Sharif Digital Repository

With the rapid development of biotechnology, peptide and protein drugs are now playing an increasingly important role in therapeutics. Compared with chemical drugs, peptide and protein drugs have some limitations such as low stability and rapid deactivation. Biodegradable and biocompatible polymeric micro carriers have been shown to have a high potential for the delivery of peptides and proteins. Among these polymers, alginate has been widely investigated as a biomaterial. Alginates are natural polysaccharide polymers isolated from brown seaweed. Bovine serum albumin (BSA) loaded calcium alginate microspheres produced in this study by a modified w/o emulsification method. The influence of... 

In this project, cellulose acetate butyrate (CAB) nanofibrous membranes in order to separate the contaminants of an industrial wastewater were prepared. Electrospinning process that is an effective method to fabricate nanofibers was used to prepare the membranes. Since various parameters affect this process and fibers morphology, optimization of these parameters is necessary for preparation of improved membranes. So the effect of parameters of solvent system, polymer concentration, applied voltage, distance between the tip of needle and collector, and rotational speed of collector on morphology and diameter of the nanofibers was investigated. Scanning electron microscopy (SEM) and image... 

Due to the negative effects of conventional plastics on the environment, especially in the packaging sector, extensive efforts have been put to replace these polymers with biodegradable polymers. Starch is one of the biodegradable polymers which has attracted a lot of attentions because of low cost and good process ability. Native starch has the form of granule and can be processed to a continuous phase after gelatinization in the presence of a plasticizer. The resulting material is a biodegradable plastic-like material called thermoplastic starch (TPS) which is processed using conventional technologies, but suffers from low mechanical properties and high hydrophilicity. Addition of... 

There are many industries in the world that produce colorized wastewater. Because of the complex structure and good solubility of dyes, such industries have problem treating this wastewaters. On the other hand, because of the toxicity of these materials for water living, dye removal from discharged wastewater of these industries is very important. In recent years, researchers have become interested in the synthesis of dye Nano adsorbents and they have published many works on this subject. The important parameters in the synthesis of such adsorbent include; non-toxicity, high adsorption capacity and easy separation. In this project, cellulose was extracted from bagasse and then CMC was... 

In this study, mesh-reinforced cellulose acetate (CA)-based membranes were prepared for forward osmosis (FO) by immersion precipitation. Casting composition, preparation conditions, evaporation time, coagulation bath temperature, annealing temperature, CA percent and 1,4-dioxane/acetone ratio were tested for membranes’ performance. Also, the results were compared with commercially CTA membranes. The FO membrane prepared under optimized conditions had a smooth surface similar to commercial ones. The most proper membrane (17.9 % polymer and 1,4-dioxane /acetone ratio 1.89) showed water flux of 9.3 L/m2.hr (LMH) and RSF of 0.536 mol NaCl/m2.hr. Using mesh in the membrane structure, different... 

Chronic wounds are among the serious injuries which have called the attention of scientists to invest in an effort to fabricate temporary skin grafts and wound dressing materials. One of the widely acceptable solutions to this obstacle is to design a bioactive scaffold capable of regenerating tissue as well as delivering active agents to the site specific area. To this end, natural biopolymers are considered as suitable candidates to be employed in regenerative medicine due to their excellent biocompatibility. In addition, nanoparticles possess special properties such as the ability in sequestering the drug release which make them promising candidates in the fabrication of the... 

Tissue regeneration by bio-compatible/degradable scaffolds is one of the widely used approaches in the field of tissue engineering. In this study, a thermoplastic starch based nanocomposite scaffold with gradient structure was fabricated by unidirectional freeze drying method. To increase the stability of the scaffold in the aqueous media, PVA was added to starch solution. Then, the PVA and starch molecules were cross-linked by adding citric acid to the mixture. On the one hand, to improve the mechanical properties of the scaffold, and control its bio-degradability on the other, cellulose nano-fibers were employed. Also, the bioactivity of the scaffold was induced by using hydroxyapatite... 

