DNA hybridization assays using metal-enhanced fluorescence

We describe a new approach to DNA hybridization assays using metal-enhanced fluorescence. Thiolated oligonucleotides were bound to silver particles on a glass substrate. Addition of a complementary fluorescein-labeled oligonucleotide resulted in a dramatic time-dependent 12-fold increase in fluorescence intensity during hybridization. Proximity to silver particles resulted in a decreased fluorescence lifetime. This effect is thought to be the result of enhanced fluorescence from fluorescein near metallic silver particles. Hybridization could thus be measured from the decay kinetics of the emission, which can be measured independently from the emission intensity. These results suggest the use of silver particles as a general approach to measure DNA hybridization as a method to increase the sensitivity of DNA detection.