| dc.description.abstract | Toxins are biological molecules observed in water resources, harmful to animal and human
life. They are produced by certain algae and can find their way to the human body
by drinking contaminated water, recreational water activities, or consuming contaminated
crops or fish. Identification of these toxins in water resources becomes an essential part
of the food industry and water quality analysis, creating an immediate need for an easy,
portable, and rapid detection. Developing biosensors using immunological principles removes
the need for complex and tedious analytical analysis while enabling sensitive and
specific detection of biological molecules, such as toxins. The advent of microfluidic devices
further simplifies the analysis and allows for rapid, automated, and in-field detection. The
combination of biosensors with microfluidic devices preserves the advantages but overcomes
the limitation of standard analysis methods.
The aim of this thesis is to first closely investigate the flow of the solution inside the
microfluidic channel to develop a new computational model. Design and fabrication of
microfluidic devices and implementation of immunoassay is a time-consuming process, and
optimization of every aspect of the experiment is not feasible. A valid computational model
can expedite the design and optimization process. In the next step, we showcased the use
of the optimized microfluidic design for quick, in-field monitoring of cyanotoxins in water
resources.
We present a novel bead-based competitive fluorescent assay using Quantum Dots
(QDs) as a reporter agent for multiplexed detection of two types of toxins: Okadaic Acid
(OA), a marine toxin, and Microcystin-LR (MC-LR), a freshwater toxin. To ease and
automate the detection process, a reusable microfluidic device, Toxin-Chip, was designed
and validated. It consists of (1) micromixer to mix and incubate the target toxin with
the detection reagent, (2) detection chamber to magnetically retain beads for downstream
analysis. The emitted signal from QDs captured on beads is proportional to the amount
of toxin in the solution. An image recognition program was developed to carry out the
signal read-out of microscopic images of the detection chamber. Two toxins were analyzed
on the microfluidic chip, and the device exhibited a low limit of detection (LOD). The
bead-based platform also showed remarkable chemical specificity against potential interfering
toxins. The device’s performance was tested and validated using natural lake water
samples from Columbia Lake of Waterloo contaminated with cyanotoxins. The Toxin-Chip
holds promise as a versatile and simple quantification tool for multiplexed field-based cyanotoxin
detection, with the potential of extension for the simultaneous detection of more
targets. | en |
