Hybridisation of surface-immobilised single-stranded oligonucleotides and polymer monitored by surface plasmon resonance

We have investigated the hybridisation of thiol-modified single-stranded DNA embedded in a polyacrylamide layer through the technique of surface plasmon resonance (SPR). Kinetic studies were carried out by two different immobilisation methods: (a) SH-ssDNA was firstly attached on gold and the remaining free space was filled with polymer and (b) SH-ssDNA and the polymer was attached onto the surface from the same solution. The immobilisation methods were compared for various concentrations of SH-ssDNA. Hybridisation was dependent on both the immobilisation method and the concentration of the components. The highest hybridisation was obtained when SH-ssDNA and the polymer was immobilised from the same solution at low SH-ssDNA concentration or when high concentrations of oligos were spread onto the surface and the surface was posttreated with polymer. The target response corresponded to a surface coverage of 100 +/- 15 ng/cm(2). The same surface coverage on hybridisation was also obtained when low concentration of SH-ssDNA and polymer was attached onto the surface from the same solution. The non-specific binding. of sample DNA was very low at optimal concentrations due to the polymer and the hybridisation was linearly dependent on target concentration. (c) 2006 Elsevier B.V. All rights reserved.