Are we prepared for the revolution in diagnostic technology?

The advances in diagnostic technology have been significant over the past 3 decades. The introduction of the enzyme linked immunoabsorbent assay (ELISA) revolutionised serological assays and enabled large scale automation of serological testing. Equally, the introduction of the polymerase chain reaction (PCR) enabled the amplification of DNA and RNA gene segments and the detection of infectious agents with high sensitivity and specificity.

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The differences in sensitivity and specificity between three different kits for the detection Rotavirus

The Iraqi Journal of Veterinary Medicine ◽

10.30539/iraqijvm.v41i2.67 ◽

2018 ◽

Vol 41 (2) ◽

pp. 168-173

Author(s):

Modher Nagem Abed

Keyword(s):

Polymerase Chain Reaction ◽

Large Scale ◽

Quantitative Estimation ◽

High Sensitivity ◽

Conventional Polymerase Chain Reaction ◽

Patient Treatment ◽

Enzyme Linked Immunosorbent Assay ◽

Chain Reaction ◽

Stool Specimens ◽

Polymerase Chain

Rotavirus is the common key etiologic agents of attained diarrhea in infant, young children and neonatal calves globally. It is very important to early diagnose the disease in purpose of effective patient treatment. This study was conducted by using three different kits for detecting Rotavirus in calves in five Iraqi governorates (Al-qadissiya, Babel, Kerbala, Missan, Wassit). A total of 125 stool specimens were examined, they were collected from calves in the (period from November 2015 to February 2016). The ages ranged from 1 to 16 weeks. Stool samples were collected and examined using Chromatographic Immunoassay, enzyme-linked immunosorbent assay and Polymerase-chain reaction. The results obtained by chromatographic immunoassay were 44% positive, ELISA 42% positive, and 38% Polymerase-chain reaction positive. Chromatographic immunoassay was easy, simple, economic, and rapid and showed high sensitivity with accepted specificity while ELISA permit quantitative estimation of Rotavirus antigens. These results indicate that ELISA is as sensitive and specific assay as the chromatographic immunoassay, and it could be applied on a large scale for screening stool specimens in suspected rotavirus diarrhea. Conventional Polymerase-chain reaction demonstrated more sensitivity and highest specificity.

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Ultra-high sensitivity measurement of DNA sequences with conducting polymer-modified electrodes: mechanism, large-scale manufacture, and prospects for rapid polymerase chain reaction measurement (e-PCR)

10.33774/chemrxiv-2021-hnpk3 ◽

2021 ◽

Author(s):

Bicheng Zhu ◽

Thomas Kerr-Philips ◽

Zahraa Al-Ghaus ◽

Eddie Chan ◽

David Barker ◽

...

Keyword(s):

Polymerase Chain Reaction ◽

Conducting Polymer ◽

Large Scale ◽

High Sensitivity ◽

Redox Couple ◽

Analytical Sensitivity ◽

Chain Reaction ◽

Cycle Number ◽

Polymerase Chain ◽

Large Scale Manufacture

At low copy number, sequence detection by polymerase chain reaction (PCR) requires up to 30 cycles (amplification by a factor of 109) 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. Sensors using this technology for e-PCR offer a label-free method with detector sensitivity in the pM range, potentially decreasing the required cycle number from 30 to 10 and offering a much simplified instrument construction. We demonstrate sensors using screen-printed carbon electrodes modified with a conducting polymer formed from a monomer pre-functionalised with complementary oligonucleotide. Off-chip pre-functionalisation of the conducting polymer precursor is a key step towards practical manufacture and the method is potentially a general one for sensors which require a capture probe-functionalised surface. We demonstrate reliable sensitivity of the interfacial resistance change at the pM scale for short (20-mer) sequences and at the aM scale for bacterial lysate, with dynamic range extending to μM scale and response time-scale 5 min. Donnan exclusion of the redox couple from the surface, as previously proposed, seems unlikely as a mechanism for such ultra-high sensitivity. We demonstrate that the most important element in the response at the lowest concentrations is due to variation of an electrical resistance within the polymer film. We develop a mechanism based on repulsion from the solution interface of dopant anions and attraction towards and trapping at the interface of radical cations (polarons) 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. We propose a PCR device concept for rapid use at point-of-sampling.

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