Abstract
Nartobiotransducers are biomolecules linked to nanostructures with the ability to generate a physical signal apon the occurrence of a molecular event of biological interest. In this paper we report the use of a diagnostic probe made of a specific oligonucleotide bearing a fluorescein at its 5'end and a 2 nm gold particle at its 3'end, which acts as a quencher. The nanobiotransducer performs as a molecular beacon and emits a stronger fluorescence signal when hybridised to target DNA. The advantage over conventional molecular beacons is that this approach does not require any sequence constraint, because the proximity between the emitter and the quencher is due to the physical adsorption of the fluorophore on gold and not to the formation of DNA hairpins.
The probe was used to confirm the identity of PCR amplifications obtained from DNA extracted from grapevine plants affected by flavescence doree. The nanob::otransducer detected all positive samples, although the quantitative results were not in strict agreement with the densitometry values obtained in parallel slot-blot membrane hybridisation experiments carried out with a biotin-labelled probe. This appears to be the first report of the use of a nanobiotransducer for the detection of an infectious agent in field samples.