One-pot synthesis of fluorescent oligonucleotide Ag nanoclusters for specific and sensitive detection of DNA

In this study, we prepared fluorescent, functional oligonucleotide-stabilized silver nanoclusters (FFDNA-Ag NCs) through one-pot synthesis and then employed them as probes for single nucleotide polymorphisms (SNPs). The FFDNA-Ag NCs were obtained through the NaBH₄-mediated reduction of AgNO₃ in the presence of a DNA strand having the sequence 5'-C₁₂-CCAGATACTCACCGG-3'. The specific DNA scaffold combines a fluorescent base motif (C₁₂) and a specific sequence (CCAGATACTCACCGG) that recognizes a gene for fumarylacetoacetate hydrolase (FAH). The sensing mechanism of our new probe is based on the FFDNA-Ag NCs having different stabilities (fluorescence intensities) in solutions containing 150mM NaCl in the absence and presence of perfect match DNA (DNA_pmt). Under the optimal conditions (150mM NaCl, 20mM phosphate solution, pH 7.0), the fluorescence ratios of the FFDNA-Ag NC probes in the presence and absence of DNA_pmt, plotted against the concentration of DNA_pmt, was linear over the range 25-1000nM (R²=0.98), with a limit of detection (S/N=3) of 14nM. This cost-effective and simple FFDNA-Ag NC probe is sensitive and selective for SNPs of a gene for FAH.