Atomic-level detection of mercury based on DNA hybridization-dehybridization of doublestrand DNA (dsDNA) modified gold electrode is presented. A single strand DNA (ssDNA) treated by thiol-substitute is self-assembled on a gold electrode surface supplemented by S-Au bond. The hybridization of ssDNA and complementary DNA (cDNA) followed by dehybridization in the presence of mercury ions is recorded by differential pulse voltammetry (DPV) technique using Fe(CN)6 3- as redox probe. The sensor is highly selective to Hg+2, without interference from other metals ions. Current sensitive electrochemical aptasensor is able to specifically detect a countable number of Hg+2 ions at range of 5 zeptomolar to 55 picomolar with limit of detection of 6×10-22 M close to the dream of single atomic detection without utilizing any complicated procedure and materials. Compared with previous reports, the proposed method manifested .Great advantages including high sensitivity, rapid response, stability, low cost and ease of operation.
