Full Text Available
Note: Clicking the button above will open the full text document at the original institutional repository in a new window.
The development of a plasmonic based biosensor to assist in the diagnosis of anxiety and depression
Thesis (MEngSc)--Stellenbosch University, 2025.
Saved in:
| Main Author: | |
|---|---|
| Other Authors: | |
| Format: | Thesis |
| Language: | en_ZA |
| Published: |
Stellenbosch : Stellenbosch University
2025
|
| Subjects: | |
| Tags: |
No Tags, Be the first to tag this record!
|
| _version_ | 1867613882757939200 |
|---|---|
| access_status_str | Open Access |
| author | Tayob, Zahra |
| author2 | Perold, Willem J. |
| author_browse | Perold, Willem J. Tayob, Zahra |
| author_facet | Perold, Willem J. Tayob, Zahra |
| author_sort | Tayob, Zahra |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEngSc)--Stellenbosch University, 2025. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/132408 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:43:12.690Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2025 |
| publishDateRange | 2025 |
| publishDateSort | 2025 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/132408 The development of a plasmonic based biosensor to assist in the diagnosis of anxiety and depression Tayob, Zahra Perold, Willem J. Bosman, Gurthwin W. Engelbrecht, Anna-Mart Stellenbosch University. Faculty of Engineering. Dept. of Mechanical & Mechatronic Engineering. Plasmonics Biomedical industries Anxiety disorders -- Diagnosis Depression, Mental -- Diagnosis UCTD Thesis (MEngSc)--Stellenbosch University, 2025. Tayob, Z. 2025. The development of a Plasmonic based biosensor to assist in the diagnosis of anxiety and depression. Unpublished masters thesis. Stellenbosch: Stellenbosch University [online]. Available: https://scholar.sun.ac.za/items/540291cd-4d35-4810-9d04-7f24b7cac66d ENGLISH ABSTRACT: Anxiety and depression are increasingly common mental health disorders, frequently misdiagnosed in approximately 49 % to 75 % of cases, likely due to the subjective nature of consultation-based assessments. These conditions arise from a complex interplay of social, psychological, and biological factors, prominently affecting the hypothalamic-pituitary-adrenal (HPA) axis, where cortisol serves as a promising diagnostic biomarker. Traditionally, cortisol detection in laboratory settings relies on immunoassays such as ELISA, which is a labelled detection. Localised Surface Plasmon Resonance (LSPR) presents an alternative, label-free detection method that enhances sensitivity through optical resonance. LSPR is a phenomenon where incident light induces collective electron oscillations on metal nanoparticles, which is sensitive to refractive index changes, making it an ideal platform for biosensing applications. In this study, LSPR was achieved through the fabrication of Gold Nanoparticles (AuNPs) at room temperature with a gold precursor, Gold Chloride Trihydrate (HAuCl4.3H2O), and reducing agent, Sodium Formate (HCOONa). An iterative study of HCOONa concentrations revealed that 500 mM produced the strongest LSPR effect, indicating optimal coupling. The AuNPs were fabricated in a 96-well polystyrene plate, compatible with an established experimental setup, featuring a HL-200 broadband halogen light source and a compact CCS Series Spectrometer. To achieve cortisol detection, the AuNP film was functionalized using Cysteamine Hydrochloride and Glutaraldehyde, enabling the immobilisation of a monoclonal antibody to cortisol. This was validated through fluorescence microscopy, confirming successful antibody binding. Bulk sensitivity tests were conducted for various refractive index units (RIUs), which indicated a linear trend at isolated low RIUs (13.033 a.u/RIU) and high RIUs (2.320 a.u/RIU), suggesting promising bulk sensitivity. Surface sensing trials showed limited sensitivity to cortisol detection when using BSA-conjugated cortisol. While further refinement is needed to optimize surface sensitivity to cortisol, this study establishes a strong foundation for