Sharif Digital Repository

A hybrid scaffold of gelatin-glycosaminoglycan matrix and fibrin (FGG) has been synthesized to improve the mechanical properties, degradation time and cell response of fibrin-like scaffolds. The FGG scaffold was fabricated by optimizing some properties of fibrin-only gel and gelatin-glycosaminoglycan (GG) scaffolds. Mechanical analysis of optimized fibrin-only gel showed the Young module and tensile strength of up to 72 and 121 KPa, respectively. Significantly, the nine-fold increase in the Young modulus and a seven-fold increase in tensile strength was observed when fibrin reinforced with GG scaffold. Additionally, the results demonstrated that the degradation time of fibrin was enhanced... 

Porous scaffolds composed of gelatin/poly (vinyl alcohol), (Gel/PVA), were prepared using combination of freeze gelation and freeze drying methods. The effect of polymer concentration, gelatin/PVA ratio, and glutaraldehyde/gelatin ratio (GA/Gel) was investigated on morphology of pores, swelling ratio, biodegradation, and skin cell culture. At optimum preparation conditions the scaffolds had uniform pore size distributions showing high swelling ratio of 23.6. The scaffolds were of biodegradable nature and almost degraded in 28 days. Human dermal fibroblast cells (HDF) were cultured on the scaffolds and MTS assay was conducted to evaluate the influence of PVA on growth and proliferation of the... 

Modern techniques for expanding stem cells play a substantial role in tissue engineering: the raw material that facilitates regeneration of damaged tissues and treats diseases. The environmental conditions and bioprocessing methods are the primary determinants of the rate of cultured stem cell proliferation. Bioceramic scaffolds made of calcium phosphate are effective substrates for optimal cell proliferation. The present study investigates the effects of two bioceramic scaffolds on proliferating cells in culture media. One scaffold was made of hydroxyapatite and the other was a mixture of hydroxyapatite and ferromagnetic material (Fe3O4 nanoparticles). Disk-shaped (10 mm × 2 mm) samples of... 

Super-paramagnetic iron oxide nanoparticles (SPIONs) are recognized as powerful biocompatible materials for use in various biomedical applications, such as drug delivery, magnetic-resonance imaging, cell/protein separation, hyperthermia and transfection. This study investigates the impact of high concentrations of SPIONs on cytotoxicity and cell-cycle effects. The interactions of surfacesaturated (via interactions with cell medium) bare SPIONs and those coated with poly(vinyl alcohol) (PVA) with adhesive mouse fibroblast cells (L929) are investigated using an MTT assay. The two SPION formulations are synthesized using a co-precipitation method. The bare and coated magnetic nanoparticles with... 

Biocompatible porous polymeric scaffolds provide a suitable environment for proliferation of stem cells in human body. In this research work, porous gelatin–poly(ethylene glycol), PEG, based scaffolds were prepared using combination of freeze-gelation and freeze-extraction methods. Effects of various parameters such as freezing temperature, cross-linking agent, concentrations of gelatin and PEG and their blending ratio on physical and mechanical properties, swelling ratio, porosity, pore size, and degradation rate of scaffolds were investigated. Also, proliferation of fibroblast skin cells on the scaffolds was examined by MTS assay to assess the suitability of the scaffolds in wound healing... 

Superparamagnetic iron oxide nanoparticles (SPIONs) are increasingly used in medical applications, such as targeting delivery and imaging. In the future, patients are more likely to be exposed to pharmaceutical products containing such particles. The study of toxicity of SPIONs has become of great importance in recent years, although the published data in this arena is limited. The aim of the present work is to investigate the cytotoxicity of SPIONs and the effect of the particles on the cell medium components. For this purpose, uncoated and polyvinyl alcohol (PVA) coated SPIONs with narrow size distribution were synthesized via a well-known coprecipitation method. The mouse fibroblast cell... 

Herein, a hybrid hydrogel/microsphere system is introduced for accelerated wound healing by sustained release of basic fibroblast growth factor (bFGF). The hydrogel is composed of a mixture of PVA, gelatin and chitosan. The double-emulsion-solvent-evaporation method was utilized to obtain microspheres composed of PCL, as the organic phase, and PVA, as the aqueous phase. Subsequently, various in-vitro and in-vivo assays were performed to characterize the system. BSA was used to optimize the release mechanism, and encapsulation efficiency in microspheres, where a combination of 3% (w/v) PCL and 1% (w/v) PVA was found to be the optimum microsphere sample. Incorporation of microspheres within... 

Background: Unique properties of graphene and its derivatives make them attractive in the field of nanomedicine. However, the mass application of graphene might lead to side effects, which has not been properly addressed in previous studies, especially with regard to its effect on the cell cycle. Methods: The effect of two concentrations (100 and 200 μg/mL) of nano-and microsized graphene oxide (nGO and mGO) on apoptosis, cell cycle, and ROS generation was studied. The effect of both sizes on viability and genotoxicity of the embryonic fibroblast cell cycle was evaluated. MTT and flow cytometry were applied to evaluate the effects of graphene oxide (GO) nanosheets on viability of cells.... 

Porous scaffolds composed of gelatin/poly (vinyl alcohol), (Gel/PVA), were prepared using combination of freeze gelation and freeze drying methods. The effect of polymer concentration, gelatin/PVA ratio, and glutaraldehyde/gelatin ratio (GA/Gel) was investigated on morphology of pores, swelling ratio, biodegradation, and skin cell culture. At optimum preparation conditions the scaffolds had uniform pore size distributions showing high swelling ratio of 23.6. The scaffolds were of biodegradable nature and almost degraded in 28 days. Human dermal fibroblast cells (HDF) were cultured on the scaffolds and MTS assay was conducted to evaluate the influence of PVA on growth and proliferation of the... 

