SERS-based DNA detection in aqueous solutions using oligonucleotide-modified Ag nanoprisms and gold nanoparticles.

Oligonucleotide-modified nanoparticle conjugates show highly promising potential for SERS-based DNA detection. However, it remains challenging to carry out the SERS-based DNA detection in aqueous solutions directly using oligonucleotide-modified nanoparticles, because the Raman reporters would exhibit lower signals when they are dispersed in aqueous solutions than laid on "dry" metal nanoparticles. Here, we synthesized stable oligonucleotide-modified Ag nanoprism conjugates, and performed SERS-based DNA detection in aqueous solution directly by using such conjugates in combination with Raman reporter-labeled, oligonucleotide-modified gold nanoparticles. The experimental results indicate that this SERS-based DNA detection approach exhibited a good linear correlation between SERS signal intensity and the logarithm of target DNA concentration ranging from 10(-11)∼10(-8) M. This sensitivity is comparable to those SERS-based DNA detection approaches with the "dry" process. Additionally, a similar correlation could also be observed in duplex target DNA detection by SERS hybrid probes. Our results suggest that the oligonucleotide-modified Ag nanoprisms may be developed as a powerful SERS-based DNA detection tool.