State Water Resources Research Institute Program

Project ID: 2008CT170B
Title: Rapid and Sensitive Detection of Total Coliforms and E. coli Using SWNT Membrane
Project Type: Research
Start Date: 3/01/2008
End Date: 2/28/2010
Congressional District: #2
Focus Categories: Groundwater, Water Supply, Methods
Keywords: ground water, total coliforms, E.coli, amperometric biosensor
Principal Investigator: Lei, Yu (University of Connecticut)
Federal Funds: $ 25,696
Non-Federal Matching Funds: $ 51,980
Abstract: Waterborne microbiological contaminations remain one of the major threats to public health. The Centers for Disease Control and Prevention (CDC) have reported that each year, 4 billion episodes of diarrhea result in an estimated 2 million deaths, mostly among children. Waterborne bacterial infections may account for as many as half of these episodes and deaths. In addition, the USEPA recently promulgated the Groundwater Rule which is intended to provide for increased protection against microbial pathogens in public water systems that use ground water sources. This rule is expected to impact a number of groundwater systems in Connecticut leading to more sophisticated monitoring requirements for fecal indicators in groundwater used for drinking water purposes. However, currently EPA approved methods for total coliforms (TC) and E. coli are time-consuming and usually take 18-24 h to complete. From a public health standpoint, it is too long to announce a boil water notification if the sample is positive for total coliforms or E. coli. Thus, there exists an urgent need to develop fast, easy-to-use, and sensitive detection systems for total coliforms and E. coli. Preferably, these sensors have the potential to be used in houses by unskilled personnel for drinking water quality control.

This proposal aims at laying the foundation to filling the gap between need and availability by developing the technology required for a rapid, sensitive, and simultaneous detection of total coliforms and E. coli. A number of significant novel features will be introduced to the sensor system that promise to make it faster and fundamentally more sensitive toward our targets than existing technologies. First, a developed SWNT membrane will filter water sample and, thus, serve as bacteria concentrator, achieving the quick concentration and immobilization of bacteria on SWNT in a single step; second, the SWNT membrane also serves as working electrode in amperometric detection and enhances the sensitivity due to its super-electron conductivity, anti-fouling property, and strong electrocatalytic capability; third, two "electrogenic" substrates are specifically selected for beta-D-galactosidase (total coliforms) and beta-D-glucuronidase (E. coli) respectively, and the hydrolyzed products from enzymatical reactions have distinguishable oxidation potentials, allowing the simultaneous detection of total coliforms and E. coli possible. All these features make the proposed detection system a potentially ideal analytical tool for drinking water quality control.

Progress/Completion Report, 2009, PDF

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