title: Electrochemical coding of single-nucleotide polymorphisms by monobase-modified gold nanoparticles.
abstract: Rapidly increasing information about the human genome requires a fast and simple method for the detection of single-nucleotide polymorphisms (SNPs). To date, the conventional SNP detection technologies have been unable to identify all possible SNPs and needed further development in cost, speed, and sensitivity. Here we describe a novel method to discriminate and code all possible combinations. SNPs were coded by monitoring the changes in the electrochemical signal of the monobase-modified colloidal gold (Au) nanoparticles. First, a chitosan layer was formed on the alkanethiol self-assembled monolayer-modified Au nanoparticle. The monobases were then attached onto the chitosan-coated Au nanoparticles through their 5' phosphate group via the formation of a phosphoramidate bond with the free amino groups of chitosan. The size of the surface-modified Au nanoparticle was found to be 8.46 +/- 1.53 nm by using atomic force microscopy. If there is a SNP in DNA and the mismatched bases are complementary to the monobase, Au nanoparticles accumulate on the electrode surface in the presence of DNA polymerase I (Klenow fragment), thus resulting in a significant change in the Au oxide wave. In this report, monobase-modified Au nanoparticles show not only the presence of a SNP, but also identify which bases are involved within the pair. Especially, the identification of a transversion SNP, which contains a couple of the same pyrimidine or purine bases, is greatly simplified. A model study was performed by using a synthetic 21-base DNA probe related to tumor necrosis factor (TNF-alpha) along with its all possible mutant combinations. This versatile nanoparticle-based electrochemical protocol is a promising candidate for coding all mutational changes.
authors.affiliation: School of Materials Science, Japan Advanced Institute of Science and Technology, 1-1 Asahidai, Tatsunokuchi, Ishikawa 923-1292, Japan.
authors.forename: Kagan
authors.initials: K
authors.lastname: Kerman
authors.forename: Masato
authors.initials: M
authors.lastname: Saito
authors.forename: Yasutaka
authors.initials: Y
authors.lastname: Morita
authors.forename: Yuzuru
authors.initials: Y
authors.lastname: Takamura
authors.forename: Mehmet
authors.initials: M
authors.lastname: Ozsoz
authors.forename: Eiichi
authors.initials: E
authors.lastname: Tamiya
mesh_terms: D001483:Base Sequence; D004563:Electrochemistry / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D018625:Microscopy, Atomic Force; D008969:Molecular Sequence Data; D049329:Nanostructures; D036103:Nanotechnology; D009693:Nucleic Acid Hybridization; D020641:Polymorphism, Single Nucleotide; D017422:Sequence Analysis, DNA / Q000379:methods*; D014409:Tumor Necrosis Factor-alpha / Q000737:chemistry / Q000235:genetics
chemical_list: D014409:Tumor Necrosis Factor-alpha; D006046:Gold