Sub-attomolar electrochemical measurement of DNA hybridization based on the detection of high coverage biobarcode latex labels at PNA-modified screen printed electrodes
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Author list: Widaningrum T., Widyastuti E., Pratiwi F.W., Faidoh Fatimah A.I., Rijiravanich P., Somasundrum M., Surareungchai W.
Publisher: Elsevier
Publication year: 2017
Journal: Talanta: The International Journal of Pure and Applied Analytical Chemistry (0039-9140)
Volume number: 167
Start page: 14
End page: 20
Number of pages: 7
ISSN: 0039-9140
eISSN: 1873-3573
Languages: English-Great Britain (EN-GB)
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Abstract
We have constructed biobarcode labels based on 468 nm diameter latex spheres. Modification with polyallylamine and then glutaraldehyde was used to attach a high DNA loading, consisting of aminated probe DNA (approx. 1.01×102 molecules per sphere) and biobarcode DNA (approx. 1.66×104 molecules per sphere). Detection of the biobarcodes was performed by application of a Ag enhancer solution, causing association of the Ag+ ions with the phosphate groups of the DNA. The deposited Ag was detected by differential pulse voltammetry. A 30 mer sequence from the BL21 strain of E. coli was detected with an LOD of 2.6 fM (calibration range 10 aM to 0.1 pM, r2=0.91, n=45). The LOD was lowered to 0.56 aM (calibration range 100 zM to 0.1 nM, r2=0.991, n=50) by utilizing a sandwich assay with PNA-modified screen printed electrodes, which lowered the Ag background current. The sandwich assay platform was used to calibrate E. coli strain BL2(DE3) with an LOD of 17.0 CFU mL−1 (calibration range 10 to 106 CFU mL−1, r2=0.99, n=33) with good discrimination against Salmonella. © 2017 Elsevier B.V.
Keywords
Electrochemical, PNA
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