DNA NANOSTRUCTURES AND BIOSENSORS: SOLUTIONS FOR SIGNAL AMPLIFICATION

Our goal is to develop signal enhancement strategies that could increase the sensitivity in DNA recognition by hybridization. These strategies can be used towards the realization of simple, economic, portable point-of-care detection devices, to be used for diagnostics or environmental monitoring. Hybridization Chain Reaction (HCR) is an isothermal polymerization process based on the formation of high-molecular weight double-stranded nucleic-acid structures triggered by the presence of a single-stranded oligonucleotide initiator[1]. Such polymerization needs only a limited number of oligonucleotides and no enzymes or other reactants, so it seems directly amenable of use in analytical assays. In our opinion, HCR could be a good candidate as signal amplification strategy. Here we report the results of a series of preliminary experiments that tested a possible implementation of the HCR as a surface-bound reaction. We verified the success of the chain reaction both by standard techniques such as gel electrophoresis and spectrofluorimetry and also by using chemo-electronic measurements amenable of miniaturization for microfluidic microfabricated biosensor implementation[2]. Our preliminary results already demonstrate a clear advantage in the biosensor read-out when the hybridization chain reaction is used as a pre-reading signal-enhancement step.