AVS 47th International Symposium
    Biomaterial Interfaces Thursday Sessions
       Session BI+NS-ThA

Paper BI+NS-ThA5
Silicon Surface Chemistry for DNA Immobilization

Thursday, October 5, 2000, 3:20 pm, Room 202

Session: Biosensors
Presenter: R.J. Hamers, University of Wisconsin, Madison
Authors: T. Strother, University of Wisconsin, Madison
Z. Lin, University of Wisconsin, Madison
W. Cai, University of Wisconsin, Madison
L.M. Smith, University of Wisconsin, Madison
R.J. Hamers, University of Wisconsin, Madison
Correspondent: Click to Email
Many emerging areas of biotechnology, such as "gene chips", seek to leverage many aspects of the existing infrastructure in microelectronics and apply it to new areas. While most previous work has focused on the attachment of DNA to surfaces of gold or glass, we have investigated the chemistry involved in covalently bonding DNA to Si(001) and Si(111) surfaces in a way that retains its ability to selectively hybridize with its solution-phase complements. The use of XPS to study the chemical structure at each step in the DNA attachment process has lead to the development of new procedures that are both simple and robust. Starting with hydrogen-terminated Si(001) and Si(111) surfaces, photochemical excitation at 254 is used to remove the photo-labile hydrogen; the exposed surface is then reactive toward organic molecules containing one or more unsaturated C=C bonds. "Linker" molecules containing a C=C double bond with another functional group(such as an amine or ester group) are then used to provide a dense set of surface-bound functional groups for attachment of DNA. To control the selectivity of the attachment process, however, careful optimization of the molecular structure of the linker and the other processing conditions are required. The density and chemical uniformity of the surface (as judged by XPS) is highly correlated with the intensity and selectivity achieved in subsequent binding of the surface-bound DNA to its fluorescently-labeled complements in solution. The results show that control of surface chemistry indeeds leads to significant improvements in the formation of DNA-functionalized silicon surfaces.