Hadi Hajiali

Electrospun PGA/gelatin nanofibrous scaffolds and their potential application in vascular tissue engineering

Background and methods In this study, gelatin was blended with polyglycolic acid (PGA) at different ratios (0, 10, 30, and 50 wt%) and electrospun. The morphology and structure of the scaffolds were characterized by scanning electron microscopy, Fourier transform infrared spectroscopy, and differential scanning calorimetry. The mechanical properties were also measured by the tensile test. Furthermore, for biocompatibility assessment, human umbilical vein endothelial cells and human umbilical artery smooth muscle cells were cultured on these scaffolds, and cell attachment and viability were evaluated. Results PGA with 10 wt% gelatin enhanced the endothelial cells whilst PGA with 30 wt% gelatin increased smooth muscle cell adhesion, penetration, and viability compared with the other scaffold blends. Additionally, with the increase in gelatin content, the mechanical properties of the scaffolds were improved due to interaction between PGA and gelatin, as revealed by Fourier transform infrared spectroscopy and differential scanning calorimetry. Conclusion Incorporation of gelatin improves the biological and mechanical properties of PGA, making promising scaffolds for vascular tissue engineering.

Fibrous wound dressings encapsulating essential oils as natural antimicrobial agents

Preventing infections is one of the main focuses of wound care. The colonisation of wounds by microorganisms can in fact have negative consequences on the healing process, delaying it. Here, we propose the use of essential oils as natural antimicrobial agents for cellulose-based fibrous dressings. We demonstrate the production of composite electrospun fibres that effectively encapsulate three different types of essential oils (cinnamon, lemongrass and peppermint). The fibrous scaffolds are able to inhibit the growth of Escherichia coli, even when small amounts of essential oils were used. At the same time, they are not cytotoxic, as proved by biocompatibility assays on skin cell models. The created dressings are promising as advanced biomedical devices for topical treatments.

Alginate–lavender nanofibers with antibacterial and anti-inflammatory activity to effectively promote burn healing

One of the current challenges in wound care is the development of multifunctional dressings that can both protect the wound from external agents and promote the regeneration of the new tissue. Here, we show the combined use of two naturally derived compounds, sodium alginate and lavender essential oil, for the production of bioactive nanofibrous dressings by electrospinning, and their efficacy for the treatment of skin burns induced by midrange ultraviolet radiation (UVB). We demonstrate that the engineered dressings reduce the risk of microbial infection of the burn, since they stop the growth of Staphylococcus aureus. Furthermore, they are able to control and reduce the inflammatory response that is induced in human foreskin fibroblasts by lipopolysaccharides, and in rodents by UVB exposure. In particular, we report a remarkable reduction of pro-inflammatory cytokines when fibroblasts or animals are treated with the alginate-based nanofibers. The down-regulation of cytokines production and the absence of erythema on the skin of the treated animals confirm that the here described dressings are promising as advanced biomedical devices for burn management.

Alginate nanofibrous mats with adjustable degradation rate for regenerative medicine

The broad utilization of electrospun scaffolds of sodium alginate in tissue engineering is strongly limited by their high solubility in aqueous environments and by the difficulty to adjust their degradation dynamics. Here, an alternative strategy to enhance the stability and to control the degradability of alginate nanofibers is described by treating them with trifluoroacetic acid for specific time intervals. It is demonstrated that, by increasing the duration of the acid treatment procedure, a lower degradation rate of the resulting fibers in buffer solutions can be achieved. Furthermore, the produced mats are free from cytotoxic compounds and are highly biocompatible. The properties conferred to the alginate nanofibrous mats by the proposed method are extremely attractive in the production of innovative biomedical devices.