Abstract: In recent years, temporary skin grafts (TSG) based on natural biopolymers modified with carbon nanostructures have received considerable attention for wound healing. Developments are required to improve physico-mechanical properties of these materials to match to natural skins. Additionally, in-deep pre-clinical examinations are necessary to ensure biological performance and toxicity effect in vivo. In the present work, we show superior acute-wound healing effect of graphene oxide nanosheets embedded in ultrafine biopolymer fibers (60 nm) on adult male rats. Nano-fibrous chitosan-based skin grafts crosslinked by Genepin with physico-mechanical properties close to natural skins were... 

Nanoparticles for biomedical use must be cytocompatible with the biological environment that they are exposed to. Current research has focused on the surface functionalization of nanoparticles by using proteins, polymers, thiols and other organic compounds. Here we show that inorganic nanoparticles such as titanium oxide can be coated by pyrolytic carbon (PyC) and that the coating has cytocompatible properties. Pyrolization and condensation of methane formed a thin layer of pyrolytic carbon on the titanium oxide core. The formation of the PyC shell retards coalescence and sintering of the ceramic phase. Our MTT assay shows that the PyC-coated particles are cytocompatible at employed doses  

A single step supercritical method was introduced for synthesis of “magnetite - reduced graphene oxide (M-rGO)” composite in supercritical methanol. Modified surface, smaller size, lesser cytotoxicity, and homogenous dispersion of Fe3O4 nanoparticles on the graphene surface were advantages of this new M-rGO composite in comparison to the materials synthesized by conventional wet chemical method (M-GO). Nanocomposites were injected in tissue equivalent phantoms of agarose gel in 10 mg/g dosage, and were irradiated by a 1600 mW laser beam at wavelength of 800–810 nm. The M-rGO and M-GO were found to be the most and the least efficient samples for increasing the temperature of the phantom. As... 

Background: Extensive full-thickness burns require replacement of both epidermis and dermis. In designing skin replacements, the goal has been to re-create this model and make a product which has both essential components. Methods: In the present study, we developed procedures for establishing confluent, stratified layers of cultured human keratinocytes on the surface of modified collagen-chitosan scaffold that contains fibroblasts. The culture methods for propagation of keratinocytes and fibroblasts isolated from human neonatal foreskin were developed. The growth and proliferation of normal human keratinocytes were evaluated in serum-free (keratinocyte growth medium) and our modified... 

Scar tissue size following myocardial infarction is an independent predictor of cardiovascular outcomes, yet little is known about factors regulating scar size. We demonstrate that collagen V, a minor constituent of heart scars, regulates the size of heart scars after ischemic injury. Depletion of collagen V led to a paradoxical increase in post-infarction scar size with worsening of heart function. A systems genetics approach across 100 in-bred strains of mice demonstrated that collagen V is a critical driver of postinjury heart function. We show that collagen V deficiency alters the mechanical properties of scar tissue, and altered reciprocal feedback between matrix and cells induces... 

Graphene/cobalt nanocomposites are promising materials for theranostic nanomedicine applications, which are defined as the ability to diagnose, provide targeted therapy and monitor the response to the therapy. In this study, the composites were synthesized via chemical method, using graphene oxide as the source material and assembling cobalt nanoparticles of 15 nm over the surface of graphene sheets. Various characterization techniques were then employed to reveal the morphology, size and structure of the nanocomposites, such as X-ray diffraction analysis, X-ray photoelectron spectroscopy, Fourier transform infrared spectroscopy, high resolution transmission electron microscopy and... 

Hypothesis: It is now being increasingly accepted that cells in their native tissue show different morphologies than those grown on a culture plate. Culturing cells on the conventional two-dimensional (2D) culture plates does not closely resemble the in vivo three-dimensional (3D) structure of cells which in turn seems to affect cellular function. This is one of the reasons, among many others, that nanoparticles uptake and toxicology data from 2D culture plates and in vivo environments are not correlated with one another. In this study, we offer a novel platform technology for producing more in vivo-like models of in vitro cell culture. Experiments: The normal fibroblast cells (HU02) were... 

Metal-organic framework (MOF) based graphene oxide (GO) recently merits of attention because of the relative correspondence of GO with metal ions and organic binding linkers. Furthermore, introducing the GO to the Co-MOF to make a new nanoporous hybrid have are improved the selectivity and stability of the Co-MOF. Here the graphene oxide/cobalt metal organic framework (GO/Co-MOF) was synthesized by a solvothermal process using cobalt salt and terephthalic acid and used for biocidal activity, against the growth of the Gram-negative Escherichia coli and Gram-positive Staphylococcus aureus bacteria. X-ray diffraction, Fourier transform infrared spectroscopy and Raman spectroscopy were confirmed... 

In the current study, two series of antimicrobial dressings conjugated with silver sulfadiazine (SSD) and silver nanoparticles (AgNPs) were developed and evaluated for chronic wound healing. Highly porous polycaprolactone (PCL)/polyvinyl alcohol (PVA) nanofibers were loaded with different concentrations of SSD or AgNPs and compared comprehensively in vitro and in vivo. SSD and AgNPs indicated a strong and equal antimicrobial activity against S. aureus. However, SSD had more toxicity against fibroblast cells over one week in vitro culture. An in vivo model of wound healing on male Wistar rats was developed with a full thickness wound. All the wound dressings indicated enough flexibility and...