Biomolecule nanosensing : model study in use of DNA aptamers in biosensing of ochratoxin A

• Main Author: Pang, Jonathan Kia Wui
• Other Authors: Alessandra Bonanni
• Format: Final Year Project
• Language: English
• Published: 2018
• Subjects: DRNTU::Science::Chemistry::Analytical chemistry::Nucleic acids
• Online Access: http://hdl.handle.net/10356/76189
• Institution: Nanyang Technological University

Ochratoxin A is a common secondary metabolite generated through respiratory processes of multiple species of moulds. It poses multiple health risks to both human and animal species upon consumption of contaminated foodstuff, resulting in in vivo necrotic and immunosuppressant effects upon contact with target organs. Experiments involved in this study were performed with the objective of generating an optimised methodology of biosensing for Ochratoxin A using fluorescent-labelled DNA aptamers as signal transduction element, and Blue Luminescent Graphene Quantum Dots as the sensing platform for improved sensitivity. 3 regioisomers of the same aptamer DNA sequence (with the 6-carboxyfluorescein (FAM) fluorescent tag located along different regions of their oligonucleotide chain) were investigated with all sequences displaying optimal fluorescence output at the excitation wavelength of 460 nm. Regioisomer 5’- GAT CGG GTG T/iFluorT/G GTG GCG TAA AGG GAG CAT CGG ACA - 3’ was found to provide the best sensitivity during preliminary trials conducted. Upon construction of the calibration model, a linear relationship between signal sensitivity and Ochratoxin A concentration in incubated samples was found to exist only at higher trace composition levels, whereas concentrations below 5 μM did not conform to this trend. This highlights the need for additional contemporary analytical techniques and theoretical physicochemical models to be employed in conjunction with the investigated protocol for trace and ultratrace sensing of Ochratoxin A in sample matrices.