Label Free Colorimetric Detection of Single Nucleotide Polymorphisms in Pcr Amplified Genomic DNA
H.X. Li and L.J. Rothberg
University of Rochester, US
PCR, DNA, gold nanoparticle, colorimetric detection, Au nanoparticles
Analysis of DNA is increasingly important in clinical diagnosis, pathology and genetics1, 2. Single nucleotide polymorphisms (SNPs) in genomic DNA are known to be responsible for a number of hereditary conditions3 and cancers4. Nearly all assays for DNA are based on the polymerase chain reaction (PCR), a rapid, inexpensive and simple means of amplifying specific sequence segments from as little as a single copy of DNA to easily detected quantities5, 6. Post processing of PCR amplified samples can, however, be expensive and time-consuming7. Here we demonstarte a label free colorimetric assay for SNPs in PCR amplified genomic DNA within ten minutes without need of time-consuming labeling, surface functionalization processes and additional detection instrumentation8. This assay is based on our new observation that single stranded DNA (ss-DNA) adsorbs on gold nanoparticles (Au-np) with a rate that depends on sequence length and temperature, and the adsorption can prevent the Au-np against salt-induced aggregation.
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Nanotech 2005 Conference Program Abstract