Sharif Digital Repository

In this research, fabrication of a mediator free nano-biosensor for the detection of cyanide has been studied. This biosensor utilizes 75 nm diameter (nano) ZnO particles synthesized with sol- gel method for modification and immobilization of Horseradish peroxidase (HRP). Cyanide plays inhibitory role in decomposition of H2O2 while HRP plays catalyst role in this reaction. Cyanide inhibits enzyme activity thorough binding with enzyme active sites and result in decreasing electrical current in electrochemical decomposition of H2O2. Amperometery response of biosensor shows linear relation between inhibition percent and cyanide concentration in range of 3µM - 24µM with detection limit of 0.62µM... 

Tissue engineering is a science that tries to create new tissues by using cells, growth factors and appropriate biological materials in order to repair damaged organs and replace parts lost due to various reasons. In this research, the effect of adding mxene sheets on the oxidized alginate-gelatin hydrogel scaffold was investigated. For this purpose, mxene nanosheets were first synthesized by Max phase chemical etching and its synthesis was confirmed by X-ray diffraction spectroscoy, field emission scanning electron microscope, X-ray energy diffraction spectroscopy, Fourier-transform infrared spectroscopy, UV-visible spectroscopy. Then, in order to prepare the scaffolds, different amounts of... 

After carbon and hydrogen the most existed element in crude oil is sulfur which is appeared as sulfur compound in fossil fuels. Sulfur might be converted to hydrogen sulfide by hydrodesulphurization operation. The increasing demand for sulfur removal has required large improvements in hydrodesulphurization technology.Most hydrodesulphurization processes use fixed-bed reactors, however, there are still some disadvantages with performing hydrodesulphurization in these reactors. The most important one is high exothermic nature of hydrodesulphurization process which cause some problems for catalyst in these reactors and decrease the performance of catalyst. In order to solve the temperature... 

Cardiovascular diseases are one of the leading causes of death worldwide. Despite significant advances in therapeutic interventions for these diseases, the pathophysiology remains incompletely understood. Challenges in drug evaluation include the lack of appropriate clinical trials, such as conventional 2D cell cultures and animal studies, as well as the absence of model systems that can provide complex and patient-specific cardiac functions for diagnosis. Organ-on-a-chip devices have the potential to mimic the body's response to treatments by utilizing microscale cell culture fluid connections and creating realistic models of human organs of interest. Our objective is to develop a... 

Once damaged, articular cartilage has very little capacity for spontaneous healing because of the avascular nature of the tissue. Although many repair techniques have been proposed over the past decades, none has successfully regenerated long-lasting tissue to replace damaged cartilage. Tissue engineering have recently demonstrated tremendous approaches for regeneration of cartilage tissue lesions. Tissue engineering is based on three principles: cells, scaffolds for cell adhesion and growth factors. Three-dimensional biodegradable scaffolds play an important role in tissue engineering. In this study, novel cross-linked hybrid chitosan/ECM scaffolds were prepared for articular cartilage... 

The purpose of this study is to assess the inhibitory effects of an appropriate nanoparticles loaded with gallic acid on the fibrillation of alpha-synuclein. Alpha-synuclein is a major component of protein plaques in synucleinopathies, particularly Parkinson’s disease. Gallic acid (GA, 3,4,5-trihydroxy benzoic acid) is a well–known small molecule which can inhibit the formation of α-synuclein fibrils. For the process of fibrillation, purified protein was incubated at 37◦C and pH 7.2. Fibrillation was analyzed by the standard fibril methods.after that investigated fabricating of gallic acid trapped in the chitosan nanoparticles and gallic acid loaded in chitosan –coated mesoporous silica... 

Currently, using biocompatible and injectable polymeric microcarriers as one of the efficient methods to transfer cells and active agents has gained much attention for bone regenerative medicine. However, they have some drawbacks such as weak mechanical stability and lack of mineral materials, which are the major ingredients of the bone tissues. Accordingly, it is expected that mimicking the chemical and physical structure of bone tissues could be valuable in their medical applications. Herein, a new porous biodegradable microcarriers (MCs) made of silk fibroin-oxidized alginate-bioactive glass was fabricated by electrospraying method. Response surface methodology (RSM) was used to study the... 