It is a common method to use some proper materials such as honey, herbal fibers, and minerals for covering the wounds as an effective treatment. Nowadays biopolymers and new methods of nanofiber production to build a structure similar to the natural extracellular matrix (ECM) like electrospinning are used to reduce the time of restoration and prevent from the effects of wounds such as bedsores, diabetic ulcers, and severe burns. For effective design of a wound dressing, wound feature, recovery time, physical, mechanical, and biological properties should be considered in order to best as possible heal the bound. In this research, cellulose nanocrystals with average aspect ratio of 11.8 and... 

Wound is a defect or failure in the skin texture which occurs as a result of physical or heat injuries or physiological conditions. The wound dress as a temporary cover can improve wound healing process and due to the unique properties, hydrogels have become appropriate choice for this application. Hydrogel’s structure allows drug to be loaded in the wound dress. Hydrogel wound dress should have adequate fluidity to cover wound’s bed and make full contact with the skin. Sufficient cohesion and strength is also necessary to allow the wound dress to remove from wound completely. Therefore, the study on the viscoelastic properties of hydrogel is important. In this study, polyvinyl alcohol... 

In this work, wool keratin/polyethylene oxide (PEO) nanofibrous scaffolds were fabricated by electrospinning method. Bacterial cellulose nanofibrils (BCNFs) were embedded in the electrospun keratin/PEO nanofibers. Incorporation of BCNFs into the nanofibers enhances their hydrophilicity, mechanical properties and cell viability, adhesion and proliferation. Water contact angle of the nanofibers decreased from 126˚ to 83˚by addition of 1 wt % BCNFs. A thermogelling hydrogel based on carboxylated pluronic (Pl-COOH) and gum tragacanth (GT) was fabricated and polymer conjugation was confirmed by FTIR and H-NMR spectroscopy. Morphological and viscoelastic properties of GT-grafted Pl-COOH hydrogels... 

Hydrogels are crosslinked hydrophilic polymers that are capable of imbedding large amounts of water or biological fluids usually to equilibrium. Because of their unique properties, these materials have become ubiquitous and indispensable materials in many applications in recent years. Synthetic methods have produced numerous hydrogel materials with excellent properties. However, their nonbiodegradability might pose long-term environmental problems and limit their use. As a consequence, various research groups have put considerable amounts of effort and resources toward development of new absorbent materials from natural polymers such as polysaccharides. In this research, new hydrogel... 

The efficiencies of perovskite solar cells have increased rapidly in recent years and reached about 22%. Which hopes to make this type of solar cell more functional. In the normal structure of perovskite solar cells, the presence of mesoporous TiO2 mesoporous layer has increased sustainability and efficiency. To create this layer, a common method is placing the sample in a furnace for 30 minutes at 450°C-500°C. Using the furnace, in addition to being time consuming, has a high energy consumption. In this study, we tried to create a TiO2 mesoporous layer with the help of lighting. To create TiO2 mesoporous layer, What causes porosity in the layer is the removal of ethyl cellulose and create... 

Fabrication and characterization of different surface charged cellulose electrospun scaffolds including cellulose acetate, cellulose, carboxymethyl cellulose and quaternary ammonium cationic cellulose for biomedical applications have been reported in this research. We describe preparation of cellulosic nanofibers through the electrospinning following deacetylation cellulose acetate. Moreover, surface modification of electrospun cellulose nanofibers is carried out to obtain carboxymethyl cellulose and quaternized cellulose nanofibers, respectively. At last, the structural, morphological, mechanical, swelling, wettability and the cell culture properties of the scaffolds were analyzed and... 

