Open AccessUltra-Highly Sensitive DNA Detection with Conducting Polymer-Modified Electrodes: Mechanism, Manufacture and Prospects for Rapid e-PCR
Author(s) -
Bicheng Zhu,
Thomas Kerr-Philips,
Zahraa Al Ghaus,
Edward Chan,
D. J. P. Barker,
Clive W. Evans,
David J. Williams,
Jadranka Travas-Sejdic
Publication year - 2022
Publication title -
journal of the electrochemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.258
H-Index - 271
eISSN - 1945-7111
pISSN - 0013-4651
DOI - 10.1149/1945-7111/ac5ced
Subject(s) - ferrocyanide , polymer , materials science , electrode , amplicon , conductive polymer , percolation (cognitive psychology) , oligonucleotide , polyaniline , nanotechnology , chemistry , polymerase chain reaction , dna , polymerization , gene , biochemistry , neuroscience , biology , composite material
At low copy number, sequence detection by polymerase chain reaction (PCR) requires up to 30 cycles (amplification 10 9 ) to produce a reliably detectable concentration of fluorescently-labelled amplicons. The cycle number and hence detection time is determined by the analytical sensitivity of the detector. Hybridisation of complementary DNA strands to oligonucleotide-modified conducting polymer electrodes yields an increase in the charge transfer resistance for the ferri-ferrocyanide redox couple. We demonstrate sensors using screen-printed carbon electrodes modified with a conducting polymer formed from a monomer pre-functionalised with complementary oligonucleotide, with pM sensitivity for short sequences and aM for bacterial lysate, with a response time-scale of 5 min. The response is due to the variation of electrical resistance within the polymer film. We develop a mechanism based on repulsion from the solution interface of dopant anions by the charge associated with surface-bound DNA. With results for >160 single-use sensors, we formulate a response model based on percolation within a random resistor network and highlight challenges for large-scale manufacture of such sensors. Such sensors used for label-free electrochemical detection for PCR (e-PCR) would decrease the required cycle number from 30 to less than 10 and would offer a much simplified instrument construction.