R. Elghanian et al., SELECTIVE COLORIMETRIC DETECTION OF POLYNUCLEOTIDES BASED ON THE DISTANCE-DEPENDENT OPTICAL-PROPERTIES OF GOLD NANOPARTICLES, Science, 277(5329), 1997, pp. 1078-1081
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.