Sharif Digital Repository

Porosity and high surface area is a profound concept for creating advance materials. Nanofibers are an important class of nanomaterials with high surface to volume ratio as a result of long lengths and nano-to-micro-scale diameters. Electrospinning is a simple method for producing nanofibers from different polymers and composites and prepare highly efficient sorbents. Polymeric nanocomposites are claimed to exhibit markedly improved mechanical, magnetic, thermal and electrical properties. Magnetic iron oxide nanoparticles have gained great attentions due to their low toxicity, stability and biocompatibility and have been extensively used to induce magnetic property to the desired sorbents.... 

Novel electrospun nanofibers and their applications as the microextractionsorbents are the centre of this research. Polymeric nanofibers with diameter in the scale of nano-to-micro were prepared by the electrospinning method and employed for microextraction purposes. Two major microextraction methods included solid phase microextraction (SPME) and micro-Solid phase extraction (µ-SPE). In the first work, a novel SPME fiber was fabricated by electrospinning method. A thin stainless steel wire was coated by the network of polymeric nanofibers. The polymeric nanofiber coating on the wire was mechanically stable due to the fine and continuous nanofibers formation around the wire with a three... 

In the first work, a superhydrophobic polystyrene hollow fiber (PS–HF) was synthesized by electrospinning and used in microextraction of trazine herbicides from aquatic media followed by gas chromatography mass spectrometric (GC–MS) determination. Effects of different parameters influencing the extraction efficiency including the solvent extraction and its amount, the desorbing solvent and its amount, extraction time and ionic strength were optimized. The characteristic properties of the hollow fiber were studied by scanning electron microscopy (SEM). The limits of detection and quantification of the method under optimized condition were 2 and 6 ng L-1, respectively. The relative standard... 

Natural tissues of body consist of Extra Cellular Matrix (ECM) and cells. Scaffold produces a temporary matrix for cells and facilitates oxygen and nutrients transport which enhances tissue regeneration. Therefore, attempts in regeneration of tissues and organs by scaffolds attracted great interest in today’s researchs. Choosing scaffold fabrication method and its polymer type, play a key role in scaffold specifications as they determine scaffold properties. In this project electrospinning was chosen as the scaffold fabrication method which is because of the unique properties of scaffolds fabricated by this method and also its ability in producing micro and nano fibers. At first set of... 

In this research, an adsorptive affinity membrane has been prepared based on the combination of the nanofiber structure’s intrinsic characteristic in the dye adsorption and its membrane filtration properties. Electrospinning method has been used to prepare chitosan/poly(vinyl alcohol) (PVA) nanofibers. The morphology and properties of the prepared nanofibrous membranes were characterized using Fourier-transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (FE-SEM), image processing, atomic force microscopy (AFM), and thermogravimetric analysis (TGA). Also, the major drawback of electrospun nanofibrous membranes (ENMs) is their low mechanical resistance. So,... 

Acceleration of healing process for crucial wounds has been remained a challenging issue and it is critical to improve treatments against infection during wound healing period. Among various antimicrobial agents, silver components has been extensively since they are resistant against a wide range of bacteria. In this study, we developed electrospun mats composed of Polycaprolactone (PCL) and Polyvinyl alcohol (PVA) loaded with major silver components using co-electrospinnig method. Chitosan- Ag nanoparticles was synthesized using chitosan via heating prior to electrospinning. Various amounts of Silver components including Ag+, Silversulfadiazine (SSD) and Chitosan- Ag NPs were added to PVA... 

The aim of conducting this research is to study, fabrication and photocatalytic application of electrospun ZnO-based composite nanofibers. One of the most important challenges is to apply photocatalyst under solar irradiation and improve its activity for pollutant degradation. ZnO is a wide band gap semiconductor, hence, it is not active under the visible light. In Iran, we have at least 300 sunny days in a year. Therefore, fabrication and application of photocatalytic material with activity under the sunlight which contains 47% of visible light is so vital in our country. Since CuO is a visible light active photocatalyst and its interface with ZnO forms a type I heterojunction, this... 

In the present study we examined the fabrication of electrospun polymer drug delivery system for the production of polymeric film containing Rizatriptan drug. Fabricated films were underwent X-ray diffraction and DSC tests to ensure that the drug is not in crystalline and amorphous form. And the results revealed the fact that the drug is fully dispersed in the polymer. pH changes in the aqueous phase is too low so that it enable the polymeric film to be suitable for use in oral administration. In-vitro assay for different combination of sublingual polymeric suggested that Rizatriptan film with 3% weight by volume and 30% by weight by volume of electrospun polymer PVP is the best combination... 

Cardiovascular diseases are the leading cause of death all over the world, even more common than cancers. The first reason of mortality in Iran according to statistics is the occlusion of coronary arteries. Unfortunately almost one third of patients doesn’t have enough blood vessels to be used in the bypass surgery and need artificial vessels. These artificial blood vessels with small diameters (less than 6 mm) will fail quickly. As a result there is an increasing demand for tissue engineered blood vessels which are capable of enduring high blood pressures. An artificial blood vessel should mimic both structure and mechanical properties of the real one. Blood vessels have layered structures,... 

Cardiovascular disease is one of the most leading causes of death in the world and one of the common methods for treating such diseases is replacing damaged blood vessels with artificial ones. Electrospinning, which is a method of producing polymer fibers, is one of the best and common methods of producing synthetic vessels. The first goal in this study was to create a suitable structure for fiber production; therefore, first, an electrospinning device and environmental chamber were designed and built. Then, the effect of alternative and uniform flow on the diameter and structure of the fibers was investigated using 15% wt. Polycaprolactone solution. The results of this study showed that the... 

