Detection of single nucleotide polymorphisms (SNPs) is critical for early stage diagnosis. However, available clinical methods
for detecting SNPs require strict assay conditions or complicated enzyme reactions. DNA hybridization by Au nanoparticles is a new microscopic
method for DNA detection, which offers many advantages over traditional ones. But currently, this method is limitedly used
because of low yield of hybridization. Here we report novel strategies which use toehold-mediated strand displacement on DNA origami
Chip by employing AuNPs, and we greatly improved the yield of hybridization to 80% from less than 10%. Based on the kinetic characteristic
of toehold-mediated strand displacement reaction, DNA strands with unmatched sequences can be easily replaced by fully complementary
ones, and the exchange rate depends on the length of the toehold region. Therefore, variation on ssDNA sequence can be differentiated
by their different displacement time. With this approach we detect SNPs of age-related macular degeneration on DNA origami
chip. This approach offers a new, simple and sensitive way to detect SNP.
Keywords: Age-related macular degeneration (AMD), atomic force microscope (AFM), Au nanoparticle (AuNP), DNA origami chips, single-
nucleotide polymorphisms (SNPs).
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