On 18 June at 15:15 Edith Viirlaid will defend her doctoral thesis “Biosensing Pesticides in Water Samples”.
Senior Research Follower Toonika Rinken (PhD), Institute of Chemistry, University of Tartu
Senior Engineer Adama Marie Sesay (PhD), Harvard University, USA
The global use of pesticides has increased steadily over the past decades. Majority of the applied pesticides potentially contaminate water and soil, and can unfavourably affect biota. The aim of this study was to develop biosensors for the detection of two problematic pesticides - glyphosate (N-phosphonomethyl-glycine) and carbaryl (1-naphthyl N-methylcarbamate). Currently glyphosate is the most extensively used herbicide for weed and vegetation control. Carbaryl was widely used until the mid-2000s, and although carbaryl is banned in EU, it is still one of the most popular carbamate insecticides in the United States. Detection of pesticides is commonly carried out with chromatographic methods which allow achieving low limit of detection, but are time consuming and are not suitable for in-field analyses. In order to achieve capability for quick and on-site specific testing of pesticides, biosensors are regarded as an alternative option. We developed different biosensing platforms for the detection of carbaryl and glyphosate. The carbaryl biosensor was based on the detection of the inhibiting effect of carbaryl on the catalytic activity of soluble tyrosinase. The glyphosate biosensor was based on competitive immunoanalysis, which unlike inhibition - based biosensors allows very selective detection of the targeted analyte. We optimized detection protocols and tested the biosensors. The limit of detection for carbaryl was found to be 0.2 mg/l and for glyphosate in millimolar concentration range. The main advantage of the application of biosensors is the fact that the sample pre-treatment step is not required and the results are obtained in about half an hour. In addition, we studied options for the stabilization and concentration of glyphosate samples to improve the sensitivity of glyphosate biosensor and enhance the reliability of quantitative analyses of pesticides.