title: The effect of the oxidation state of a terthiophene-conducting polymer and of the presence of a redox probe on its gene-sensing properties.
abstract: The gene-sensing properties of sensor films made of a terthiophene-conducting polymer, poly(3-((2':2'', 5'':2'''-terthiophene)-3''-yl)acrylic acid) (PTAA), were evaluated using electrochemical impedance spectroscopy for films in their reduced and oxidised states with and without the Fe(CN)(6)(3-/4-) redox probe (RP) in dilute tris-EDTA buffer. Porous films of PTAA were prepared and attached to an oligonucleotide sequence specific to the Salmonella virulence gene InvA. These films could be described with a dual transmission line model in which the polymer conductivity was increased as a consequence of surface binding of complementary DNA. The effect is analogous to that reported for silicon nanowires and field-effect transistors in dilute electrolyte modified by charge exchange across the polymer-electrolyte interface. As a result, gene sensing could be conveniently observed as a change in the impedance phase angle at a fixed frequency.
authors.affiliation: Polymer Electronics Research Centre (PERC), The University of Auckland, Private Bag 92019, Auckland 1010, New Zealand.
authors.forename: John B
authors.initials: JB
authors.lastname: Spires
authors.forename: Hui
authors.initials: H
authors.lastname: Peng
authors.forename: David E
authors.initials: DE
authors.lastname: Williams
authors.forename: Bryon E
authors.initials: BE
authors.lastname: Wright
authors.forename: Christian
authors.initials: C
authors.lastname: Soeller
authors.forename: Jadranka
authors.initials: J
authors.lastname: Travas-Sejdic
mesh_terms: D001426:Bacterial Proteins / Q000032:analysis* / Q000235:genetics*; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods; D004269:DNA, Bacterial / Q000032:analysis* / Q000235:genetics*; D004553:Electric Conductivity; D004563:Electrochemistry / Q000295:instrumentation*; D004867:Equipment Design; D019544:Equipment Failure Analysis; D020869:Gene Expression Profiling / Q000295:instrumentation* / Q000379:methods; D010084:Oxidation-Reduction; D011108:Polymers / Q000737:chemistry; D015203:Reproducibility of Results; D012475:Salmonella / Q000235:genetics*; D012680:Sensitivity and Specificity; D013876:Thiophenes / Q000737:chemistry*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D011108:Polymers; D013876:Thiophenes; C019101:alpha-terthienyl; C075518:invA protein, Bacteria