COUPLING IMMUNOFLUORESCENCE AND OPTOELECTROKINETIC TECHNIQUE FOR ESCHERICHIA COLI DETECTION AND QUANTIFICATION IN WATER

摘要

At least 2 billion people worldwide drink water from sources contaminated with feces, in other words, sources contaminated with E. coli. The traditional method for detecting E. coli, among other limitations, detects only culturable bacteria and takes about 24 - 48 hours to yield a result. Consequently, the aim of this work is to develop a rapid diagnostic procedure for E. coli by combining immunofluorescence and optoelectrokinetic patterning to specifically target and sensitively trap the whole organism. This is to ensure the populace have timely access to sustained "E. coli-free " water for both domestic and recreational activities. The procedure involves conjugation of streptavidin functionalized superparamagnetic fluorescent micro-beads with biotin-labelled anti- E. coli polyclonal antibody. The conjugate is introduced into a water sample containing E. coli among other contaminants, where it specifically and sensitively targets the bacteria in the sample solution which is quantified using an optoelectrokinetic patterning technique by introducing the targeted organism in a fabricated microfluidic chip and trapping it with an application of both laser beam and AC electric field simultaneously. Preliminary experiments have shown that increasing concentrations of E. coli in the microfluidic chamber varies directly with the electrical resistance of the entire system. This on-going research has the potential of sensitively isolating E. coli from a large pool of organic and inorganic contaminants in water in less than 4 hours.