This project has explored the use of diamond-based sensors for biosensing applications. Diamond thin films offer an attractive platform for biosensing and bioelectronic applications, due to a unique set of physical, chemical, and electrochemical properties. The focus of this project has been i) the development of novel method for the functionalization of diamond surfaces, and ii) the development of highly sensitive diamond-based transducing electronic devices. Novel methods for introducing functional groups onto diamond surfaces have been developed based on self-assembled monolayers (SAMs) and polymer brushes. SAMs were shown to be suitable for the preparation of monolayers of proteins on diamond surfaces, whereas polymers brushes were shown to be effective for achieving a much higher loading of proteins. Polymer brushes were tailored in order to provide several functionalities, namely docking sites for protein immobilization and redox active groups to enhance charge transport along the insulating polymers. Several spectroscopy techniques confirmed the high loading of proteins on the polymer brush, as well as the effective electron charge transfer over large distances in the redox-functional polymers. The influence of the material properties, as well as the impact of the surface modification on the electron transfer across the diamond/protein and diamond/electrolyte interface has been the focus of this project. Arrays of diamond microelectrodes, as well as arrays of diamond field effect transistors have been developed during the time span of the project. Combining our functionalization efforts with the diamond sensors, we have demonstrated enzyme-modified amperometric diamond biosensors for the detection of H2O2, a molecule involved in neurotransmission regulation. In the last stage, the project has also address the potential use of graphene-related materials for sensing applications.
The project has exploited the interdisciplinary expertise brought into the IGSSE team by the group of Prof. R. Jordan (now Professur für Makromolekulare Chemie, TU Dresden), and the group of Dr. J.A. Garrido (Walter Schottky Institut, E25, TU München). During the time span of the project, the largest part of the work has been carried out by the doctoral candidates Ms. Naima A. Hutter (Chemistry Department) and Mr. Andreas Reitinger (Physics Department).