Browsing by Author "Lawrenson, Nicholas"
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- ItemDesign of an electrochemically reactive HIV DNA biosensor by use of hairpin DNA Probes on carbon nanofibers.(Stellenbosch : Stellenbosch University, 2018-03) Lawrenson, Nicholas; Perold, Willem; Van Zyl, G.; Stellenbosch University. Faculty of Engineering. Dept. of Electrical and Electronic Engineering.ENGLISH ABSTRACT: A low cost, electrochemical HIV DNA biosensor was investigated using hairpin DNA probes immobilized on carbon nanofibers. The basic biosensor model, as well as electrochemical and optical based biosensor techniques, were explored. The electrochemical and optical techniques were evaluated for use in low-cost HIV DNA detection. A resistive based electrochemical technique was chosen to detect the presence of HIV single stranded DNA. A carbon nanofiber mat was used as the selected transducer, with hairpin probe DNA immobilized by self assembled monolayers. The self assembled monolayers were formed by gold-thiol bonding where gold was sputter coated onto the carbon nanofibers. The immobilization of the hairpin probe was validated by use of a fluorescent label and confocal microscopy. A high precision and low current sensing circuit was designed to detect the change in resistance of the transducer during a hybridization event. A user friendly graphic user interface was designed to conduct, display and record all data during testing. A ferrocene labelled hairpin probe was used for all electronic based testing. It is believed that a ferrocene modification will increase electrochemical reactions in biosensors. It was found that the designed hairpins operated as expected during fluorescent based testing, but it was not possible to obtain an electronic signal. Various post processing methods were explored to increase the chance of detection of HIV DNA and it was found that the sensor was able to detect the addition of a sample solution, but not necessarily HIV DNA. Various optimizations and alternative solutions were suggested and it is believed that, with some minor changes, a resistive based biosensor to detect HIV DNA is very possible.