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Infectious diseases in goats, CAE in particular have widely affected the productivity of this animal and greatly affected the farmers and the small ruminant industry. Molecular technique such as LAMP has been applied to detect the CAEV proviral DNA specifically and sensitively but this technique has its own drawback. Gold is the most widely used nanoparticle (NP) which has excellent properties such as high surface area and compatibility with biomolecules. In this study, gold nanoparticle (AuNP) conjugated with modified oligonucleotides or gold nanoprobe (AuPr) was used to detect CAEV proviral DNA in LAMP product. The hybridization of AuPr to a complementary sequence on the LAMP product made the gold resistant to high salt concentration. This resistance or non-resistance of the AuNP is observed as color change in the mixture. This study, reported a simple method of visual detection of CAEV proviral DNA in LAMP product using AuPr. [ABSTRACT FROM AUTHOR]

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. An electrochemical DNA sensor for the hepatitis E virus (HEV) which infects animals, transmits into food and contaminates water. Image 1 • One-pot detection with femtomolar limit of detection. • Signal interpretation can be achieved in three ways, visual observation, spectrophotometry, and electrochemical detection. • The integration of lyophilization and magnetogenosensing makes the test stable and easy to transport. • This platform can potentially detect nucleic acid of any viral or bacterial pathogen in infected samples. [ABSTRACT FROM AUTHOR]

The ability of a diagnostic test to detect multiple pathogens simultaneously is useful to obtain meaningful information for clinical treatment and preventive measures. We report a highly sensitive and specific electrochemical biosensor assay for simultaneous detection of three gene targets using quantum dots (QDs). The targets are novel non-protein coding RNA (npcRNA) sequences of Vibrio cholerae , Salmonella sp. and Shigella sp., which cause diarrheal diseases. QDs (PbS, CdS, ZnS) were synthesized and functionalized with DNA probes that were specific to each pathogen. Electrochemical detection of QDs was performed using square wave anodic stripping voltammetry (SWASV). The QDs gave distinct peaks at 0.5 V (PbS), 0.75 V (CdS) and 1.1 V (ZnS). There was no interference in signal response when all three QDs were mixed and detected simultaneously. The detection limits of single and multiplex assays with linear targets and PCR products were in the attomolar ranges. The high assay sensitivity, in combination with specific npcRNA sequences as novel diagnostic targets, makes it a viable tool for detecting pathogens from food, environment and clinical samples. [ABSTRACT FROM AUTHOR]