Sharif Digital Repository

The aim of this dissertation is to investigate and determine the optimal composition of hydrogels that can meet the needs of stem cells for the growth and proliferation of mesenchymal stem cells. In this research, firstly, unfunctionalized and functionalized mesoporous silica nanoparticles (with an average diameter of approximately 90 nm), were synthesized. Scanning electron microscopy and zeta potential measurement were utilized to study their morphology and surface charge. Then, graphene oxide nanosheets were synthesized. Field emission electron microscopy, zeta potential measurement and Fourier transform infrared spectrum analysis were used to examine their morphology, surface charge and... 

Probiotics are defined as essential live microorganisms that, when administered in adequate amounts, confer a health benefit on the host. In order to provide health benefits for probiotic bacteria it has been recommended that they must be present at a minimum level of 106 CFU/g of food product or 107 CFU/g at point of delivery or be eaten in sufficient amounts to yield a daily intake of 108 CFU. Several studies have shown that certain strain of lactic acid bacteria, such as Bifidobacterium bifidum and Lactobacillus acidophilus prevent some diseases linked to the gastro-intestinal tract. however, many reports have demonstrated their poor survival and stability. Their survival in the... 

Type 1 diabetes, formerly known as insulin-dependent diabetes, may present at any age, but is the most common type of diabetes affecting children and adolescents. People with type 1 diabetes do not produce enough insulin. This type accounts for 5-10% of all types of diabetes. In this type of diabetes, beta cell destruction occurs in the pancreas. In type 1 diabetes, the pancreas does not secrete any insulin; insulin is a hormone that enables the body to convert glucose in food into energy. If sugar in the blood cannot enter the cells, it accumulates in the arteries and results in high blood sugar. High blood sugar over time can have irreversible effects on various parts of the body. Curcumin... 

Bone is one of the most vital parts of the body for almost any functional movement. Due to its many involved diseases, traumas and injuries, bone maintenance and regeneration are of high importance. Engineering and design of complex tissues, with impeccable mimicry of the native ones, are always accounted as the solution to dysfunction of body organs due to aging, various diseases, etc. However, the inability to complete mimicry of the native tissue architecture and cell microenvironment are the main barriers to functional tissue regeneration. In this project, in order to design a suitable scaffold for bone regeneration, hydrogel nanocomposites with polysaccharide basis were developed by... 

Vitamin C is an essential for the survival of human, animals and plants. Human and most animals can not produce vitamin C in their bodies, thus the need to produce vitamin C as a supplement is necessary. Nowadays, for the industrial production of vitamin C, two Chinese and Rychstyn methods are used, the first method is a two-step method which is accomplished biological and the second method is done chemically. In Chinese method, first step, which is the most important step is production of L-sorbose from D-sorbitol by Gluconobacter oxydans bacteria .Thus, in this study it was attempted to optimize the production of L-sorbose to be used in industrial production of L-ascorbic acid. In... 

Microbial proteases are among the most important hydrolytic enzymes and havebeen studied extensively since the advent of enzymology. They are essentialconstituents of all forms of life on earth, including prokaryotes, fungi, plants andanimals.In recent years there has been a phenomenal increase in the use of alkaline protease asindustrial catalysts. Alkaline proteases (EC.3.4.21–24, 99) are defined as thoseproteases which are active in a neutral to alkaline pH range. Cell immobilization is a technique that restricts the free movements of microorganisms in the process and it has a lot of advantages including this fact that biotechnologists’ dream for using continuous system in fermentation...