Search

The objective of this thesis is to quantitatively detect ochratoxin A (OTA) in Canadian grain by electrochemistry. To this end, two distinct sensing approaches were developed. In the first approach, a simple label-free sensor was designed to detect OTA. The oxidation mechanism of OTA was investigated using cyclic voltammetry (CV), and the impact of pH on the sensor's response to OTA was explored. Experimental design techniques were employed to optimize the analytical signal. OTA was successfully detected in wheat extracts using differential pulse voltammetry (DPV). The calculated analytical limit of detection (LOD) and limit of quantification (LOQ) were 57.2 nM and 190.6 nM, respectively. For the second approach, a gold electrode (GE) was modified with an OTA-specific aptamer to create a selective aptasensor. Methylene blue (MB) was linked to the aptamer, and the cathodic peak resulting from the reduction of MB at the aptasensor's surface was recorded as the analytical signal using square wave voltammetry (SWV). The surface packing density of the sensor was calculated to optimize the OTA aptamer concentration during sensor modification. The proposed aptasensor detected OTA in phosphate-buffered saline (PBS) media with a lowest measurable concentration (LMC) of 3.44 µM and a lowest quantifiable concentration (LQC) of 10.42 µM. The aptasensor demonstrated its capability to detect OTA in spiked wheat extracts with acceptable accuracy. The thesis concludes by comparing the two developed methods and discussing future research opportunities to enhance the performance of the aptasensor.