title: High sensitivity DNA detection using gold nanoparticle functionalised polyaniline nanofibres.
abstract: Polyaniline (PANI) nanofibres (PANI-NF) have been modified with chemically grown gold nanoparticles to give a nanocomposite material (PANI-NF-AuNP) and deposited on gold electrodes. Single stranded capture DNA was then bound to the gold nanoparticles and the underlying gold electrode and allowed to hybridise with a complementary target strand that is uniquely associated with the pathogen, Staphylococcus aureus (S. aureus), that causes mastitis. Significantly, cyclic voltammetry demonstrates that deposition of the gold nanoparticles increases the area available for DNA immobilisation by a factor of approximately 4. EPR reveals that the addition of the Au nanoparticles efficiently decreases the interactions between adjacent PANI chains and/or motional broadening. Finally, a second horseradish peroxidase (HRP) labelled DNA strand hybridises with the target allowing the concentration of the target DNA to be detected by monitoring the reduction of a hydroquinone mediator in solution. The sensors have a wide dynamic range, excellent ability to discriminate DNA mismatches and a high sensitivity. Semi-log plots of the pathogen DNA concentration vs. faradaic current were linear from 150×10(-12) to 1×10(-6) mol L(-1) and pM concentrations could be detected without the need for molecular, e.g., PCR or NASBA, amplification.
authors.affiliation: Biomedical Diagnostics Institute, School of Chemical Sciences, Dublin City University, Dublin 9, Ireland.
authors.forename: Elaine
authors.initials: E
authors.lastname: Spain
authors.forename: Robert
authors.initials: R
authors.lastname: Kojima
authors.forename: Richard B
authors.initials: RB
authors.lastname: Kaner
authors.forename: Gordan G
authors.initials: GG
authors.lastname: Wallace
authors.forename: Justin
authors.initials: J
authors.lastname: O'Grady
authors.forename: Katrina
authors.initials: K
authors.lastname: Lacey
authors.forename: Thomas
authors.initials: T
authors.lastname: Barry
authors.forename: Tia E
authors.initials: TE
authors.lastname: Keyes
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Forster
mesh_terms: D000814:Aniline Compounds / Q000737:chemistry*; D015374:Biosensing Techniques / Q000295:instrumentation*; D003217:Conductometry / Q000295:instrumentation*; D004269:DNA, Bacterial / Q000032:analysis* / Q000235:genetics; D004566:Electrodes; D004867:Equipment Design; D019544:Equipment Failure Analysis; D006046:Gold / Q000737:chemistry*; D053758:Nanoparticles / Q000737:chemistry*; D013211:Staphylococcus aureus / Q000235:genetics / Q000302:isolation & purification*
chemical_list: D000814:Aniline Compounds; D004269:DNA, Bacterial; C416807:polyaniline; D006046:Gold