Selective Colorimetric Detection of Polynucleotides Based on the Distance-Dependent Optical Properties of Gold Nanoparticles

TLDR

The study presents a selective colorimetric method for detecting polynucleotides using mercaptoalkyloligonucleotide‑modified gold nanoparticles. Target oligonucleotides (30 bases) hybridize to the probes via freeze‑thaw cycles, forming polymeric nanoparticle networks that shift the solution color from red to purple, and after transfer to a reverse‑phase silica plate the dried complexes display a blue color for visual detection. The prototype detects as low as ~10 femtomoles of oligonucleotide.

Abstract

A highly selective, colorimetric polynucleotide detection method based on mercaptoalkyloligonucleotide-modified gold nanoparticle probes is reported. Introduction of a single-stranded target oligonucleotide (30 bases) into a solution containing the appropriate probes resulted in the formation of a polymeric network of nanoparticles with a concomitant red-to-pinkish/purple color change. Hybridization was facilitated by freezing and thawing of the solutions, and the denaturation of these hybrid materials showed transition temperatures over a narrow range that allowed differentiation of a variety of imperfect targets. Transfer of the hybridization mixture to a reverse-phase silica plate resulted in a blue color upon drying that could be detected visually. The unoptimized system can detect about 10 femtomoles of an oligonucleotide.