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The University of Southampton

Eva Papadopoulou

Eva Papadopoulou (20 mins talk + 10 mins questions)

School of Chemistry, University of Southampton

Title: Electrochemical melting monitored by surface enhanced Raman spectroscopy is used for the discrimination of mutations and short tandem repeats.

Abstract: Discrimination of single nucleotide polymorphism and short tandem repeats from unpurified PCR amplicons extracted from Yersinia pestis pathogenic bacteria is achieved utilising SERS and electrochemical melting. A differential denaturation method is used that allow us to identify sequences with difference in structural stability. Sphere segment void (SSV) surfaces are the SERS active substrates that are made by metal electrodeposition of templates around a hexagonally close packed array of uniform polystyrene spheres. These surfaces are excellent SERS substrates and can also be used as electrodes. A DNA probe is bound on an SSV surface via a series of three di-thiol linkers followed by hybridisation with the DNA target that is labelled with a Raman active dye. Denaturation of the DNA duplexes is achieved electrochemically by applying negative potentials. SERS spectra are recorded as the potential is scanned to melt the DNA from which an electrochemical melting curve can be constructed. The effect of the experimental temperature and DNA orientation on the metal surface was studied in detail. By conducting the experiment at lower temperature the melting curves become steeper and the melting potentials drop. By immobilising the DNA horizontally on the surface, ds-binding agents can be used to monitor the DNA melting allowing label free DNA analysis.

Biography: Evanthia obtained her PhD from Queen’s University Belfast in physical chemistry in 2011. Her thesis was entitled “Detection of DNA components and DNA sequences by surface enhanced Raman spectroscopy (SERS)”. Following her PhD, she continued in Belfast for a short post doc, during which she worked on the sub-picomole detection of diagnostic markers for airway infections using SERS. Evanthia joined the chemistry department of the University of Southampton in 2012 to work on a joint project between Prof. Phil Bartlett and Prof. Tom Brown’s research groups, funded by Defence Science and Technology Laboratory (DSTL). The project is on DNA detection and discrimination using SERS via measurement of electrochemically driven dsDNA denaturation.

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