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    Biomaterials Friday Sessions
       Session BI-FrM

Paper BI-FrM3
TOF-SIMS Analysis of Nucleic Acid Biosensor Chips

Friday, November 2, 2001, 9:00 am, Room 102

Session: Biosensors
Presenter: H.F. Arlinghaus, Universität Münster, Germany
Authors: H.F. Arlinghaus, Universität Münster, Germany
M. Ostrop, Universität Münster, Germany
O. Friedrichs, Universität Münster, Germany
J.C. Feldner, Universität Münster, Germany
Correspondent: Click to Email
In recent years DNA-chip-technology has been a subject of growing interest for clinical diagnostics as well as for DNA sequencing and forensic. DNA-chips are based on the method of sequencing by hybridization (SBH), where unknown DNA fragments are hybridized to complementary oligodeoxynucleotides (ODN) which are immobilized on a solid surface in an array format. The main variables in SBH are the attachment of the nucleic acid sequences to a solid surface, the conditions for hybridization, and the detection of the hybridized DNA sequences. We have used TOF-SIMS to examine in detail the immobilization process of PNA/ODN and to investigate its ability to detect DNA-fragments hybridized to complementary PNAs. For this purpose we immobilized either silane SA-layers on silicon wafers or DTSP SA-layer on Ag or Au surfaces. PNA and DNA of different concentrations were then bound to these layers. Deprotenated (M-H)@super -@ signal of the different ODN and PNA bases as well as phosphate ions were used to monitor the ODN/PNA concentration. It was found that the immobilization process is strongly dependent on concentration and immobilization time. Under optimized conditions, PNA can be covalently bound to these surfaces. The homogeneity of the immobilized PNA depends on the evaporation time of the PNA solution. After optimizing the immobilization process, complementary and non-complementary DNAs were hybridized to the PNA biosensor chip. Hybridized DNA could be readily identified by detecting the PO@sub 2@@super -@ and PO@sub 3@@super -@ masses. A good discrimination between complementary and non-complementary sequences could be achieved. It can be concluded that TOF-SIMS is a very useful techniques for investigating the complexity of the immobilization and hybridization processes and that SIMS has the potential for providing a rapid method for DNA/RNA sequencing and diagnostics. .