The influence of bioglass nanoparticles on the biodegradation and biocompatibility of poly (3-hydroxybutyrate) scaffolds

Nanocomposite scaffolds have been developed in order to achieve better mechanical and physiological properties in bone tissue engineering applications. In this study, reinforced poly (3-hydroxybutyrate) (PHB) composite scaffolds made with different weight ratios of nanobioglass (0, 2.5, 5, 7.5, and 10 wt%) and various porosities (70, 80 and 90 wt% of NaCl) were prepared by the salt leaching process. The scaffolds were placed in a PBS solution and their weight loss was measured. The biocompatibility of samples was examined in vitro using the MG63 cell line by indirect test, cell proliferation, and alkaline phosphatase (ALP) assays. Cell attachment on the surface of the scaffolds was observed by scanning electron microscopy (SEM). The biodegradation results showed that increasing the volume fraction of porosity and concentration of bioglass nanoparticles enhanced the weight loss of the scaffolds. The cell study demonstrated that a certain concentration of nanobioglass (7.5 wt%) in the scaffolds can significantly improve cell proliferation, inducing better osteoconductivity, compared to that of the pure PHB scaffolds and controls. In addition, the SEM results showed high cell attachment on these samples. All these factors indicate that samples with 7.5 wt% nanobioglass are a promising scaffold for bone tissue engineering.

Photo-polymerisable electrospun fibres of N-methacrylate glycol chitosan for biomedical applications

The availability of nanofibrous substrates with engineered properties, such as controlled porosity, mechanical conformability, biodegradation profile and drug release, is of strategic importance in the biomedical sector. Here, we demonstrate that N-methacrylate glycol chitosan, a photo-polymerisable, biocompatible and water-soluble derivative of chitosan, can be easily processed to create non-woven mats of nanofibres with controlled physicochemical characteristics. The produced fibrous mats are characterised by thermal stability, Youngs modulus of 140 MPa and ultimate strength of 4 MPa. The degree of cross-linking of the realised fibres regulates their durability and degradation profile under conditions of high humidity, but also allows controlling the delivery over time of active agents encapsulated inside the fibres. We demonstrate that the N-methacrylate glycol chitosan nanofibres are able to release an antimicrobial drug within 24 hours. Moreover, cells proliferation of 85% indicates that non-cytotoxic substances were released from the electrospun mats.

Investigation of the electro-spinnability of alginate solutions containing gold precursor HAuCl4.

Alginate nanofibers with an average diameter of 75nm have been prepared by the electrospinning process. In addition, the spinnability of the solutions in the presence of the gold precursor HAuCl4 was investigated. At low concentrations of HAuCl4 well-formed nanofibers were produced, whereas as its concentration increases the nanofibrous mats present an increased number of bead-like defects. Herein, the in situ preparation of gold nanoparticles (Au NPs) is discussed since sodium alginate (SA) acts as the reducing agent and a mechanism is proposed in order to explain the bead-effect as well as the surface morphology of the alginate fibers decorated with Au NPs.

Alginate nanofibers with tunable biodegradability for regenerative medicine [Abstract]

This is an accompanying abstract of a poster presented at 4th TERMIS World Congress Boston, Massachusetts September 8–11, 2015. Final publication is available from Mary Ann Liebert, Inc., publishers https://www.liebertpub.com/doi/pdf/10.1089/ten.tea.2015.5000.abstracts

Spatially controlled proliferation, migration and differentiation of neural stem cells on novel 3D conductive scaffolds [Abstract]

This is an accompanying abstract of a poster presented at 4th TERMIS World Congress Boston, Massachusetts September 8–11, 2015. Final publication is available from Mary Ann Liebert, Inc., publishers https://www.liebertpub.com/doi/pdf/10.1089/ten.tea.2015.5000.abstracts

Mechanical Property of Poly (3-hydroxybutyrate)/Bioglass Nanocomposite Scaffolds for Bone Tissue Engineering

Because of the excellent osteoconductivity and high bioactivity of bioglass, particularly in the form of nanoparticles, poly (3-hydroxybutyrate)/bioglass nanocomposite scaffolds were prepared by using salt leaching process. The structures of scaffolds were analyzed by SEM, FTIR and DTA. The scaffolds were prepared in 3 different volume fractions of porosity (70, 80 and 90% wt% of salt particle) and 5 different wt% of bioglass nanoparticles (0, 2.5, 5, 7.5 and 10%). The tensile test results showed that with decreasing volume fraction of porosity and increasing bioglass nanoparticles, Young’s modulus and tensile strength of scaffolds were improved significantly. In conclusion, scaffolds were designed with wide range of mechanical property that can be used for bone tissue engineering.