The development of a ZnO nanoforce biosensor for mortalin - a novel biomarker for Parkinson’s Disease

Naicker, Semai (2022-04)

Thesis (MEng)--Stellenbosch University, 2022.

Thesis

ENGLISH ABSTRACT: Parkinson’s disease, affecting 0.5 to 1% of persons aged 65 to 69 and up to 3% of persons aged 80 and older [1], is currently incurable. The typical diagnosis of Parkinson’s disease is performed clinically, after the onset of symptoms, which means that progressive symptoms must be controlled, as opposed to the possibility of prevention of symptoms. Mortalin protein, a participant in various essential physiological functions, has been found to be down-regulated in the blood serum of Parkinson’s disease patients and can be identified as an indicative biomarker for Parkinson’s. With a biosensor for Mortalin, the antigen’s concentration levels can be detected from early life stages. This introduces the prospect of preventative measures being put into place, to reduce the severity of Parkinson’s disease symptoms that may develop at a later stage. Therefore, the aim of this thesis was to develop a biosensor with the ability to detect the concentration levels of Mortalin in a biological sample. This was achieved through the development of a ZnO nanowire-based nanoforce biosensor. An electrochemical deposition process, for the deposition of well-aligned, c-axis orientated nanowires on Silicon substrates, was optimised. The nanowire array was further developed into a ZnO nanowire-based nanogenerator, and anti-Mortalin antibodies were immobilised onto the surface, using a Cysteamine self-assembled monolayer and a Glutaraldehyde cross-linker. The final biosensor was realised by addition of an electronic measurement system, in the form of signal amplification and appropriate conditioning, to reduce noise and amplify the small signals generated by the nanowires. The nanoforce biosensor was tested with biological samples (solutions of Mortalin antigen in PBS) of different concentrations, and the response of the biosensor, due to the addition of each sample, was recorded. The changes in voltage, observed in the different responses, were compared and it was found that the magnitude of the response correlates with the Mortalin concentration level in the biological sample, although no clear proportionality was observed. Therefore, it was concluded that the Mortalin nanoforce biosensor was successfully able to detect the Mortalin antigen concentration. However, further testing needs to be performed to determine the relationship between the voltage response and the Mortalin concentration.

AFRIKAANSE OPSOMMING: Geen behandeling bestaan tans vir Parkinson-siekte nie, wat 0.5 tot 1% van alle mense tussen die ouderdom van 65 en 69, en 3% van dié ouer as 80, affekteer. Die siekte word huidiglik slegs klinies gediagnoseer na die aanvang van simptome. Dit was onlangs bevind dat mortalien, ’n proteïen wat in menigde noodsaaklike fisio logiese prosesse deelneem, afgereguleer word in die bloed serum van diegene met Parkinson-siekte, asook dat dit as ’n voorspellende biomerker gebruik kan word vir die diagnose van Parkinson-siekte. Die doel van hierdie tesis was om ’n biosensor te ontwikkel om die konsentrasie van mortalien in ’n biologiese monster te meet. Hierdie doel was bewerkstellig deur die gebruik van ’n sinkoksied nanodraad-gebaseerde biosensor. Om so sensor te ontwikkel, was ’n elektrochemiese proses aanvanklik geoptimeer vir die groei van belynde, c-as geörienteerde, nanodrade op ’n intrinsieke silikon substraat. Om die vervaardigde nanodrade as biosensor te gebruik, was dit in ’n nanogenerator omgeskakel deur teenliggaampies op die nanodrade te immobiliseer deur middel van ’n sisteamien self-georganiseerde monolaag en glutaaraldehied kruiskoppeling. Verder, was die finale biosensor gerealiseer deur die gebruik van elektroniese meet komponente, in die vorm van seinversterking en gepaste kondisionering om ontslae te raak van ruis en die bruikbare sein na vore te bring uit die lae potensiaalverskille geïnduseer deur hierdie soort nanogenerator. Die bogenoemde biosensor het daarin geslaag om die konsentrasie van mortalien in biologiese monsters in beplande toetse te meet.

Please refer to this item in SUNScholar by using the following persistent URL: http://hdl.handle.net/10019.1/124630
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