Development of Biosensors to Detect

Biological Agents in Water Melissa Bui

Mentor: Dr. Christopher ChoiAgricultural and Biosystems EngineeringCollege of Agriculture and Life SciencesUniversity of Arizona/NASA Space Grant

2007-2008 Statewide SymposiumApril 19, 2008

Presentation Outline

The Issue at HandBenefits of using biosensorsMethodsKey Findings

The Issue at Hand

Arizona’s water distribution network is comprised of a grid of pipes

Entry points of the grid make it easy for contaminants to pollute the water

There is currently no real-time method for detecting contaminants in Arizona’s water supply

Benefits of using biosensors

Microfluidic device provides a faster method of detecting microbes than current methods (assays)

Uses less materials than traditional culture plate method

Faster detection Eliminating the problem before it affects the masses

Can be used to prevent bioterrorism

MethodsE. Coli was the microbe being detected Salt injected in 8.5 m pipe at a flow rate of 0.4

L/m for 10 seconds 1 mL of E. Coli (concentration greater than 109

CFU/mL) in 1 L dechlorinated water is injected Samples taken in set time intervals with a

fraction collector at downstream end of pipe Samples taken at critical time points were

analyzed using biosensor and cell culturing

Comparison of optical signals to cell counts and salt tracer data

Turbulent flow Laminar flow

Jin-Hee Han, PhD Student, University of Arizona

E. Coli counts and microfluidic signals

Jin-Hee Han, PhD Student, University of Arizona

Key Findings

Microfluidic signals showed same trends as E. Coli counts and salt tracer data

Data from culture counts and sensors signals corresponded after normalizing data

Detection limit of biosensor as low as 10 CFU/mL

Sensors detected sample concentration in 5 minutes, while culturing samples took at least 2 days

AcknowledgementsSupport provided by: Dr. Christopher

Choi, Dr. Jeong-Yool Yoon, Jin-Hee Han, and Dr. Ryan Sinclair

Figures courtesy of Jin-Hee Han