Functionalization of diamond surfaces for biosensor applications

• Applicants: Professor Dr. Jose A. Garrido; Professor Dr. Rainer Jordan
• Subject Area: Measurement Systems
• Term: from 2007 to 2013
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 51175491

This project will explore the functionalization of diamond surfaces for the development of enzyme-based biosensors. Due to its chemical inertness and biocompatibility, diamond surfaces provide unique properties for the direct integration of biochemical and electronic systems. A stable C-C-bonding between the diamond substrate surface and the functionalized layer including the attached biomolecules can be implemented using our recently developed chemical modification of diamond surfaces by means of self-assembled monolayers (SAMs) of aromatic diazonium salts. Here, the mechanism of the grafting reaction as well as important aspects of the self-assembly of the aryl derivatives into the SAM will be studied as a function of different ^-substitutions. This will allow the preparation of diamond surfaces with a variety of chemical functional groups and surface properties. Moreover, the density as well as lateral localization of functional groups for bioactive site attachment will be adjusted by the formation of homogenous, mixed, as well as patterned SAMs. In addition, surfaceinitiated polymerization techniques using the aromatic SAMs as 2D initiators templates will be employed to prepare polymer brushes on diamond surfaces. The multiplicity of polymer bonded functional groups will significantly improve the sensitivity of the biosensor devices. The project aims at the integration of the grafting technology with electronic biosensing devices based on the diamond structures. Here, two different transducing techniques will be developed: i) Diamond electrode arrays for amperometric detection and ii) Field effect pH and ion-sensors to exploit the inherent sensitivity of these devices to local changes of charge and pH. For both transducing techniques, orientation, density, and distance to substrate of grafted biomolecules will be tuned by means of our well controlled surface chemistry.

• DFG Programme: Research Grants