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Quantification of Foodborne Bacteria Using a Distance-Based Microfluidic Chip with Retroreflective Particular Probes

  • 박수아 (아주대학교 일반대학원)

초록/요약

Foodborne pathogens present a major threat to human health annually, driving the need for rapid on-site detection technologies. However, traditional agglutination-based assays are unsuitable for quantitative analysis, and enzyme- linked immunosorbent assay is limited by its complexity and time consumption. In this study, we aimed to develop a quantitative agglutination assay platform using a simple microfluidic chip to target one of the most important foodborne pathogens, Escherichia coli O157:H7. The chip was fabricated by bonding plasma-treated polydimethylsiloxane to a transparent glass substrate, while maintaining hydrophilicity to facilitate fluid flow without the need for an external energy source. The chip patterning was designed for distance-based signal counting, allowing for analysis by observing where the signals disappear. Visible signals were generated using retroreflective Janus particles (RJPs) as optical probes. Anti-E. coli antibodies were immobilized onto RJPs. When these RJPs were mixed with an E. coli sample, relatively larger aggregates formed proportionally to E. coli cell concentration, reducing the number of individual particles. Once this pre-mixture was introduced into the chip, the RJP-E. coli complexes settled onto the glass substrate based on size owing to gravity. Sedimented RJPs appeared as white dots as they are micro-sized particles that reflect the full wavelength range of visible light via retroreflection. Therefore, higher E. coli cell concentrations led to shorter signal appearances, enabling quantitative detection by the naked eye and a simple optical system.

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목차

1. Introduction 1
1.1 Importance of detecting Escherichia coli O157:H7 1
1.2 Standard methods for detection of E. coli 4
1.3 Sensing strategy of a novel E. coli detection system 6
1.4 Aim of the study 11
2. Materials and methods 12
2.1 Reagents and apparatus 12
2.2 Fabrication of sensing chip 13
2.3 Use of RJPs as an optical probe 16
2.4 Preparation of E. coli sample 17
3. Results and discussion 18
3.1 Chip design 18
3.2 Verification of optical signaling probe 21
3.3 Confirmation of the developed optical sensing principle 24
3.4 Image-processing algorithm for data digitization 27
3.5 Optimization of RJP concentration 30
3.6 Quantitative analysis of E. coli detection with the naked eye 33
3.7 Quantitative analysis of E. coli detection using an optical system 36
3.8 Comparison of Analytical Performance with a Commercial ELISA Kit 39
4. Conclusions 41
5. References 42

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