A new approach for the detection of DNA sequences in amplified nucleic acids by a surface plasmon resonance biosensor

In this paper, a simple and useful approach for DNA sensing based on surface plasmon resonance (SPR) transduction is reported. A new DNA sample pre-treatment has been optimised to allow fast and simple detection of hybridisation reaction between a target sequence in solution and a probe immobilised on the sensing surface. This pre-treatment consisted in a denaturation procedure of double stranded DNA containing the target sequence and was based on an high temperature treatment (95 degrees C, 5 min) followed by a 1 min incubation with small oligonucleotides. The oligonucleotides are designed to prevent the re-hybridising of the denatured strands, while enabling the target sequence to bind the immobilised probe. The important parameters of the procedure, i.e. incubation time, length and concentration of the oligonucleotides, have been studied in detail. The optimised DNA denaturation procedure has been successfully applied to the detection of amplified DNA with a commercially available SPR biosensor (Biacore X). DNA samples extracted from plant and human blood were tested after amplification by polymerase chain reaction (PCR).