Electrochemical Biosensor for Detection of Target DNA Sequence and Single-Base Mismatch Related to Helicobacter Pylori Using Chlorogenic Acid as Hybridization Indicator

Abstract

An electrochemical DNA hybridization biosensor was developed using a novel electroactive indicator. The DNA hybridization was detected based on the interaction of chlorogenic acid, CGA, with an 18-mer alkanethiol DNA probe (from Helicobacter pylori) self-assembled gold electrode (S1/MCH/AuE) and its hybridization form (S2-S1/MCH/AuE). The conditions were optimized for the immobilization of probe DNA, the exposure of MCH, the accumulation of indicator and the hybridization process. The differential pulse voltammetric response of the accumulated CGA, as an electroactive indicator, on different electrode surfaces was used to assess the DNA hybridization. The results indicate that there is a significant difference between the voltammetric responses of CGA accumulated on the probes hybridized with non-complementary, mismatch and complementary targets. The potential of the developed biosensor is, thus, confirmed in detecting and discriminating the target complementary DNA from non-complementary and mismatch oligonucleotides. In optimum conditions, CGA electrochemical signals had a linear dependence on the concentration of the complementary DNA within the range of 20.0 to 410.0 nM. Finally, a detection limit of 7.2 nM was obtained for the target DNA.