Jhaleh Amirian

Bone formation of a porous Gelatin-Pectin-biphasic calcium phosphate composite in presence of BMP-2 and VEGF.

A composite scaffold of gelatin (Gel)-pectin (Pec)-biphasic calcium phosphate (BCP) was fabricated for the successful delivery of growth factors. Bone morphogenetic protein-2 (BMP-2) and vascular endothelial growth factor (VEGF) were coated on the Gel-Pec-BCP surface to investigate of effect of them on bone healing. Surface morphology was investigated by scanning electron microscopy, and BCP dispersion in the hydrogel scaffolds was measured by energy dispersive X-ray spectroscopy. The results obtained from Fourier transform infrared spectroscopy showed that BMP-2 and VEGF were successfully coated on Gel-Pec-BCP hydrogel scaffolds. MC3T3-E1 preosteoblasts were cultivated on the scaffolds to investigate the effect of BMP-2 and VEGF on cell viability and proliferation. VEGF and BMP-2 loaded on Gel-Pec-BCP scaffold facilitated increased cell spreading and proliferation compared to Gel-Pec-BCP scaffolds. In vivo, bone formation was examined using rat models. Bone formation was observed in Gel-Pec-BCP/BMP-2 and Gel-Pec-BCP/VEGF scaffolds within 4 weeks, and was greatest with Gel-Pec-BCP/BMP-2 scaffolds. In vitro and in vivo results suggest that Gel-Pec-BCP/BMP-2 and Gel-Pec-BCP/VEGF scaffolds could enhance bone regeneration.

HAp granules encapsulated oxidized alginate-gelatin-biphasic calcium phosphate hydrogel for bone regeneration.

Bone repair in the critical size defect zone using 3D hydrogel scaffold is still a challenge in tissue engineering field. A novel type of hydrogel scaffold combining ceramic and polymer materials, therefore, was fabricated to meet this challenge. In this study, oxidized alginate-gelatin-biphasic calcium phosphate (OxAlg-Gel-BCP) and spherical hydroxyapatite (HAp) granules encapsulated OxAlg-Gel-BCP hydrogel complex were fabricated using freeze-drying method. Detailed morphological and material characterizations of OxAlg-Gel-BCP hydrogel (OGB00), 25wt% and 35wt% granules encapsulated hydrogel (OGB25 and OGB35) were carried out for micro-structure, porosity, chemical constituents, and compressive stress analysis. Cell viability, cell attachment, proliferation and differentiation behavior of rat bone marrow-derived stem cell (BMSC) on OGB00, OGB25 and OGB35 scaffolds were confirmed by MTT assay, Live-Dead assay, and confocal imaging in vitro experiments. Finally, OGB00 and OGB25 hydrogel scaffolds were implanted in the critical size defect of rabbit femoral chondyle for 4 and 8 weeks. The micro-CT analysis and histological studies conducted by H&E and Massons trichrome demonstrated that a significantly higher (***p<0.001) and earlier bone formation happened in case of 25% HAp granules encapsulated OxAlg-Gel-BCP hydrogel than in OxAlg-Gel-BCP complex alone. All results taken together, HAp granules encapsulated OxAlg-Gel-BCP system can be a promising 3D hydrogel scaffold for the healing of a critical bone defect.

Graphene oxide/Fe3O4/SO3H nanohybrid: a new adsorbent for adsorption and reduction of Cr(VI) from aqueous solutions

A sulfonated magnetic graphene oxide (SMGO) hybrid was successfully synthesized via the nucleophilic substitution reaction and characterized. The removal of chromate by SMGO was investigated. The effects of contact time, initial pH of the solution, and initial chromate concentration on the removal efficiency were investigated. The optimal experimental conditions for enhanced chromate removal were found to be a contact time of 60 min at an initial solution pH of 3. The observed data were fitted with Lagergren pseudo-second-order kinetic model, indicating that chromate adsorption on SMGO was a chemical interaction in nature. The Langmuir model was also used to describe the adsorption processes and the adsorption capacity was found to be 222.22 mg g−1. Thermodynamic studies (ΔG 0, ΔS > 0) revealed that the adsorption process was exothermic and spontaneous. SMGO has potential to be applied several times after desorption in wastewater treatment.

