Monitoring denaturation behaviour and comparative stability of DNA triple helices using oligonucleotide-gold nanoparticle conjugates.

Gold nanoparticle labels, combined with UV-visible optical absorption spectroscopic methods, are employed to probe the temperature-dependent solution properties of DNA triple helices. By using oligonucleotide-nanoparticle conjugates to characterize triplex denaturation, for the first time triplex to duplex melting transitions may be sensitively monitored, with minimal signal interference from duplex to single strand melting, for both parallel and antiparallel triple helices. Further, the comparative sequence-dependent stability of DNA triple helices may also be examined using this approach. Specifically, triplex to duplex melting transitions for triplexes formed using oligonucleotides that incorporate 8-aminoguanine derivatives were successfully monitored and stabilization of both parallel and antiparallel triplexes following 8-aminoguanine substitutions is demonstrated.