Conductive architecture of Fe2O3 microspheres/self-doped polyaniline nanofibers on carbon ionic liquid electrode for impedance sensing of DNA hybridization
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Abstract
A novel architecture was designed by combining the strong adsorption ability of Fe(2)O(3)
microspheres to the DNA probes and excellent conductivity of self-doped polyaniline
(SPAN) nanofibers (copolymer of aniline and m-aminobenzenesulfonic acid) on carbon
ionic liquid electrode (CILE) for electrochemical impedance sensing of the immobilization
and hybridization of DNA. The formed conductive Fe(2)O(3)/SPAN membrane on the CILE
was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy
(EIS) using [Fe(CN)(6)](3-/4-) as the indicator. The immobilization of the probe DNA
on the surface of electrode and the sensitivity of DNA hybridization recognition were
dramatically enhanced due to the unique synergistic effect of Fe(2)O(3) microspheres,
SPAN nanofibers and ionic liquid. The DNA hybridization events were monitored with
a label-free EIS strategy. Under optimal conditions, the dynamic range of this DNA
biosensor for detecting the sequence-specific DNA of phosphoenolpyruvate carboxylase
(PEPCase) gene from transgenically modified rape was from 1.0 x 10(-13) to 1.0 x 10(-7)mol/L,
and the detection limit was 2.1 x 10(-14)mol/L. This work suggested a simple strategy
to prepare a conductive interface for electrochemical detection of DNA hybridization
and opened a way for the application of Fe(2)O(3) in DNA electrochemical biosensing.