a plasmonic based biosensor to assist in diagnosing anxiety and depression. AFRIKAANSE OPSOMMING: Angs en depressie is toenemend algemene geestesgesondheidstoestande wat dikwels verkeerd gediagnoseer word in ongeveer 49 % tot 75% van gevalle, waarskynlik as gevolg van die subjektiewe aard van konsultasie-gebaseerde assesserings. Hierdie toestande ontstaan uit 'n komplekse wisselwerking van sosiale, sielkundige en biologiese faktore, wat veral die hipotalamus-pituïtêre adrenale (HPA) as beïnvloed, waar kortisol as 'n belowende diagnostiese biomerker dien. Tradisioneel berus kortisol-opsporing in laboratoriumtoestande op immunoasserings soos ELISA, wat 'n gemerkte opsporingsmetode is. Gelokaliseerde Oppervlak Plasmon Resonansie (LSPR) bied 'n alternatiewe, merklose opsporingsmetode wat sensitiwiteit deur optiese resonansie verhoog. LSPR is 'n verskynsel waar invallende lig kollektiewe elektron-ossillasies op metaal nanodeeltjies induseer, wat sensitief is vir brekingsindeksveranderinge, wat dit 'n ideale platform maak vir biosensortoepassings. In hierdie studie is LSPR behal deur die vervaardiging van goudnanodeeltjies (AuNPs) by kamertemperatuur met 'n goudvoorganger, goudchloriedtrihidraat (HAuCl₄.3H₂O), en 'n reduseermiddel, natriumformiaat (HCOONa). 'n Iteratiewe studie van HCOONa-konsentrasies het getoon dat 500 mM die sterkste LSPR-effek gelewer het, wat optimale koppeling aandui. Die AuNP's is vervaardig in 'n 96-put-polistiroplaat, wat versoenbaar is met 'n gevestigde eksperimentele opstelling, wat 'n HL-200 breëband-halogeenligbron en 'n kompakte CCS-reeks spektrometer insluit. Om kortisol-opsporing te behaal, is die AuNP-film gefunksionaliseer met behulp van sisteamienhidrochloried en glutaaraldehied, wat die immobilisering van 'n monoklonale kortisolteenliggaam moontlik gemaak het. Dit is deur fluoresserende mikroskopie gevalideer, wat suksesvolle teenliggaambinding bevestig het. Grootskaalse sensitiwiteitstoetse is uitgevoer vir verskeie brekingsindeks-eenhede (RIU’s), wat 'n lineêre tendens getoon het by geïsoleerde lae RIU’s (13.033 a.u./RIU) en hoë RIU’s (2.320 a.u./RIU), wat belowende grootskaalse sensitiwiteit suggereer. Oppervlak opsporingsproewe het beperkte sensitiwiteit vir kortisol-opsporing getoon wanneer BSA-gekonjugeerde kortisol gebruik is. Alhoewel verdere verfyning nodig is om oppervlakgevoeligheid vir kortisol te optimaliseer, lê hierdie studie 'n sterk grondslag vir 'n plasmoniese-gebaseerde biosensor om angs en depressie te help diagnoseer. Masters 2025-06-06T07:48:31Z 2025-06-06T07:48:31Z 2025-03 Thesis https://scholar.sun.ac.za/handle/10019.1/132408 en_ZA Stellenbosch University xiv, 101 pages : illustrations, includes annexures application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Plasmonics Biomedical industries Anxiety disorders -- Diagnosis Depression, Mental -- Diagnosis UCTD Tayob, Zahra The development of a plasmonic based biosensor to assist in the diagnosis of anxiety and depression |
| title | The development of a plasmonic based biosensor to assist in the diagnosis of anxiety and depression |
| title_full | The development of a plasmonic based biosensor to assist in the diagnosis of anxiety and depression |
| title_fullStr | The development of a plasmonic based biosensor to assist in the diagnosis of anxiety and depression |
| title_full_unstemmed | The development of a plasmonic based biosensor to assist in the diagnosis of anxiety and depression |
| title_short | The development of a plasmonic based biosensor to assist in the diagnosis of anxiety and depression |
| title_sort | development of a plasmonic based biosensor to assist in the diagnosis of anxiety and depression |
| topic | Plasmonics Biomedical industries Anxiety disorders -- Diagnosis Depression, Mental -- Diagnosis UCTD |
| url | https://scholar.sun.ac.za/handle/10019.1/132408 |
| work_keys_str_mv | AT tayobzahra thedevelopmentofaplasmonicbasedbiosensortoassistinthediagnosisofanxietyanddepression AT tayobzahra developmentofaplasmonicbasedbiosensortoassistinthediagnosisofanxietyanddepression |