The development of a hand-held, self-powering bio-sensing device for the early detection of mycobacterium tuberculosis

Tom, Sihle Christopher (2019-04)

Thesis (MEng)--Stellenbosch University, 2019.

Thesis

ENGLISH ABSTRACT: Tuberculosis (TB) has been described as one of the top 10 leading infectious and deadliest diseases in the world and millions of people still contract and die from TB each year. TB diagnosis serves as one of the most important aspects towards controlling and ending TB. The current methods of testing for TB infection are very expensive and non-portable, laboratory-based, require experienced personnel, sometimes with poor accuracy and lack the ability to generate same-day results at point-of-care. Hence, the time from diagnosis to treatment is unnecessarily prolonged. This project presents the fabrication of a low-cost, portable, electronic biosensor for the early detection of Tuberculosis. A biotin-modified probe was linked using the non-covalent interaction of streptavidin-biotin and immobilised on Zinc Oxide (ZnO) nanosensor. Streptavidin and biotin immobilisation was studied and confirmed using a Fourier Transform Infrared (FTIR). The ZnO nanowires were grown and optimized using the electrochemical deposition technique, which helped to improve the c-axis alignment of the nanowires. The ZnO nanowires were characterized using a scanning electron microscopy (SEM). Probe immobilisation was studied and confirmed using an atomic force microscopy (AFM) and the piezoelectric response of the nanosensor itself. The high affinity of the biotinylated-probe, immobilised on the nanosensor surface, to the target molecule, resulted in a direct piezoelectric effect, meaning the increase in the concentration and binding of the target molecule caused the measured output piezoelectric voltage of the nanowires due to the high degree of bending of the nanowires. Electronic circuits were simulated and built for an easy and inexpensive way to measure the piezoelectric voltage from the nanosensor, without having to use expensive equipment. The electronic circuit was successfully used to measure the piezoelectric voltage from the nanosensor. The biosensor was successfully fabricated and tested as a proof of concept, the chosen biotin-probe was the anti-luteinizing hormone-ß to detect the luteinizing hormone present in our bloodstream. An increase in piezoelectric potential were due to an increase in antibodies concentration bound to the sensor surface, and this evidence shows that the ZnO nanosensor may be used to record changes in antibody concentrations. The recorded concentrations of the anti-luteinizing hormone-ß were ranging from 25 to 10 ng/µl.

AFRIKAANSE OPSOMMING: Tuberkulose (TB) word beskryf as een van die top 10 dodelike infeksiesiektes in die wêreld en miljoene mense kontrakteer en sterf van TB elke jaar. TB diagnose is een van die belangrikste aspekte om TB te beheer en te beëindig. Die huidige toetsmetodes vir TB-infeksie is baie duur, nie-draagbaar en laboratoriumgebaseerd. Dit vereis ervare personeel, is nie baie akkuraat nie, en het nie die vermoë om op dieselfde dag resultate by versorging te genereer nie. Dit verleng dus die tyd van diagnose tot behandeling onnodig. In hierdie projek word gepoog om 'n laekoste, draagbare, elektroniese biosensor vir die vroeë opsporing van Tuberkulose te ontwerp en te implementeer. 'n Biotien-gewysigde probe word gekoppel deur middel van die nie-kovalente interaksie van streptavidien-biotien en geïmmobiliseer op 'n sinkoksied (ZnO) nanosensor. Streptavidien- en biotien-immobilisering is bestudeer en bevestig met behulp van 'n Fourier Transform Infrared (FTIR) metode. Die ZnO nanodrade is gegroei en geöptimaliseer met behulp van 'n elektrochemiese deposisietegniek, wat gehelp het om die c-as-belyning van die nanodrade te verbeter. Die ZnO nanodrade is gekarakteriseer deur 'n skandering-elektronmikroskopie (SEM). Probe-immobilisering is bestudeer en bevestig met behulp van atoomkragmikroskopie (AFM) asook die piësoëlektriese respons van die nanosensor self. Die hoë affiniteit van die gebiotinileerde probe, geïmmobiliseer op die nanosensor oppervlak, met die teikengroep, het 'n direkte piësoëlektriese effek tot gevolg gehad, wat beteken dat die toename in die konsentrasie en binding van die teikenmolekule veroorsaak het dat die gemete uitset piësoëlektriese spanning van die sensor veroorsaak was as gevolg van die hoë mate van buiging van die nanodrade. Elektroniese stroombane is gesimuleer en gebou as 'n maklike en goedkoop manier om die piësoëlektriese spanning van die nanosensor te meet, sonder om duur toerusting te gebruik. Die elektroniese stroombaan is suksesvol gebruik om die piësoëlektriese spanning van die nanosensor te meet. Die biosensor is suksesvol vervaardig en getoets as 'n bewys van konsep. Die gekose biotien probe was die anti-luteïniserende hormoon - ß om die luteïniserende hormoon teenwoordig in ons bloedstroom op te spoor. Die toename in piësoëlektriese potensiaal was te wyte aan 'n toename in teenliggaamkonsentrasie gebonde aan die sensor oppervlak, en dit bewys dat die ZnO nanosensor gebruik kan word om veranderinge in antiliggaam konsentrasies te registreer. Die gemete konsentrasies van die anti-luteïniserende hormoon - ß het gewissel van 25 tot 10 ng / µ l.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/106001
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