Label-free colorimetric detection of specific sequences in genomic DNA amplified by the polymerase chain reaction.
We document the surprising result that single-stranded DNA adsorbs on negatively charged gold nanoparticles (Au-nps) with a rate that depends on sequence length and temperature. After ss-DNA adsorbs on Au-nps, we find that the particles are stabilized against salt-induced aggregation. These observations can be rationalized on the basis of electrostatics and form the basis for a colorimetric assay to identify specific sequences and single nucleotide polymorphisms on polymerase chain reaction (PCR)-amplified DNA. The assay is label-free, requires no covalent modification of the DNA or Au-np surfaces, and takes on the sensitivity of PCR. Most important, binding of target and probe takes place in solution where hybridization occurs in less than 1 min. As an example, we test PCR-amplified genomic DNA from clinical samples for single nucleotide polymorphisms (SNPs) associated with a fatal arrhythmia known as long QT syndrome.
Li
Huixiang
H
Contribution from the Department of Chemistry, Center for Future Health, University of Rochester, Rochester, NY 14627, USA.
Rothberg
Lewis J
LJ
D003124:Colorimetry / Q000379:methods*; D004277:DNA, Single-Stranded / Q000032:analysis* / Q000737:chemistry / Q000235:genetics; D017979:Gold Colloid / Q000737:chemistry; D016133:Polymerase Chain Reaction / Q000379:methods*
D004277:DNA, Single-Stranded; D017979:Gold Colloid