Ultrasensitive chemiluminescence quantification of single-nucleotide polymorphisms by using monobase-modified Au and CuS nanoparticles

An ultrasensitive chemiluminescence method based on the Au nanoparticles amplification for the quantitative detection of single-nucleotide polymorphisms (SNPs) in genomic DNA was accomplished by the DNA polymerase I (Klenow fragment)-induced coupling of the nucleotide-modified nanoparticle probe to the mutant sites of duplex DNA under the Watson-Crick base-pairing rule. The concentration of the one-base mutant DNA was determined by chemiluminescence (CL) detection of the cupric ions dissolved from the CuS nanoparticles (NPs) modified on the Au NPs. The incorporation of Au NPs in this method significantly enhanced the sensitivity because a single Au NP can be loaded with 77 CuS NPs through the link-age of an amidization reaction between mercaptoacetic acid on the surface of Au NPs and aminoethanethiol on the surface of CuS NPs. A preconcentration process of cupric ions performed by anodic stripping voltammetric (ASV) technology further increased the sensitivity of the design for about 10-fold. As a result of these two combined effects, this method could detect as low as 19 aM SNPs and the linear range for SNPs was from 8.0 × 10^-17 to 1.0 × 10^-14 M.