In vitro and in vivo evaluation of effectiveness of a novel TEMPO-oxidized cellulose nanofiber-silk fibroin scaffold in wound healing

In this study, a novel TEMPO-oxidized cellulose nanofiber (TOCN)-silk fibroin scaffold was prepared using a cost effective freeze drying method. Fundamental physical characterizations were carried out by scanning electron microscopy (SEM), pore diameter determination, FT-IR. PBS uptake behavior of the scaffold showed that, silk fibroin can enhance the swelling capacity of TOCN. L929 primary fibroblast cell was selected for in vitro studies, which showed that the scaffolds facilitated growth of cells. In vivo evaluation of TOCN, TOCN-silk fibroin composites was examined using critical sized rat skin excisional model for one and two weeks. The results of rat wound model revealed that, compared to only TOCN scaffold, TOCN-silk fibroin scaffold successfully promoted wound healing by the expression of wound healing markers. TOCN-silk fibroin 2% has the fastest wound healing capacity. Thus, it appears that TOCN-silk fibroin composite scaffolds can be useful as wound healing material in clinical applications.

Oxidative desulfurization of model oil in an organic biphasic system catalysed by Fe3O4@SiO2–ionic liquid

Lewis or Bronsted acidic methylimidazolium ionic liquid-functionalized Fe3O4@SiO2 nanoparticles were fabricated and applied as an efficient magnetic heterogeneous catalyst for dibenzothiophene (DBT) oxidation in a biphasic system using H2O2 as the oxidant. The structures of catalysts were characterized by SEM, TEM, XRD, TGA, FT-IR, VSM and EDX techniques. The magnetic catalysts showed high catalytic performance in the oxidation of DBT in an n-hexane/acetonitrile biphasic system using H2O2, and high conversions were obtained. The effects of contact time, temperature, amount of H2O2 and amount of catalyst on the DBT oxidative removal efficiency were investigated. The contact time of 60 min, 0.1 g catalyst, and 4 mL H2O2 at 313 K were found as optimal experimental conditions for an improved DBT oxidative removal process. The sulfur level could be lowered from 100 ppm to less than 7, 5, and 2 ppm under optimal conditions for Fe3O4@SiO2–Mim-BF4, Fe3O4@SiO2–Mim-HSO4, and Fe3O4@SiO2–Mim–FeCl4, respectively. These nanomagnetic heterogeneous catalysts could be easily separated from the reaction mixture by applying an external magnetic field and recycled several times.

Preparation and characterization of polycaprolactone–polyethylene glycol methyl ether and polycaprolactone–chitosan electrospun mats potential for vascular tissue engineering:

Recently, natural polymers are frequently comingled with synthetic polymers either by physical or chemical modification to prepare numerous tissue-engineered graft with promising biological function, strength, and stability. The aim of this study was to determine the efficiency for vascular tissue engineering of two distinctly different mats, one that comprised polycaprolactone–polyethylene glycol methyl ether and other that comprised polycaprolactone–chitosan. Nano/microfibrous mats prepared from electro-spinning were characterized for fiber diameter, porosity, wettability, and mechanical strength. Biological efficacy on both biodegradable mats was assessed by rat bone marrow mesenchymal stem cells, and polycaprolactone–polyethylene glycol methyl ether showed feasibility for use as an inner layer by inducing endothelial-specific gene expression and polycaprolactone–chitosan as an outer layer on dual layered without sacrificing tensile strength, small-diameter blood vessels. Therefore, scaffolds fabricated from this research could be potential sources for tissue-engineered vascular graft and could also overcome the well-known drawbacks, such as thrombogenicity and stenosis, in managing vascular disease.

Examination of In vitro and In vivo biocompatibility of alginate-hyaluronic acid microbeads As a promising method in cell delivery for kidney regeneration

In this study, alginate (ALG) and alginate-hyaluronic acid (ALG-HA) injectable microbeads, with the purpose of delivering stem cells for tissue engineering, were prepared by a spraying method into a CaCl2 solution that shows high porosity for the exchange of nutrition and waste. In addition, the size distribution and surface morphology was investigated using optical and scanning electron microscopy, respectively. The chemical structural properties of the ALG-HA microbeads were examined by Fourier transform infrared spectroscopy. The biocompatibility of ALG and ALG-HA microbeads was examined in vitro. Rat bone marrow stem cells were encapsulated in microbeads to investigate cell release, cell viability, proliferation, and secretion of growth factors such as VEGF and PDGF. Growth factors were released for the 21day experimental period. Cells were found to be released from the microbeads after 7days. Furthermore, the in vivo biocompatibility of ALG-HA microbeads was examined using microbeads without cell encapsulation in the kidney capsule, in order to assess the foreign body reaction and inflammatory response, for 14days. The desired in vivo response to ALG-HA microbeads hydrogel makes it an exquisite candidate for subcapsular cell and drug delivery to kidney tissue.