In this project, all-cellulose nanocomposites for smart packaging of meat products were synthesized via film casing method. These nanocomposites were aimed to provide visual response to pH change, which occurs due to decay of the meat products. The prepared nanocomposites would be placed inside the packages to be in direct contact with the products and could improve shelf life the products with the help of antibacterial natural extracts incorporated in the samples.Synthesis of the samples started with cellulose nano whiskers synthesis via acid hydrolysis. The prepared nanoparticles were then characterized with XRD, DLS, and Zeta potential analysis. It was shown that a big portion of the... 

One of the methods for adsorption of natural gas that has economical, operational and environmental preferences as an alternative energy source is storage as an adsorbed phase in porous material. ANG is superior to CNG and LNG technologies in terms of economy and safety. Carbonaceous nanostructures with pore diameter of 0.8-1.4 nm can be proper adsorbents for methane adsorption. In this work, cellulose and lignin which form lignocellulosic material’s structure, has been used as precursor for producing activated carbon. The activated carbon prepared has been used as adsorbent for adsorption of methane. The use of hydrothermal pretreatment followed by carbonization and chemical activation is... 

Nowadays, water pollution and water sources decreasion, is one of the important issues of our world. Treatment of polluted water and wastewater and recycling of those to industries and common uses, is very necessary. Dyes, is one of the biggest parts of water pollutants, especially, in textile plants. There are some ways for dye removal, in the industries; including biological, chemical and physical methods. Among of these methods, physical removal of dyes through adsorption (with Activated Carbon or other adsorbents), is very popular. Hydrogels are three-dimensional hydrophilic polymer networks, introducing very good swelling rate, mechanical properties and pollutants adsorption. In this... 

In this research, the characteristics of non-Newtonian, shear-thinning drop formation containing surfactant from a needle are investigated experimentally. The ambient fluid is air and all experiments have been conducted in a constant flow rate of drop phase fluid. Images of forming drop are taken using a high-speed camera and by processing them, important parameters in drop formation such as length of drop, minimum neck thickness, formation time and the size of satellite drops have been studied. Three non-Newtonian and three Newtonian fluids are considered in a way that the initial viscosity of non-Newtonian fluids would be equal to the viscosity of their corresponding Newtonian fluids.... 

Natural gas (NG) has emerged as an alternative energy source in transportation sector as it provides clean combustion and hence lowers exhaust pollution. NG can be stored as an adsorbed phase in porous materials and is referred to ANG. The use of adsorbent materials for storing NG, at relatively low pressure (3.5–4 MPa), is a possibility for making ANG technology competitive with CNG. Among all adsorbents, carbon nanostructures with pore diameter (0.8-1.4 nm) has shown the highest adsorption capacity of natural gas. In the present study, cellulose has been used as the carbonaceous precursor and Activated Carbon (AC) has been prepared using hydrothermal carbonization of cellulose followed by... 

TiO2 is one of the most frequently used photocatalyst materials. Porous TiO2 nanostructure has drawn much attention recently due to high decomposition rate of organic pollutants. In this thesis, TiO2 nanoparticles were synthesized via sol-gel method and were coated on cotton and jute fiber separately; besides, the impregnated fibers were heat treated to eliminate cellulose. Titanium tetraisopropoxide (TTIP) was used as a precursor and two solutions, acidic and alcoholic, were used as the primary solutions for synthesis. In acidic solution, the crystalline phase and size distribution of TiO2 nanoparticles were evaluated with changing pH.Then, the appropriate pH was chosen for coating. In... 

Nowadays bioethanol is one of the main factors in the fuel market. It is currently produced from sugars and starchy materials, but lignocelluloses can be expected to be major feedstocks for ethanol production in the future. Agricultural residues such as wheat straw are being considered a potential lignocellulose raw material for fuel-ethanol production as an alternative to starch or sugar-containing feedstock. In order to produce bioethanol, it is necessary to decompose the wheat straw into soluble sugars. But lignocellulosic materias needs pretreatment before hydrolysis and fermentation. The main goal of pretreatment is to increase the enzyme accessibility improving digestibility of...