Surface Implementation of the Hybridization Chain Reaction Towards the Enhancement of DNA Biosensors Signal

Our goal is to test simple strategies to attain high signals from DNA hybridization events. 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 is an isothermal polymerization process. In this, the formation of high-molecular weight double-stranded nucleic-acid structures is triggered by the presence of a single-stranded oligonucleotide initiator (Dirks and Pierce 2004). 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 the preliminary experiments that we present in this poster, we tested a possible implementation of the hybridization chain reaction as a surface-bound reaction. The chain reaction is triggered by a surface DNA hybridization event, such as those involved in the recognition between a surface-bound probe oligonucleotide and a soluble analyte nucleic acid. As our current interest goes towards label-free detection strategies, 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. Charged-based capacitance measurement of DNA hybridization is amenable of miniaturization for microfluidic microfabricated biosensor implementation (Guiducci, Stagni et al. 2004). Our still unoptimized results demonstrate a clear advantage in the biosensor read-out when the hybridization chain reaction is used as a pre-reading signal-enhancement step.