The single nucleotide polymorphism (SNP) of the vangl1 gene is highly correlated with Neural Tube Defects (NTDs), a group of severe congenital malformations. It is hindered by the lack of a quantitative detection method. We first propose the use of a DNA biosensor to detect the missense single nucleotide polymorphism (rs4839469 c.346G>A p.Ala116Thr) of the vangl1 gene in this work. Polypyrrole (PPy) and streptavidin were integrated to modify a gold electrode. We took advantage of the PPy's good biocompatibility and excellent conductivity. To further accelerate the electron transfer process at the electrode surface, polyamidoamine dendrimer-encapsulated gold nanoparticles (Au-PAMAM) were used, because Au-PAMAM possess a large number of amino groups to load capture probes (CP). Using the biotin-streptavidin system, the Au-PAMAM-CP bionanocomposite probe, which can detect the target DNA, was conjugated to the electrode surface. Under optimal conditions, the DNA biosensor exhibited a wide linear range of 0.1-100 nM with a low detection limit of 0.033 nM (S/N=3). The results suggest that this approach has the potential to be used in clinical research.
Keywords: Au-PAMAM; Capture probe; DNA biosensor; PPy/ streptavidin.
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