Label Free Colorimetric Detection of Single Nucleotide Polymorphisms in Pcr Amplified Genomic DNA

Keywords:
PCR, DNA, gold nanoparticle, colorimetric detection, Au nanoparticles

Abstract:
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