Maisela, Dorah2026-01-062026-01-062025https://hdl.handle.net/10566/21606Coronavirus disease 2019 (COVID-19) is among the most life-threatening infectious illnesses globally and has led to millions of hospital admissions and fatalities. Lack of Point-of-Care (PoC) diagnostic tools for COVID-19 delays control of the disease, predominantly in resource-limited areas, and is linked to significant economic impact. Therefore, there is a need for simple, rapid, accurate, and affordable POC diagnostics to detect active COVID-19 early enough for favourable interventions. To develop COVID-19 detection tools that will constitute such diagnostics, our research group recently selected ssDNA aptamers that bind to COVID-19 biomarkers; Spike (S) and Nucleocapsid (N) proteins. Aptamers are highly specific synthetic nucleic acid ligands that are frequently described as “chemical antibodies”, with particularly desirable features relative to antibodies, and have shown great predictions in diagnostic applications. The aim of this study was to develop an aptamer-based detection assay for possible PoC diagnosis of COVID-19. The aptamers were selected using in silico approach and their secondary structures were predicted by RNAfold and RNA composer web servers. The binding interactions and energies of aptamer-biomarker complexes were characterised by molecular dynamic (MD) simulations. Gold nanoparticles (AuNPs) were synthesised using the Turkevich technique and characterised by ultraviolet-visible (UV-Vis) spectroscopy, dynamic light scattering (DLS), and high-resolution transmission electron microscopy (HR-TEM). The aptamers were conjugated to AuNPs, and the conjugates were characterised by UVVis spectroscopy. The aptamer-AuNPs conjugate was then used in the preparation of lateral flow (LF) test strips for the detection of N-protein (NP) and S-protein (SP). Three aptamers for each protein were selected and found to be stable with less minimum free energies, potentially high binding affinity (docking score) to their targets, great stability and compactness, with less amino acid residues fluctuating, and this was validated by experimental studies.enAntibodiesAptamerCoronavirus disease 2019Gold nanoparticlesLateral flow assayThesis