Abstract
The presence of bacterial pathogens in water can lead to severe complications such as infection and food poisoning. This research proposes a point-of-care electroosmotic flow driven microfluidic device for rapid isolation and detection of E. coli in buffered solution (phosphate buffered saline solution). Fluorescent E. coli bound to magnetic microbeads were driven through the microfluidic device using both constant forward flow and periodic flow switching at concentrations ranging from 2 × 105 to 4 × 107 bacteria/mL. A calibration curve of fluorescent intensity as a function of bacteria concentration was created using both constant and switching flow, showing an increase in captured fluorescent pixel count as concentration increases. In addition, the use of the flow switching resulted in a significant increase in the capture efficiency of E. coli, with capture efficiencies up to 83% ± 8% as compared to the constant flow capture efficiencies (up to 39% ± 11%), with a sample size of 3 µL. These results demonstrate the improved performance associated with the use of the electroosmotic flow switching system in a point-of-care bacterial detection assay.
Highlights
Fluorescent E. coli bound to magnetic microbeads were driven through the microfluidic device using both constant forward flow and periodic flow switching at concentrations ranging from 2 × 105 to 4 × 107 bacteria/mL
Fluorescent images were taken to determine a calibration curve and the capture efficiency based on fluorescent intensity of magnetic microbeads (mMBs)-E. coli* complexes
Solutions with mMB-E. coli* complexes concentrations of 2 × 105, 2 × 106, 4 × 106, 2 × 107, and 4 × 107 bacteria/mL were tested in a microfluidic device using both the constant and switching flow protocols at an electroosmotic flow (EOF) voltage of 650 V
Summary
Fluorescent E. coli bound to magnetic microbeads were driven through the microfluidic device using both constant forward flow and periodic flow switching at concentrations ranging from 2 × 105 to 4 × 107 bacteria/mL. The use of mMBs is ideal for this application due to the ease at which they are isolated in the system using the external magnetic field, their high surface area-to-volume ratio that allows for availability of ample binding sits, and their ability to be adapted to target a multitude of different biomolecules[8,9,10]. These factors make magnetophoretic separation using mMBs a promising choice for use in a μTAS device that is both reliable and versatile in its application
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