Intrinsic Electrocatalysis in DNA

Abstrakt

We show, for the first time, that DNA produces an electrocatalytic square wave voltammetric reduction peak or chronopotentiometric peak H-DNA at mercury and solid amalgam electrodes. These peaks are attributed to the catalytic hydrogen evolution reaction, allowing label-free detection of chromosomal DNA and oligodeoxynucleotides (ODNs) below parts per million and nanomolar levels, respectively. By using peak H-DNA at high current densities, native chromosomal DNA was distinguished from its denatured form. With this method, damage of DNA from human cancer cells by ionizing radiation or sonication was detected. Sensitivity of the DNA determination was greatly enhanced in the presence of {[}Co(NH3)(6)](3+). Chromosomal DNA and ODNs can be detected at concentrations 2-3 orders lower than any earlier voltammetric or chronopotentiometric label-free methods. In the presence of 4 mM {[}Co(NH3)(6)](3+), DNA from human cancer cells was easily detected at 5ng/mL, that is, below the concentration level of cell-free DNA in body fluids.