Electrospinning is a versatile technique for fabrication of made-on-purpose biomimetic scaffolds. In this study, optimized electrospun fibrous membranes were produced by simultaneous electrospinning of polycaprolactone (PCL) and polyvinylpyrrolidone (PVP), followed by the selective removal of PVP from the PCL/PVP mesh. After aminolysis, a blend of collagen/chitosan was grafted on the surface. Physicochemical characterizations as well as in vitro evaluations were conducted using different methods. Successful cell infiltration into samples was observed. It seems that the positive trend of cell ingress originates from the proper pore size obtained after removal of pvp (from 4.46 μm before immersion in water to 33.55 μm after immersion in water for 24 h). Furthermore, grafting the surface with the collagen/chitosan blend rendered the scaffolds more biocompatible with improved attachment and spreading of keratinocyte cell lines (HaCaT). Viability evaluation through MTT assay for HDF cells did not reveal any cytotoxic effects. Antibacterial assay with Staphylococcus aureus as Gram-positive and Escherichia coli as Gram-negative species corroborated the bactericidal effects of chitosan utilized in the composition of the coated blend. The results of in vitro studies along with physicochemical characterizations reflect the great potentials of the produced samples as scaffolds for application in skin tissue engineering.

Chitosan due to outstanding properties including biocompatibility, biodegradability, nontoxicity and antibacterial activity has received considerable attention in different fields of biomedical engineering. To study the effect of morphology and topology on antibacterial activity of chitosan, two samples of PVA/Chitosan blend with the same concentration and volume ratio were prepared using electrospinning and film casting methods. To improve the electrospinability of chitosan, it was hydrolyzed by 50% V NaOH solution (95 °C for 48 h.) and PVA was used as an auxiliary polymer for electrospinning. The best electrospinning parameters for producing beadless structure were determined at a voltage of 21 kV and distance of 15 cm. Different physical and chemical characterizations of produced samples were performed using scanning electron microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR), viscosimetry, Atomic Force Microscopy (AFM) and antibacterial assay by two different bacterium strains including Escherichia coli (E.coli) as the gram-negative and Staphylococcus aureus (S.aureus) as the gram-positive bacteria. Antibacterial assays revealed higher sensitivity of E.coli in comparison with S.aureus in the two samples. Also, it revealed that nanotopography of surface wielded influence on the antibacterial activity of samples.

Powder metallurgy process was used in this work to produce NiTi specimens. Uniaxial compression, X-ray diffraction and differential scanning calorimetry were used for characterising the produced samples. L9 orthogonal arrays were chosen based on the Taguchi method for conducting the experiments. In order to optimise the processing parameters and also to determine the level of importance of each parameter, experiments were performed based on grey relational method. Our goal was to optimise recoverable strain ( ε) and the finishing temperature of austenitic transformation ( A_f). Sintering time, compaction pressure, milling time and the atomic percentage of Cu were all selected as controllable parameters. Our results reveal that the sintering time and the atomic percentage of Cu are the most significant parameters. The findings were verified through a confirmatory test.