In this work, we have used a 3D printer and unidirectional ice-templating technique in conjunction, to fabricate a novel composite scaffold to facilitate local osteochondral defects tissue regeneration with a cell-free approach. Using ice-templating to induce radially-aligned porosity formation in type I bovine collagen is known to expedite host cells' migration into the scaffold which their ECM secretion shifts cellular milieu toward that of its neighboring tissue layer. We used numerical analysis to design and optimize appropriate freeze-casting mold, finding the optimum value for pin height and metal slab depth to be 4mm and 14mm, respectively. Collagen content equivalent to 2%w/v was... 

Cranioplasty is a surgical procedure for repairing skull defects. This surgery will protect the brain tissue, reduce pain in the lesion site and reduce the psychological burden on the patient. Cranioplasty implants should have distinct characteristics, i.e., high strength for protecting the brain, full coverage of skull defects, resistance to infection, non-expansion with heat, and reasonable price. Titanium implants, bone allografts, hydroxyapatite, and methyl methacrylate are commonly used in this surgery. However, these materials have many disadvantages that limit their use. As a result, biodegradable material and 3D printing technology are the next steps for designing scaffolds according... 

The nervous system is the most important communication machine in body which regulates the function of other organs. Peripheral nerves in contrary to central nervous system have the potential for regeneration, but regrowth requires proper environmental conditions and supporting growth factors. Tissue engineered scaffolds create a suitable milieu for disconnected axon to regenerate. The aim of this study in the first stage is the fabrication of nanostructured of conductive polymers (graphene and polyaniline) within a bed of gelatin polymer and then conducting some analyses including conductance, degradation rate and tensile test besides morphological analyses of fibers through SEM and... 

A system of electrospun scaffold containing drug-loaded chitosan nanoparticles was introduced for using in spinal cord tissue engineering. In spinal cord injury treatment, the formation of glial scar after injury which contains proteoglycans and activate glial cells should be avoided. In this study, the release of Dexamethasone sodium phosphate (DEXP) as a steroid anti-inflammatory agent from electrospun nanofiber composite containing chitosan nanoparticles was investigated. DEXP is believed to act through its glucocorticoid receptors found in most neurons and glial cells. These receptors’ pathways are involved in the inhibition of astrocyte proliferation and microglial activation.... 

In this project, a novel system of bioactive electrospun scaffold for bladder tissue engineering , has been investigated to control in vitro cell differentiation, and utilize in in vivo vascularization and tissue formation. This method doesn’t have custom bioactive scaffolds problems such as, protein instability, technical complexity and, difficulties in accurate kinetics prediction. First of all, protein loaded chitosan nanoparticles based on ionic gelation interaction between chitosan and Sodium tripolyphosphate were prepared. Maximum protein loading efficiency (80% for BSA & 99% for TGF-beta1) in chitosan nanoparticles was obtained at mean diameter of 51nm. Moreover polycaprolactone... 

Cartilage is an avascular tissue, having limited ability to repair itself. Since the methods for treatment of cartilage defects have been not effective, in recent years, new therapies based on tissue engineering are considered.This paper reports on the development of porous microcarriers composed of acellular matrix of cartilage and natural polymer chitosan. Microcarriers were prepared by electrospray method. Results of mechanical tests, SEM imaging, water uptake behaviour, biodegradation test, and MTT assay demonstrated that the microcarriers composed of 2% (wt) chitosan and 1% (wt) ECM has the best potential for growth and proliferation of primary chondrocyte cells. These results... 

