AN ELECTROCHEMICAL BIOSENSOR FOR THE DETERMINATION OF GANODERMA BONINENSE PATHOGEN BASED ON A NOVEL MODIFIED GOLD NANOCOMPOSITE FILM ELECTRODE

A sensitive approach for the determination of Ganoderma boninense DNA is reported based on an electrochemical affinity system using a modified gold sensor. Covalent attachment of probe DNA was achieved by attachment of the amine group to a carboxylic acid group of a 3,3'-dithiodipropionic acid monolayer on a nanocomposite film of gold nanoparticles bound to poly(3,4-ethylenedioxythiophen)-poly(styrenesulfonate) on a gold working electrode. The electrochemical detection of sequence-specific DNA of probe and target DNA hybridization was monitored using a new ruthenium complex [Ru(dppz) (2) (qtpy)Cl (2) ; dppz=dipyrido [3,2-a:2',3'-c] phenazine; qtpy=2,2',-4,4.4'4'-quarterpyridyl redox marker. The potential was selected through the study of the electrochemical behavior of trisaminomethane-hydrochloride containing a ethylenediaminetetraacetic acid supporting electrolyte on the bare and modified gold electrode. The effect of the hybridization temperature and time were measured. The sensor demonstrated specific detection for the target over a concentration range of 1.0x10(-15) M to 1.0x10(-9) M with a detection limit of 1.59x10(-17) M. Control experiments verified the specificity of the biosensor in the presence of a single mismatched DNA sequence. This detection technology was shown to be effective in terms of sensitivity and selectivity of hybridization events and is a promising device for early detection of Ganoderma boninense and other pathogenic threat agents.