S.W. Dutse, N.A. Yusof, H. Ahmad
Hussaini Adamu Federal Polytechnic, Nigeria
pp. 128 - 132
Keywords: biosensor, Pedot-Pss, DNA, Nanocomposite, ruthenium complex
The sensitivity of a designed electrochemical DNA biosensor was improved using gold and or silver nanoparticles. A gold electrode modified with a conductive nanocomposite of poly(3,4-ethylenedioxythiophen)–poly(styrenesulfonate) (Pedot-Pss) and gold or silver nanoparticles enhanced the conductivity of the electrode surface area. Bare and modified gold electrode surfaces were characterized using cyclic voltammetry (CV) technique in ethylenediaminetetraacetic acid (TE) supporting electrolyte. Immobilization of a 20-mer single stranded deoxyribonucleic acid (ssDNA) probe as the bioreceptor of the sensor was achieved by covalent attachment of the amine group of the capture probe. After denaturation of the target DNA, hybridization of the bioreceptor and the target DNA was monitored using a new ruthenium complex [Ru (dppz)2(qtpy)Cl2; dppz=dipyrido [3,2–a:2’,3’-c] phenazine; qtpy=2,2’,-4,4”.4’4”’-quarterpyridyl redox indicator intercalated into the DNA double helix. The potential was selected through the study of electrochemical behavior of Potassium Hexacyanoferrate III (K3Fe(CN)6) containing a ethylenediaminetetraacetic acid (TE) supporting electrolyte. The effect of hybridization temperature and time was optimized and the sensor demonstrated specific detection for the target concentration ranged between 1.0×10−15M to 1.0×10−9M with a detection limit of 9.70 ×10−19 M. Control experiments verified the specificity of the biosensor in the presence of a single-mismatched DNA sequence.