Herein, we successfully prepared two types of hydrogels, alginate-beta-cyclodextrin based hydrogel and alginate without beta-cyclodextrin hydrogel in order to use in cartilage tissue engineering. At first, sodium alginate was modified with beta-cyclodextrin ring due to incorporate the kartogenin (KGN) differentiating drug in the hydrogel structure. For confirming the correctness of the modification reactions, H-NMR spectroscopy was used. In the presence of phenolized-ECM, alginic acid, modified alginate with beta cyclodextrin, HRP, H2O2, calcium carbonate, and glucono-delta-lactone (GDL), ECM-alginate-IPN and ECM-modified-alginate-IPN hydrogels were synthesized. Then, the KGN was loaded on... 

The retina, a photosensitive area in the central nervous system, is delicate and intricate. It is susceptible to degenerative disorders such as age-related macular degeneration (AMD), retinitis pigmentosa (RP), Stargardt disease (SD), and glaucoma. These diseases can lead to severe vision loss and ultimately irreversible blindness by causing destruction or dysfunction of different types of retinal cells. Unfortunately, there are no proven treatment strategies to cure or reverse these degenerative disorders. However, cell transplantation therapies may be an alternative to replace distorted cells and improve an individual's vision. Recent clinical outcomes show that transplanted cells in the... 

"osteoarthritis" is one of the most common joint diseases. This disease has a close relationship with factors such as aging, weight gain, genetics, mechanical pressures, and severe injuries. Although the mechanism of this disease is not fully understood, inflammation is one of the main causes of its exacerbation and progression. controlling inflammation can greatly help in controlling the disease. One of the common treatment methods for osteoarthritis is intra-articular injection of hyaluronic acid and triamcinolone as anti-inflammatory drug. Hyaluronic acid is the main component of synovial fluid, with its viscosupplementation property, prevents bones from rubbing against each other in the... 

Wound healing is a complex and regular process. It makes more challenge when the volume of wound exudate becomes uncontrollable. To solve this problem, hydrofiber wound dressings which contain carboxymethyl cellulose fibers are being used. Fast absorption and keeping the moisture in balance specially in chronic wounds, is one of the major features of hydrofiber wound dressings. In this research, which was conducted with the aim of investigating the synergy effect of active glasses and Hydrofiber commercial wound dressing for the healing of skin wounds, especially chronic wounds, the sol-gel method has been used to synthesize bioactive glasses based on borosilicate, replacing a part of CaO... 

Despite the increase in the number of cardiovascular diseases worldwide, the number of new drugs to treat these diseases has been decreasing in the last decade. Current preclinical drug evaluation strategies, which use cell cultures and oversimplified animal models, cannot meet the growing demand for new and effective drugs. In the last decade, the development of microfluidic bioreactors and organ-on-chip systems to improve the drug screening process has been increasing significantly. These systems have shown many advantages over previous preclinical models. Despite all these advantages, keeping the oxygen concentration at the optimal physiological level in microfluidic systems has its own... 

Nowadays, advanced and inexpensive pre-clinical methods for investigating the effects of anti-cancer drugs are expanding. One of the latest three-dimensional laboratory modeling for evaluating the effects of drugs is the use of tumor-on-chip technology, which actually models the physiological system of the body through three-dimensional scaffolds, multicellular cultures, and shaped vascular systems. In this study, three-dimensional culture of cancer cells was performed in the form of spheroids. A chip of U-shaped microstructures with and without gaps was used to trap cells and form cancer spheroids. We simulated the simultaneous effect of drug and oxygen concentration distribution inside the... 

Death can be the result of severe bleeding which is associated with the loss of a high amount of blood like what happens in accidents, wars, or operations. Classic methods to stop bleeding are mostly ineffective to decrease the hemostasis time and the volume of the lost blood. A wide variety of products like powders, foams, and hydrogels have been designed and synthesized either from natural or synthetic polymers. However, limitations like weak tissue adhesion, creating a moist environment in the wound site, infection, weak biodegradation, and hemolysis still have remained. Among the existing options to be used as hemostasis agents, polysaccharides can be appropriate considering their great...