Thionin attached to a gold electrode modified with self-assembly of Mo(6)S(9-X)I(X) nanowires for amplified electrochemical detection of natural DNA.

We demonstrate a novel electrochemical sensor for highly sensitive detection of natural double-stranded deoxyribonucleic acid (dsDNA) based on thionin (Th) attached to Mo(6)S(9-X)I(X) nanowires (MoSI NWs) self-assembled on a gold electrode. The sensing detection is based on a decrease of the voltammetric response of the immobilized Th due to the binding of Th with dsDNA through intercalation. MoSI NWs act as molecular connectors to provide an amplification and conductive sensing platform for the electrochemical detection of dsDNA, because many sulfur atoms at the ends and sides of MoSI NWs permit covalent bonds to be formed with gold as well as MoSI NWs with negative charges allow electrostatic binding with Th. A determination limit of 0.62 ng/mL for dsDNA with this novel sensor is achieved, which is three orders of magnitude lower than that in the absence of MoSI NWs. The operation is simple and label-free.