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The Role of Metals in Electrochemical Sensors
In this study we investigated the role of metals in electrochemical biosensors. These roles can be studied form three different prospective: role of metals as an analyte of interest (Chapter 2 and 3), role of metals as a mediator (Chapters 4 and 5), and role of metals as an electrocatalyst (Chapter 6 and 7). Pertaining to the first role, we showed that biosensors can be used as specific tools for fast and accurate quantification of metal ions in biological and environmental samples. Concerning the second role, we used the unique characteristics of metal ions to make the sensors sensitive toward levels of other analytes. Regarding the third role, we used metals as electrocatalysts to increase the rate of electrochemical reactions and enhance the sensitivity of detection. Chapter 1 describes a brief introduction about biosensors, analytes of interest and the electrochemical techniques used in sensor interrogation. In Chapter 2, application of a peptide-based sensor derived from the calcium-binding site of E-cadherin was discussed for detection of Pb(II) in drinking water. In chapter 3, fabrication of an aptamers-based sensor for direct detection of Cd(II) in saliva is discussed. In chapter 4, we fabricated a DNA-based electrochemical sensor for detection of glutathione. In this sensor, Hg(II) was used as a complexing agent to increase sensor sensitivity toward glutathione levels. In chapter 5, we designed a sensor for detection of levofloxacin. In this sensor, Fe(III) was used as a mediator where it worked both as a redox reagent and a co-complexing agent. In chapter 6, we used Cr(VI) as a homogeneous electrocatalyst for electrochemical DNA sensing. By catalytic reactivity of Cr(VI) with Leucomethylene blue, we converted conventional "signal-off" electrochemical DNA sensors to "signal-on" and improved sensitivity of detection. In chapter 7, we used silver nanostructures as a heterogeneous electrocatalyst for direct reduction and detection of nitrate on the surface of ultramicroelectrodes in environmental samples. Chapter 8 covers dissertation conclusion and future direction.
Lotfizadehzhad, Hamidreza, "The Role of Metals in Electrochemical Sensors" (2018). ETD collection for University of Nebraska - Lincoln. AAI10793107.