Abstract: The primer extension(PEXT) reaction is one of the methods most commonly used in genotyping of single nucleotide polymorphisms(SNPs). Owing to the high specificity of PEXT, the extension reaction can be performed favorably only when the primer and target DNA are perfectly matched. The ferrocene can be incorporated in the extension product by primer extension reaction, which is then captured by the capture probe self-assembled on the electrode surface. Differential pulse voltammetry(DPV) was used to detect the presence of the ferrocene in close proximity of the gold electrode surface. The effects of the annealing temperature, concentration of polymerse and the hybridization temperature on the peak current were evaluated in detail. Furthermore, this proposed method was successfully applied to the genotyping of SNPs at β-Thalassemia(CD28). The detection limit of this method can be reached down to 0.86 fmol/L and the experimental results show that it is a simple, speedy and sensitive approach for genotyping of SNPs.

Key words: Primer extension reaction, Single nucleotide polymorphisms, Genotyping, Ferrocene