The development of new analytical approaches in the diagnostics of the diseases with higher throughput, smaller sample and set-up sizes, lower cost and easier disposal is one of the major needs of modern medicine. Miniaturization and simplification of biomedical assays are required for point of care diagnostics and lab-on-a-chip systems. In this thesis the concept of electrical biosensors based on single wall carbon nanotubes (SWCNTs) and graphene is presented. The detection of saccharides and DNA was realized using field effect transistor (FET) - based sensors where carbon nanostructures play the role of a transducing component.The theoretical part of the thesis explains the concept of biosensing and the role of nanomaterials in the development of the next generation of bioassays. Furthermore, the structure and properties of SWCNTs and graphene and their advantages for electrical biosensing are described.The experimental section starts with a detailed description of the carbon nanotube (CNT) biosensor fabrication process. This includes carbon nanotube solution preparation, assembly of CNTs into devices, passivation of metal electrodes and modification of the CNT surface with receptors. The advantages of using impedance spectroscopy measurements at different liquid gate voltages for electrical detection of biomolecules are pointed out here.The next chapter is dedicated to affinity-based glucose sensing. Using boronic acid functionalized carbon nanotubes the detection of glucose was demonstrated. The sensing mechanism was investigated in detail. The sensor signal was shown to be different depending on the way the CNTs were modified covalently or non-covalently.The biosensing setup was then utilized for the detection of DNA. It was possible to achieve very low limit of detection for oligonucleotides using CNTs non-covalently modified with a complementary DNA sequence. The sensor was shown to be highly selective as well. Finally, the possibility of using 2D-carbon nanomaterial, namely graphene, for electrical biosensing is outlined. The approaches towards large scale preparation of graphene devices were investigated during this work. The wafer-scale fabrication of reduced graphene oxide devices was realized using a novel chemical route.The final part of the thesis summarizes the results obtained while conducting this work. The designed biosensing platforms based on carbon nanostructures show a great promise for application in chemical analysis and medical diagnostics. Therefore the developed biosensor is planned to be adapted for the detection of analytes from biological liquids.
Verknüpfung zu Publikationen oder weiteren Datensätzen
