| Abstract |
Agriculture is vital to Thailand’s economy. However, the use of herbicides such as atrazine pose a
significant risk to human health, animals and the environment. These chemicals are designed to persist in
soil and on plants for weeks in order to stop weed growth, but as a result they can accumulate in plants and
water that human consume which in turn exposes us to unsafe levels of these chemicals (0.003 mg/L in
water; US Environmental Protection Agency). As a result, there is a need for accurate and sensitive
detection of atrazine. Current methods rely heavily on laboratory-based techniques, which are timeconsuming,
costly, and require trained operators to operate specialised equipment. Field-based methods
exist, but they are either non-specific (acetylcholinesterase) or have higher production costs and lower
component stability (antibodies). DNA aptamers are an interesting alternative as they are cheap to produce
and normally easy to convert into a field-testable format. However, the most sensitive existing atrazine
aptamer can only be used with laboratory-based isothermal titration calorimetry at present. In this work, a
strand displacement aptamer system is explored to overcome this limitation. A range of oligonucleotides
complementary of the aptamer are designed and the ability of atrazine to bind to the aptamer and displace
these complementary oligonucleotides is evaluated. Ultimately the goal is to modify the atrazine-specific
aptamer with a fluorescent dye at the 5' end. In the absence of atrazine, the aptamer hybridises with a
complementary DNA strand containing a quencher at the 3' end, resulting in fluorescence quenching. In the
presence of atrazine, the aptamer preferentially binds to the target molecule displacing the quencher
strand and leading to fluorescence emission. This strand displacement mechanism potentially enables the
direct and real-time detection of atrazine residues with high sensitivity and selectivity. |
Publication
Journal Publication
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