A DNA duplex with extremely enhanced thermal stability based on controlled immobilization on gold nanoparticles.

The effect of DNA loadings on the thermal stability of DNA duplex immobilized on gold nanoparticles has been investigated. The modestly loaded duplexes on the gold nanoparticles showed enhanced thermal stability, as compared to that of the free duplex (without gold nanoparticles). However, the highly loaded duplex showed stability similar to that of free duplex. The stability could be controlled over a wide temperature range simply by varying the salt concentration (over 50 degrees C). Additionally, the gold nanoparticles with modestly loaded oligonucleotides could be used as nanoprobes for effective and fast strand exchange reactions, based on the increased thermal stability of the immobilized duplex. These results indicate that the interaction between the duplex and the nanoparticle surface plays an important role in determining the stability of the duplex.