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.... 

Nerve damage is one of the factors affecting the quality of life of patients. The nervous system does not have the ability to repair large injuries, and autologous transplantation, which is the standard treatment method for nerve injuries, is faced with a shortage of donors and a decrease in the function of the donor site. Tissue engineering hydrogels, due to their similarity to the natural tissue of the stomatal body, are a hope for the repair of nerve tissue. In this research, an injectable, minimally invasive and temperature-sensitive hydrogel based on chitosan-etaglycerophosphate-sodium hydrogen carbonate salt or trisodium phosphate salt containing aligned nanofibers made of gelatin and... 

In recent decades, due to the significant growth of implants’ application and considering the infection of the implants as the most momentous factor in implantation failure, study on the controlled drug release and other biologically active agents in modern drug delivery systems has attracted many kinds of research throughout the world and efforts are being made to use regulated drug delivery systems for implantation which is also the purpose of this current scientific work.To achieve this, the anodizing process was used to fabricate titanium oxide nanotubes (TNTs) to increase the absorption capacity of the drug in the implants and these TNTs were formed regularly and uniformly in an organic... 

Nowadays, biocompatible composites are being utilized as scaffolds supporting cell growth promotion and features with the aim of organs regeneration or substitution based on tissue engineering principals. Moreover, in order to improve bioscaffolds features and function, various two-dimensional composite fillers have been under investigation; for instance, Graphene, Boron nitride, Metal dichalcogenides and oxides and black phosphorous and also electrospinning is mentioned as one of the most compatible and conventional processes of scaffold design that is also the main method of fabrication in this study. In addition, it should be pointed that biocompatible polymers and particularly natural... 

In this research, the synthesis of the electrospum nano fiber doped zinc oxide and its photocatalyst usage was investigated. The band gap of the zinc oxide in the area of UV leads to deactivation of this material at the visible light. With due the attention to sunny weather in Iran and the fact that about 50 percentage of sunlight is visible light, producing and usage of catalyst materials actived at visible light is economical. Doping is one of the ways of activating ZnO at visible light, so in this research thiourea is used as the source of ZnO doping. The results of the expriments done at visible light and also spectrums of DRS, XPS and XRD prove that the doping is happened. Also, in this... 

The aim of the present thesis was a synthesis of carbon nanofibers (CNFs) derived from electrospun poly vinyl alcohol (PVA) by means of various stabilizers and, moreover, improvement of synthetic CNFs with the incorporation of carbon nanotubes (CNTs). In order to do so, PVA solutions were prepared and electrospun with and without the cadmium salt. In order to do so, PVA solutions were prepared and electrospun with and without the presence of cadmium salt. The resultant polymeric nanofibers were carbonized directly and indirectly. In the case of indirectly carbonization, they were iodinated before the carbonization process. In the case of CNF-CNT composites, after having oxidized by nitric... 

The the nervous system as a most comlicated body system , plays an important and vital role for the body systems. damage to the peripheral nervous system result in nervous system disorders which claissified to Neuropraxia, Axonotmesis and Neurotmesis based on damage itensity. tissue engineering considered as one of the repairing nervous damage way, which by creating 3D substrat (scaffold) with proper physical structure, increses possibility of adhesion, growth and proliferation of cells to increase regeneration rate of damaged nerve. in this study, a combination of dual-electrospinning and rolling the spun film used to preparate a nerve guidance conduit (NGC) based on gelatin, PCL and... 

The main goal of this project is to fabricate the scaffolds including Polycaprolactone and Polyvinyle alcohol nanofibers in order to use as artificial skin. For this purpose, electrospinning parameters have been optimized for various injection rates and the scaffolds containing different percent of PCL and PVA have been made. By investigating the cell growth on these scaffolds, the one made up PVA/PCL (30% ) has been introduced as the best scaffold. To improve biological properties of chosen scaffold, a layer of collagen was coated. The angiogenesis capacity has been improved by adding Heparin to PVA nanofibers. Based on assay of heparin release, it was shown that Heparin is released within... 

In this research we focus on study and fabrication of ZnO composite nanofibers by electrospinning method for photocatalytic application. The most important challenges in the field of photocatalyst are photocatalytic activity under the visible light and efficiency enhancement. ZnO is a wide band gap semiconductor and it is not active under the visible light. In Iran, we have more than 300 sunny days in a year. Therefore fabrication and application of photocatalytic material with activity under the sun light that contained 40% of visible light is so vital in our country. In the first part of this project, ZnO-CNT nanofibers were fabricated and carbon doped in the crystal lattice of the ZnO.... 

Electrospinning is a simple and versatile technique for producing polymeric and ceramic nanofibers. The conventional procedure for fabrication of ceramic nanofibers is a combination of sol-gel techniques and electrospinning. The main challenge is the spin polymer nanofiber in fabricate of fibers with diameter from 1 to 100 nm, while their standard deviation are as low as possible. Uniform beads free polyamidenanofibers with lower diameter were fabricated.A 18% w/w of polyamide in formic acid was chosen and the effect of magnetic field, adding magnetic ionic liquid surfactant, auxiliary electrode on the main fiber were investigated. They termsfiber 1 to fiber 5. The mean diameters of 489,...