Selective colorimetric detection of polynucleotides based on the distance-dependent optical properties of gold nanoparticles

A highly selective, colorimetric polynucleotide detection method based on mercaptoal-kyloligonucleotide-modified gold nanoparticle probes is reported. Introduction of a sin-gle-stranded target oligonucleotide (30 bases) into a solution containing the appropriate probes resulted in the formation of a polymeric network of nanoparticles with a con-comitant red-to-pinkish/purple color change. Hybridization was facilitated by freezing and thawing of the solutions, and the denaturation of these hybrid materials showe