Voltammetric Discrimination of DNA Single Base-Pair Mismatches via Taq DNA Ligase-Based Mismatch Recognition

An electrochemical approach for single base-specific detection of label-free target single-strand DNA (ssDNA) was demonstrated. The approach was based on the high ligation selectivity of Taq DNA ligase coupled with ferrocenated gold nanoparticle/streptavidin conjugate-based voltammetric detection method. The ferrocene (Fc) moieties of Fc-capped gold nanoparticle/streptavidin conjugates, which were selectively bound to the biotinylated DNA layer, were found to be close enough to the underlying electrode surface for facile electron transfer. The proposed electrochemical method was evaluated with label-free target DNA strands making all possible base pair combinations at the 3′-OH side of capture probe, and showed significant voltammetric signals only with a perfect match target strand.