The monitoring of drinking water for indicators of fecal contamination is crucial for ensuring a safe supply. In this study, a novel electrochemical method was developed for the rapid and sensitive detection of Escherichia coli ( E. coli ) in drinking water. This strategy is based on the use of engineered bacteriophages (phages) to separate and concentrate target E. coli when conjugated with magnetic beads, and to facilitate the detection by expressing gold binding peptides fused alkaline phosphatase (GBPs-ALP). The fusion protein GBPs-ALP has both the enzymatic activity and the ability to directly bind onto a gold surface. This binding-peptide mediated immobilization method provided a novel and simple approach to immobilize proteins on a solid surface, requiring no post-translational modifications. The concentration of E. coli was determined by measuring the activity of the ALP on gold electrodes electrochemically using linear sweep voltammetry (LSV). This approach was successfully applied in the detection of E. coli in drinking water. We were able to detect 10 5 CFU mL −1 of E. coli within 4 hours. After 9 hours of preincubation, 1 CFU of E. coli in 100 mL of drinking water was detected with a total assay time of 12 hours. Thismore »
A High-Throughput Microfluidic Magnetic Separation (µFMS) Platform for Water Quality Monitoring
The long-term aim of this work is to develop a biosensing system that rapidly detects bacterial targets of interest, such as Escherichia coli, in drinking and recreational water quality monitoring. For these applications, a standard sample size is 100 mL, which is quite large for magnetic separation microfluidic analysis platforms that typically function with <20 µL/s throughput. Here, we report the use of 1.5-µm-diameter magnetic microdisc to selectively tag target bacteria, and a high-throughput microfluidic device that can potentially isolate the magnetically tagged bacteria from 100 mL water samples in less than 15 min. Simulations and experiments show ~90% capture efficiencies of magnetic particles at flow rates up to 120 µL/s. Also, the platform enables the magnetic microdiscs/bacteria conjugates to be directly imaged, providing a path for quantitative assay.
- Publication Date:
- NSF-PAR ID:
- 10177452
- Journal Name:
- Micromachines
- Volume:
- 11
- Issue:
- 1
- Page Range or eLocation-ID:
- 16
- ISSN:
- 2072-666X
- Sponsoring Org:
- National Science Foundation
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- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Publisher's Version of Record
- https://doi.org/10.3390/mi11010016
