Sharif Digital Repository

This thesis activities, consists of three main parts. The first part is, manufacturing and optimization of the electrical part of blood glucose measurement devices, based on electrochemical sensors. In this part, design of blood glucose measurement systems based on two and three electrode electrochemical sensors are proceeded and the accuracy of the electrical block, is increased up to 1mg/dl according to sensor current range. The second part, is related to the design of different probes for blood electrical characteristics (impedance magnitude) measurements, at low frequencies. Measurements with these probes show, first the blood impedance magnitude range at low frequencies and moreover,... 

The first study of the present research aims to the possibility of developing simple, accurate and selective potentiometric sensors for the detection of scandium ions in aqueous solution, which is done for the first time. In this study, a sensor array consisting of 17 miniaturized potentiometric sensors based on polymeric membranes containing various ion-extracting ligands were designed and fabricated. Ligands as the active component of the membranes included phosphine oxides and diamides of various organic acids, which were used in the extraction of rare earth metal ions. The possibility of using these extractants in the polymer matrix of membranes for the development of scandium-sensitive... 

Hexavalent chromium ions (Cr(VI)) is one of the most dangerous heavy ions for the environment, humans and other living organisms. Hence, finding new ways to determine and reduction to the much less toxic trivalent chromium (Cr(III)) is highly important. In this thesis, electrochemical and photoelectrochemical methods have been employed for the direct detection and reduction of Cr (VI). For this purpose, the indium tin oxide (ITO) electrode decorated with gold-palladium bimetallic nanoparticles (AuPd) was used for the determination and reduction of Cr(VI) via electrochemical route. These AuPd decorated electrodes exhibited a wide linear concentration range of 0.001-100 µM, a very low... 

Recent years have witnessed an increasing interest in graphene and graphene-based materials due to their extraordinary electrical properties, large specific surface area, fascinating mechanical properties, good chemical stability and remarkable electrochemical activity. The combination of these properties make graphene an attractive candidate for a wide range of applications including energy conversion and storage devices (batteries and supercapacitors), electronic devices (transistors and memory devices) and solar cells. On the other hand, graphene has a potential application in constructing different kind of sensors such as biosensors and electrochemical sensors due to its planar... 

Thyroid gland is one of the important internal organs of the body that is responsible for T3 and T4 hormones secretion. Concentration of these hormones directly influences growth of body, thus measurement concentration of thyroid hormones is one of the most common experiments all of the world, specially in our country that Hypothyroidism is common among people. Secretion of hormones in thyroid gland controlled by TSH (thyroid Stimulating Hormone) that released from Pituitary gland. TSH concentration is opposite of level of thyroid secretion. Because of interconnected relationship between these three hormones, measurement of each of them is so important. Many researches for developing... 

Electrochemical sensing of glucose has received paramount attention in recent years, particularly, the non-enzymatic glucose sensing is one of the trends in the whole biosensing world. In this research, synthesis and evaluation of a hybrid structure of vertical oriented nickel nanorod-reduced graphene oxide sheets as a non-enzymatic glucose sensor were performed. The 3D array of nickel nanorods was synthesized by electrodeposition of nickel sulfate electrolyte in track-etched polycarbonate template with 100 nm pore size and 6-10 μm thickness. The electrodeposition performed in various conditions, and the best result was achieved by application of potential of 3 V for 60 minutes. The shiny... 

In the first part, a novel electrochemical sensor for clonazepam (CLNP) was fabricated based on immobilizing cellulose nanofibers /carbon nanoparticles (CNFs/CNPs) nanocomposite on glassy carbon electrode (CNFs/CNPs/GCE). The combination of CNFs and CNPs produced a novel kind of structurally uniform and electro-analytically active nanocomposite. The surface morphology of CNFs/CNPs layer deposited onto glassy carbon electrode was characterized by scanning electron microscopy. The results of the voltammetric investigations showed a considerable enhancement in the cathodic peak current of CLNP (up to 60 times) on the surface of CNFs/CNPs/GCE relative to the bare GCE. Under the optimal... 

In the recent years, conductive polymers are widely used in the design and construction of chemical and biological sensors.The polypyrrole due to features such as good thermal and chemical stability, ease of synthesis and better conductivity than other conductive polymers, atracts much attention. In order to modification of electrode surface,adhesiveand thin polymer films can be electropolymerized in the presence of organic or inorganic dopants on the surface of metal or carbon surfaces in aqueous or organic solutions. On the other hand carbon nanotubes by owing unique properties such as chemical stability and high electrical conductivity are good choice for electrod surface modification.... 

At the first part of this thesis, a pyrolitic graphite electrode (PGE) modified with graphite/nanodiamond film (GND) was applied as a sensitive electrochemical sensor for determination and study of electrochemical behavior of tryptophan (Trp) and 5-hydroxytryptophan (5-HTP) in aqueous solutions. The results showed that GND caused a remarkable increase in the peak currents so the GND/PGE electrode surface was more sensitive to the concentration of Trp and 5-HTP than the PGE surface. The determination of Trp and 5-HTP were investigated by stripping voltammetry. Experimental parameters such as scan rate, pH, accumulation conditions and amount of the modifier used on the PGE surface were...