Mohammad Khorsand-Ghayeni

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.

Bioactive glasses have shown some interesting biological properties such as biocompatibility, biodegradation, and angiogenesis in skin tissue engineering. In the current research, the effects of MgO- or CoO-doped 64S bioactive glass with a composition of 64 SiO₂-26 CaO-5 P₂O₅-5 MgO or CoO (mol%) were studied in relation with biological properties of electrospun [poly(lactic-co-glycolic acid) (PLGA)/collagen]. PLGA/collagen samples were rinsed in suspension of bioactive glass nanoparticles in distilled water with a concentration of 0.1 w/v and then freeze dried. Cell adhesion, viability, angiogenesis, and ionic release were performed and tested in culture medium containing fibroblast cells. Attachment and viability of fibroblast cells were increased significantly in bioglass-coated samples, while shrinkage in PLGA/collagen scaffold was reduced by the addition of bioactive glass. Vascular endothelial growth factor secretion in coated scaffold was dropped compared to the uncoated samples. This could be attributed to the fast degradation of glass nanoparticles, according to the inductively coupled plasma-atomic emission spectroscopy results.

The aim of this study is to investigate the applicability of poly(lactic-co-glycolic acid) (PLGA)/collagen composite scaffold for skin tissue engineering. PLGA and collagen were dissolved in HFIP as a common solvent and fibrous scaffolds were prepared by electrospinning method. The scaffolds were characterized by scanning electron microscopy (SEM), FTIR spectroscopy, mercury porosimetry, tensile strength, biocompatibility assays and Biodegradation. Cytotoxicity and cell adhesion were tested for two cell line groups, human dermal fibroblast (HDF) and human keratinocyte (HaCat). SEM images showed appropriate cell adhesion to the scaffold for both cell lines. MTT assays indicated that the cell viability of HDF cells increased with time, but the number of HaCat cells decreased after 14 days. The ultimate tensile strength was suitable for skin substitute application, but its elongation at break was rather low. For successful clinical application of the PLGA/collagen scaffold, some properties especially mechanical strain needs to be improved.

Skin damage can occur for many reasons, including burns and injuries, which in extreme cases can even lead to death. Different methods such as electrospinning are used to produce scaffolds used in skin tissue engineering. Natural and synthetic polymers were used in this method. It was observed that the use of both natural and synthetic polymers gives better results for cell culturing rather than using of each material solely. In this study, scaffolds of poly(lactic-co-glycolic acid) and collagen were prepared using coating and common solvent methods. The characteristics of samples were evaluated through scanning electron microscopy, porosimetry, mechanical testing, degradation behavior, and in vitro assays. The mechanical and biocompatibility test results of the scaffold prepared by coating method were better than the other one. However, the degradation rate of the common solvent was nearly five times more than coating sample that leads to cytotoxicity in contact with the skin cells.