Highly sensitive electrochemical detection of genomic DNA based on stem loop probes structured for magnetic collection and measurement via metalised hollow polyelectrolyte shells

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Author list: Khunrattanaporn N., Rijiravanich P., Somasundrum M., Surareungchai W.

Publisher: Elsevier

Publication year: 2015

Journal: Biosensors and Bioelectronics (0956-5663)

Volume number: 73

Start page: 181

End page: 187

Number of pages: 7

ISSN: 0956-5663

URL: https://www.scopus.com/inward/record.uri?eid=2-s2.0-84934919542&doi=10.1016%2fj.bios.2015.05.068&partnerID=40&md5=4d393d71b617c98bf51f829d5fc11afb

Languages: English-Great Britain (EN-GB)

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Abstract

We report a highly sensitive method for the electrochemical detection of genomic DNA, based on the employment of two sub-micron oligonucleotide labels - one for magnetic collection and the other for voltammetric detection - and their incorporation onto a stem loop DNA probe. The magnetic label consists of a latex particle of mean diameter 441ฑ6nm, bearing magnetic Fe3O4 particles and approx. 3.5ื105 anti-DIG antibodies. The voltammetric label is a hollow polyelectrolyte shell containing approx. 1.0ื1011 Au atoms in the form of well dispersed Au nanoparticles. A DIG tag on one arm of the stem loop enables binding to the magnetic label, while a thiol tag on the other arm enables attachment to the Au nanoparticles. Due to steric hindrance from the two relatively large labels, attachment of both moieties is dependant on target-probe hybridisation straightening the loop. Once attached, sensitive DNA measurement is facilitated by magnetic collection of the DNA into a small volume and by the high quantity of Au atoms available for detection. Using differential pulse anodic stripping voltammetry we calibrated a 30mer sequence common to 71 strains of Escherichia coli across the concentration range from 0.1aM to 100pM with a LOD of 1.8aM. Three strains of E. coli, BL 21, ATCC8739, O157:H7, when spiked into UHT milk and fermented palm juice, could be detected with LODs of approx. 2-4CFUmL-1 in an assay time of approx. 140min. ฉ 2015 Elsevier B.V.

Keywords

DNA biosensor