Microfluidic sampling and biosensing systems for foodborne Escherichia coli and Salmonella

Authors: WANG, BIN - Oak Ridge Institute For Science And Education (ORISE); Park, Bosoon

Submitted to: Foodborne Pathogens and Disease
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/27/2022
Publication Date: 6/10/2022
Citation: Wang, B., Park, B. 2022. Microfluidic sampling and biosensing systems for foodborne Escherichia coli and Salmonella. Foodborne Pathogens and Disease. https://doi.org/10.1089/fpd.2021.0087.
DOI: https://doi.org/10.1089/fpd.2021.0087

Interpretive Summary: The outbreaks of public health crisis caused by foodborne bacteria and other pathogens have shown the importance of monitoring low concentration of pathogens in food samples where they are processed, transported, and sold to consumers. Conventional detection methods are based on cell culture or molecular biology, which require sophisticated instruments and highly skilled professionals. Biosensors with small size and easy operation have been developed, but their sensitivity and specificity are limited. Microfluidic methods provide the opportunity to test bacteria sample solution at micrometer or single cell level, so the instruments can be simplified and reduced to a much smaller size. Therefore, less sample are needed, more functions can be realized within one platform, resulting in low cost. The microfluidic methods can be directly connected to various biosensing platforms and in turn improve sensitivity. This paper introduces major types of microfluidic devices according to working mechanisms for enriching and separating bacteria from sample solution. Three major fabrication methods were discussed with their advantages and limitations for microfluidic devices. The applications of microfluidic methods to improve bacteria biosensing in recent years were summarized, especially, enrichment and detection of E. coli and Salmonella were discussed. Since the small size and non-spherical shape of bacterial cells make them more difficult to predict and control when passing through the microfluidic devices, it is challenging to use microfluidic devices for real-world samples. More studies are needed to develop microfluidic fabrication and testing methods that can provide rapid response to foodborne outbreaks.

Technical Abstract: The outbreaks of foodborne pathogen diseases and public health crisis have stimulated the development of portable biosensors for the field-deployable and point-of-care detections. Conventional bacteria cultivation and gene amplification methods require sophisticated instruments and highly skilled professionals. Although portable biosensing devices are capable of rapid field detections, their sensitivity and specificity are limited. Microfluidic methods exploit unique biophysical properties of fluids and different biospecies at micrometer or single cell level, so they obtain advantages of miniaturizing instrumental size and sample consumption while integrating multiple functions into one streamline system with low cost. Therefore, microfluidic sampling methods coupled with biosensors can improve quantitative measurement and bacteria manipulation by reducing background interference and increasing the ratio of functional interface of the device to the targeted biospecies. This paper introduces the major active and passive microfluidic devices that have been used for bacteria sampling and biosensing. The emphasis is on the particle-based sorting/enrichment methods with or without external physical fields applied to the microfluidic devices, and various biosensing applications reported for bacteria sampling. Three major fabrication methods for microfluidics were briefly discussed with their advantages and limitations. The applications of active and passive microfluidic sampling methods recently developed were summarized focused on E. coli and Salmonella. The current challenges on microfluidic bacteria sampling are caused by the small size and non-spherical shape of various bacterial cells, which can induce unpredictable deviations in sampling and biosensing processes. Further studies are needed to develop prototyping methods that can provide rapid response to various pathogen outbreaks.