An immobilisation procedure based on the direct coupling of thiol-derivatised oligonucleotide probes (Probe-C6-SH) to bare gold sensor surfaces has been optimised for DNA sensing applications. The instrumentation used were the commercially available instruments BIACORE XTM and SPREETATM based on surface plasmon resonance (SPR) and a quartz crystal microbalance (QCM).
The performances of the DNA-based sensors resulting from direct coupling of thiol-derivatised DNA probes onto gold SPR-chips or electrodes of quartz crystals, have been studied in terms of the main analytical parameters, i.e. selectivity, sensitivity, reproducibility, analysis time, etc.
A comparison between the thiol-derivatised immobilisation approach and a reference immobilisation method, based on the coupling of biotinylated oligonucleotide probes onto a streptavidin coated dextran sensor surface, using synthetic complementary oligonucleotides has been discussed in detail.
The DNA biosensors developed have been also used to test DNA samples amplified by polymerase chain reaction (PCR).