Hybridization of binary monolayers of single stranded oligonucleotides and short blocking molecules

We have studied the immobilization of single stranded (ss) DNA oligonucleotides of 16–27 base pairs on gold. The oligonucleotides were thiol-modified (SH-ssDNA) or disulfide-modified via a dimethoxytrityl-group (DMT-S-S-ssDNA). Immobilization was performed by adsorption of the probes on the gold sur...

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Bibliographic Details
Published in:Surface science 2009-02, Vol.603 (4), p.620-624
Main Authors: Vikholm-Lundin, Inger, Auer, Sanna, Munter, Tony, Fiegl, Heidi, Apostolidou, Sophia
Format: Article
Language:English
Subjects:
Condensed matter: electronic structure, electrical, magnetic, and optical properties
Condensed matter: structure, mechanical and thermal properties
Cross-disciplinary physics: materials science
rheology
Exact sciences and technology
Hybridization
Immobilization
Oligonucleotides
Physics
Self-assembly
Surface plasmon resonance
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Summary:We have studied the immobilization of single stranded (ss) DNA oligonucleotides of 16–27 base pairs on gold. The oligonucleotides were thiol-modified (SH-ssDNA) or disulfide-modified via a dimethoxytrityl-group (DMT-S-S-ssDNA). Immobilization was performed by adsorption of the probes on the gold surface for 10–15 min, a time within which saturation coverage was obtained for both thiol- and disulfide-modified probes. Hereafter the layer was post-treated with hydroxyalkyl substituted lipoamides also for a time of 10–15 min. The surface density of layers with shorter probes (16–18 mer) was twice (2.4 ± 0.2 × 10 13 probes/cm 2) that of the longer probes (25–27 mer) as studied with surface plasmon resonance. Hybridization of single stranded polymerase chain reaction (PCR) amplified products with a length above 300 base pairs gave a very low hybridization response. For amplicons with about 100 base pairs the response was high. The surface coverage was comparable to that of complementary ssDNA binding (3.0 × 10 12 strands/cm 2). Surfaces made from SH-ssDNA showed a 30% higher hybridization response than surfaces made from DMT-S-S-ssDNA. The PCR amplified products used are of relevance in breast cancer diagnosis. The results clearly demonstrate that the single stranded PCR products might be used in label-free cancer diagnostics.
ISSN:0039-6028
1879-2758
DOI:10.1016/j.susc.2008.12.026