Arotiba, Omotayo A.Owino, JosephSonga, EverlyneHendricks, NicoletteWaryo, Tesfaye T.Jahed, NazeemBaker, PriscillaIwuoha, Emmanuel I.2016-12-212016-12-212008Omotayo, A. et al. (2008). An electrochemical DNA biosensor developed on a nanocomposite platform of gold and poly(propyleneimine) dendrimer. Sensors, 8: 6791-68091424-8220http://hdl.handle.net/10566/2474http://dx.doi.org/10.3390/s8128262An electrochemical DNA nanobiosensor was prepared by immobilization of a 20mer thiolated probe DNA on electro-deposited generation 4 (G4) poly(propyleneimine) dendrimer (PPI) doped with gold nanoparticles (AuNP) as platform, on a glassy carbon electrode (GCE). Field emission scanning electron microscopy results confirmed the codeposition of PPI (which was linked to the carbon electrode surface by C-N covalent bonds) and AuNP ca 60 nm. Voltammetric interrogations showed that the platform (GCE/PPI-AuNP) was conducting and exhibited reversible electrochemistry (E°′ = 235 mV) in pH 7.2 phosphate buffer saline solution (PBS) due to the PPI component. The redox chemistry of PPI was pH dependent and involves a two electron, one proton process, as interpreted from a 28 mV/pH value obtained from pH studies. The charge transfer resistance (Rct) from the electrochemical impedance spectroscopy (EIS) profiles of GCE/PPI-AuNP monitored with ferro/ferricyanide (Fe(CN)6 3-/4-) redox probe, decreased by 81% compared to bare GCE. The conductivity (in PBS) and reduced Rct (in Fe(CN)6 3-/4-) values confirmed PPI-AuNP as a suitable electron transfer mediator platform for voltammetric and impedimetric DNA biosensor. The DNA probe was effectively wired onto the GCE/PPI-AuNP via Au-S linkage and electrostatic interactions. The nanobiosensor responses to target DNA which gave a dynamic linear range of 0.01 - 5 nM in PBS was based on the changes in Rct values using Fe(CN)6 3-/4- redox probe.enAll articles published by MDPI are made immediately available worldwide under an open access license.Poly(propyleneimine) dendrimerGold nanoparticleElectrochemical impedance spectroscopyElectrochemical DNA biosensorDNAArticle