| The contamination of ground and drinking water by pesticides is a very serious problem that must be monitored, as many pesticides are toxic to both humans and the environment. Many pesticide sensors have been developed, but are often expensive or complicated to manufacture. In an effort to develop an inexpensive, easily manufactured, and reliable biosensor for pesticides in water, this study outlines a procedure for harvesting intact mitochondria from cultivated Saccharomyces cerevisiae yeast cells and immobilizing the intact mitochondria on a high surface area carbon electrode for detection of pesticides. Most pesticides' mode of action is through the mitochondria, inhibiting one or more complexes in the electron transport chain (ETC). In this study, measurable current response can be obtained from the immobilized functioning mitochondria in the presence of pyruvate. The pesticide can be detected by a decrease in this measured response due to inhibition. When introduced to each of five common pesticides (2,4-dichlorophenoxyacetic acid (2,4-D), parathion, paraquat, permethrin, and atrazine), a statistically significant drop in current was seen as the ETC was interrupted. So far, inhibition has been seen with pesticide concentrations of 0.7 mg/L (2,4-D), 10 mg/L (parathion), 12.2 mg/L (paraquat), saturated (permethrin), and 5 mg/L (atrazine).;The final goal of this project was to characterize microelectrodes for use in microfluidic lab-on-a-chip biosensor devices. Because microfluidic systems tend to provide a multitude of advantages over bulk systems (i.e. faster response time, high reproducibility, portability, etc.), we began characterizing various epoxy-embedded microelectrodes for their compatibility with the pesticide system described above. From what was accomplished in this study, it was determined that the ideal microelectrode would be a gold pillar array made by electrodepositing a 50:50 solution of AuCN:AgCN, followed by a capping step with a pure AuCN solution. |
