fully investigated by full factorial design. Analysis of mean showed that the material removal rate of NiTi in the electric discharge machine process significantly related to the electrodischarge energy, involving the pulse current and pulse duration. Many electrodischarge craters and recast layers were observed on the electric discharge machine surface of NiTi samples. In addition, there was no significant difference between copper (Cu) and tungsten-copper (W-Cu) electrodes in material removal rate but work stability of W-Cu electrode was longer. On the contrary, quantity of impurity on the surface of the Cu electrode was lower. The specimen's hardness near the outer surface could reach 1200 Hv, which originated from the hardening effect of the recast layer. Here, the microstructure, composition, and hardness of electric discharge machine surfaces are also discussed.

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