AVS 49th International Symposium
    Surface Science Wednesday Sessions
       Session SS-WeP

Paper SS-WeP10
Characterization of Functionalized Thiol-SA-Layers on Au using TP-SIMS and Polyatomic ToF-SIMS

Wednesday, November 6, 2002, 11:00 am, Room Exhibit Hall B2

Session: Surface Science Poster Session
Presenter: J.C. Feldner, Westfälische Wilhelms-Universität, Germany
Authors: M. Schröder, Westfälische Wilhelms-Universität, Germany
J.C. Feldner, Westfälische Wilhelms-Universität, Germany
S. Sohn, Westfälische Wilhelms-Universität, Germany
H.F. Arlinghaus, Westfälische Wilhelms-Universität, Germany
Correspondent: Click to Email
Functionalized monolayer substrates provide the basis for biosensor chips and other biorecognition systems. Several factors, such as type of SA layer building molecules, their functional headgroups and the different parameters concerning the immobilization process, influence the physical, chemical and biochemical properties of these substrate surfaces. We investigated different thiol classes, such as alkanethiols, C@sub n@H@sub 2n+2@S, alkanethiol derivatives and aromatic thiols, with different functional headgroups, e.g. NH@sub 2@, COOH or OH, immobilized onto Au-substrates. Thiols with functional headgroups could be linked to larger biomolecules such as DNA and proteins in order to design biosensor-chips for diagnostics. To link NH@sub 2@-terminated molecules to carboxyllated surfaces, we used 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide (EDC) to catalyze the formation of an amide bond. Another possibility for linking such molecules to a surface is to bind an NH@sub 2@-terminated thiol to the gold and use di-(n-succinimidyl)-carbonate (DSC) as a crosslinking mediator. The different reaction steps were monitored using time-of-flight secondary ion mass spectrometry (ToF-SIMS). We carried out ToF-SIMS measurements on SA-layers of different alkanethiols to investigate the time, concentration, and chain length dependence of the layer formation. Also, the influence of primary ion mass and of primary ion constituents on the secondary ion yield was investigated. With temperature-programmed SIMS (TP-SIMS), we were able to compare the desorption temperatures of different thiols, e.g. alkanethiols and their derivatives, and to investigate the influence of functional headgroups on the surface binding energy. From the obtained data it can be concluded that ToF-SIMS and TP-SIMS are useful techniques for investigating physical properties of SA-layers and for controlling crosslinking reactions to optimize e.g. binding conditions of DNA or PNA.