| UC Toxics News: Winter
2005
Organophosphates (OPs) are widely used toxic nerve agents found in agricultural pesticides, household products, and chemical warfare agents. Although OPs are touted for their biodegradability and short life, they are acutely toxic and their sheer scale of use poses problems for our food and water supplies. Current detection and monitoring technology consists of taking samples in the field and shipping them to a lab for analysis. But that's about to change. Joseph Cooke, a graduate student in UC Riverside's Chemical and Environmental Engineering Program, has received a TSR&TP fellowship to develop a dynamic nanoscale biosensor array that can detect and quantify a broad range of OP compounds. This array will provide instant feedback and lead to a more cost-effective method of environmental monitoring. "We need new sensor technologies to protect our food and water supplies", says Cooke. "In the long run, if we want to optimize water and pesticide use in the field for the greatest efficiency and economic return, we have to understand transport issues and we need sensor technology to do this." The biosensor is designed with polydimethylsiloxane (PDMS), a polymer that can be molded easily without the need for clean room facilities. The research group used recombinant DNA techniques to combine the PDMS with organophosphorus hydrolase enzyme variants and then patterned them onto a microarray surface. This design is a reversible and reusable platform. "MEMs (microelectromechanical systems) devices are typically expensive", explains Cooke. "To use these devices in environmental monitoring, it has to be cost-effective." This array is especially useful in the field because it is small (about 1 inch by 1 inch) and there's no need to send samples back to a lab since the lab-on-a-chip does the analysis. Their design brings the idea of preventive monitoring closer to reality. Using enzyme variants developed for their enhanced sensitivity to OPs could make the biosensor significantly more sensitive than any detection technology currently available. The array has been tested down to 100 picomolar concentrations with coumaphos, a common OP pesticide in agriculture. Further testing is planned. UC Riverside is currently building an electronics fabrication facility, and once this is complete, the group will work on powering their lab-on-a-chip. Because some of the same enzymes in the microarray can be used for detecting chemical warfare agents, the group's research could potentially provide real time sensing of chemicals in the air, water, and ground. "Developing this sensor array technology is very important not only for environmental monitoring," says Cooke, "but for homeland security as well. There's an immediate need to be able to detect toxins at low levels in the US and in the rest of the world." Cooke says the funding he received from the TSR&TP and presenting his project at the program's Symposium in San Diego "enabled me to see how my research fits into the whole picture, as well as some of the other aspects of the area and applications that I was not familiar with. It's been a good opportunity." |
