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 single-stranded target oligonucleotide (3 0 bases) into a solution containing the appropriate probes resulted in the formation of a polymeric network of nanoparticles with a concomit ant red-to-pinkish/purple color change. Hybridization was facilitated by freezing and thawing of the solutions, and the denaturation of thes e hybrid materials showed transition temperatures over a narrow range that allowed differentiation of a variety of imperfect targets. Transf er of the hybridization mixture to a reverse-phase silica plate result ed in a blue color upon drying that could be detected visually. The un optimized system can detect about 10 femtomoles of an oligonucleotide.