AVS 47th International Symposium
    Biomaterial Interfaces Wednesday Sessions
       Session BI-WeP

Paper BI-WeP12
TOF-SIMS Characterization of Nucleic Acid Biosensors

Wednesday, October 4, 2000, 11:00 am, Room Exhibit Hall C & D

Session: Poster Session
Presenter: H.F. Arlinghaus, Physikalisches Institut der Universität Münster, Germany
Authors: H.F. Arlinghaus, Physikalisches Institut der Universität Münster, Germany
M. Ostrop, Physikalisches Institut der Universität Münster, Germany
O. Friedrichs, Physikalisches Institut der Universität Münster, Germany
U. Gunst, Physikalisches Institut der Universität Münster, Germany
Correspondent: Click to Email
In recent years, biosensors consisting of immobilized oligodeoxynucleotides (ODN) have been a subject of growing interest for DNA sequencing and clinical diagnostics. We have used static TOF-SIMS and temperature-programmed SIMS (TP-SIMS) to examine in detail the immobilization process of ODNs, which were directly bound to Au- and Ag-surfaces by thyol-linkers. Protonated (M+H)@super +@ and deprotonated (M-H)@super -@ signals of the different ODNs and bases as well as phosphate ions were used to monitor the ODN concentration. The influence of ODN concentration and immobilization time on the immobilization process was investigated. It was found that the maximum intensity for characteristic ODN peaks was obtained using a 1 µM solution and an immobilization time of 24 h. According to our estimate, the surface coverage under these conditions should be close to a monolayer. Measurements of how surface structure affects the process of immobilization showed a higher intensity of the characteristic ODN signals and a less homogeneous oligonucleotide layer with increasing surface roughness. TP-SIMS was used to measure the thermal stability of the immobilized layers. The data show that the characteristic ODN fragment ions start to decrease at a temperature of about 150° C, with differences in the point of onset for the different bases. It can be concluded that the combination of TOF-SIMS and TP-SIMS is a powerful technique to examine the complexity of the immobilization and hybridization processes of nucleic acid.