Nanostructuring metal-carbon composites for electrochemical biosensors

High performance electrochemical sensors are capable of detecting various biosignals and molecules from biological samples. Particularly, certain analytes with very low concentration within body fluids such as hydrogen peroxide, nitric oxide or heavy metal ions are difficult to be detected. To fabricate electrochemical sensors, novel materials with excellent electrochemical properties are required. Nanostructured carbon-metal composite materials have high performance for electrochemical sensing. While some metal or metal oxide nanoparticles are good at catalysis of analytes, carbon based materials such as graphene and nanotubes are excellent electron-conducting template. Nanocomposites can synergize the properties of various individual nanomaterials, giving rise to materials with enhanced performance and interesting properties. Nanostructuring refers to methods to form small nanoscale particles into high surface area three dimensional networks. Various forms of nanostructuring of these composite materials are explored in this thesis, with carbon based materials as starting template followed by nanostructuring using metal or metal oxides for electrochemical sensors. Namely, electrochemical deposition of gold nanoparticles onto reduced graphene oxide sheets, chemical functionalization between graphene nanosheets and gold nanoparticles, hydrothermal growth of metal oxides onto carbon nanotubes. Through these explorations, a flexible electrode formed by carbon nanotubes is fabricated and gold nanoparticles grown onto the electrode in situ for enzymatic immobilization and detection of glucose. In brief, this research project covers nanostructured metal and carbon composite materials’ synthesis and characterization, utilizing them for electrochemical sensor. By combining these different materials, it is aimed to achieve higher sensitivity and performance, as well as allowing the better understanding on the fundamentals of electron transfer and redox reactions on electrochemical biosensing.DOCTOR OF PHILOSOPHY (SCBE