Abstract
There have been a number of cases of foodborne illness among humans that are caused by pathogens such as Escherichia coli O157:H7, Salmonella typhimurium, etc. The current practices to detect such pathogenic agents are cell culturing, immunoassays, or polymerase chain reactions (PCRs). These methods are essentially laboratory-based methods that are not at all real-time and thus unavailable for early-monitoring of such pathogens. They are also very difficult to implement in the field. Lab-on-a-chip biosensors, however, have a strong potential to be used in the field since they can be miniaturized and automated; they are also potentially fast and very sensitive. These lab-on-a-chip biosensors can detect pathogens in farms, packaging/processing facilities, delivery/distribution systems, and at the consumer level. There are still several issues to be resolved before applying these lab-on-a-chip sensors to field applications, including the pre-treatment of a sample, proper storage of reagents, full integration into a battery-powered system, and demonstration of very high sensitivity, which are addressed in this review article. Several different types of lab-on-a-chip biosensors, including immunoassay- and PCR-based, have been developed and tested for detecting foodborne pathogens. Their assay performance, including detection limit and assay time, are also summarized. Finally, the use of optical fibers or optical waveguide is discussed as a means to improve the portability and sensitivity of lab-on-a-chip pathogen sensors.
Highlights
Food is one of the most important resources for humans, but for microbes as well, resulting in many foodborne illnesses
O157:H7, Salmonella spp., Staphylococcus aureus, Campylobacter jejuni, and Listeria monocytogenes, which have been found in many different food samples in the past couple of decades [1,2,3,4]
The first such demonstration was made by Kopp et al, where a single serpentine microfluidic channel travels through three different temperature zones to achieve 20-cycle polymerase chain reactions (PCRs)
Summary
Food is one of the most important resources for humans, but for microbes as well, resulting in many foodborne illnesses. Certain bacterial pathogens can be cultured in a relatively simple manner, e.g., the sample liquid is diluted and spread on an agar plate, incubated for a day or two, and the number of colonies is counted This is inappropriate for early detection since it takes days to see the results. Enzymes and other reagents are added to it, followed by cycling through three different temperatures and repeating the cycles 20–40 times In this matter, the amount of a specific genetic sequence in a target pathogen can be amplified that can be detected by gel electrophoresis. The lab-on-a-chip-based biosensor is a perfect medium to make portable and real-time biosensing of foodborne pathogens possible. We will summarize the requirements of lab-on-a-chip biosensor for field applications, highlight a group of lab-on-a-chip biosensors, and their applications to foodborne pathogens
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