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The aim of this study was to develop a highly specific electrochemical DNA sensor using functionalized lead sulphide (PbS) quantum dots for hepatitis E virus genotype 3 (HEV3) DNA target detection. Functionalized-PbS quantum dots (QDs) were used as an electrochemical label for the detection of HEV3-DNA target by the technique of square wave anodic stripping voltammetry (SWASV). The functionalized-PbS quantum dots were characterized by UV-vis, FTIR, XRD, TEM and zeta potential techniques. As-prepared, functionalized-PbS quantum dots have an average size of 4.15 ± 1.35 nm. The detection platform exhibited LOD and LOQ values of 1.23 fM and 2.11 fM, respectively. HEV3-DNA target spiked serum is also reported.Graphical abstract.

DNA strand displacement is an attractive, enzyme-free target hybridization strategy for nano-biosensing. The target DNA induces a strand displacement reaction by replacing the pre-hybridized strand that is labeled with gold nanoparticles (AuNPs). Thus, the amount of displaced-AuNP-labeled strand is proportional to the amount of target DNA in the sample. The use of a magnetogenosensing technique to isolate the target DNA allows for a simple, one-pot detection approach, which minimizes possible carry-over contamination and pipetting errors. We sought a proof-of-concept for this technology in its ability to detect DNA-equivalent of hepatitis E virus (HEV), which causes acute viral hepatitis for which rapid and simple diagnostic methods remain limited. Signal detection was done via visual observation, spectrophotometry, and electrochemistry. The sensor demonstrated good sensitivity with detection limits of 10 pM (visual), 10 pM (spectrophotometry) and 1 fM (electrochemical). This sensor also exhibited high specificity for real target amplicons and could discriminate between perfect and mismatched sequences. Lyophilized biosensor reagents stored at 4 °C, 25 °C, and outdoor ambient temperature, were stable for up to 90, 50, and 40 days, respectively. The integration of magnetic separation and target DNA-induced strand displacement reaction in a dry reagent form makes the sensing platform easy-to-use and suitable for field settings., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2020 Elsevier B.V. All rights reserved.)