Limits...
Lab-on-a-chip pathogen sensors for food safety.

Yoon JY, Kim B - Sensors (Basel) (2012)

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Agricultural and Biosystems Engineering, the University of Arizona, Tucson, AZ 85721, USA. jyyoon@email.arizona.edu

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.

Show MeSH

Related in: MedlinePlus

Latex immunoagglutination assay—formation of a doublet or bigger clumps through multiple epitope binding. Reprinted from [47] with permission © American Society of Agricultural and Biological Engineers.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC3472853&req=5

f8-sensors-12-10713: Latex immunoagglutination assay—formation of a doublet or bigger clumps through multiple epitope binding. Reprinted from [47] with permission © American Society of Agricultural and Biological Engineers.

Mentions: There is another simpler format of immunoassay that can be reproducibly demonstrated in lab-on-a-chip, called latex immunoagglutination assay (LIA). Although this is not label-free, it is potentially rinse-free (both ELISA and SPR lab-on-a-chips require rinsing steps). In LIA, particles are coated with antibodies to a given target and mixed with the sample fluid in question. If the antigen is present in the fluid, the particles form larger aggregates (more precisely, agglutinates) due to antibody-antigen interactions, termed immunoagglutination (Figure 8) [47]. In the past, this has been detected visually, with the detection limit being the point at which agglutinates precipitate and become visible; however, measuring the immunoagglutination via forward light scattering in a lab-on-a-chip is more appropriate [48], as agglutinated submicron or nanoparticles are not required to precipitate out of solution for a positive signal [49,50]. Yoon's research group has primarily investigated LIA in lab-on-a-chip [51–56]. Particles with a diameter near the wavelength of visible light were used, i.e., in the regime of Mie scattering, whose scattering intensity is not only very strong but also depends largely on the size and morphology of particles [57–59]. In the presence of target antigens, the microparticles agglutinate, effectively increasing the particle diameter, thus increasing the intensity of scattered light. In this way, a blank signal (antibody conjugated particles in solution without target) can be recorded and compared to scattering intensities from solutions with known concentrations of target antigen, and a standard curve can be constructed. Heinze et al. [58] detected avian influenza virus with the detection limit of 10 pg/mL in 1% diluted chicken feces. You et al. [59] detected E. coli with the detection limit of 10 CFU/mL in 10% diluted lettuce. Fronczek et al. [60] detected Salmonella with the detection limit of 10 CFU/mL in 10% diluted chicken tissue, all with the assay time of 10 minutes or less.


Lab-on-a-chip pathogen sensors for food safety.

Yoon JY, Kim B - Sensors (Basel) (2012)

Latex immunoagglutination assay—formation of a doublet or bigger clumps through multiple epitope binding. Reprinted from [47] with permission © American Society of Agricultural and Biological Engineers.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3472853&req=5

f8-sensors-12-10713: Latex immunoagglutination assay—formation of a doublet or bigger clumps through multiple epitope binding. Reprinted from [47] with permission © American Society of Agricultural and Biological Engineers.
Mentions: There is another simpler format of immunoassay that can be reproducibly demonstrated in lab-on-a-chip, called latex immunoagglutination assay (LIA). Although this is not label-free, it is potentially rinse-free (both ELISA and SPR lab-on-a-chips require rinsing steps). In LIA, particles are coated with antibodies to a given target and mixed with the sample fluid in question. If the antigen is present in the fluid, the particles form larger aggregates (more precisely, agglutinates) due to antibody-antigen interactions, termed immunoagglutination (Figure 8) [47]. In the past, this has been detected visually, with the detection limit being the point at which agglutinates precipitate and become visible; however, measuring the immunoagglutination via forward light scattering in a lab-on-a-chip is more appropriate [48], as agglutinated submicron or nanoparticles are not required to precipitate out of solution for a positive signal [49,50]. Yoon's research group has primarily investigated LIA in lab-on-a-chip [51–56]. Particles with a diameter near the wavelength of visible light were used, i.e., in the regime of Mie scattering, whose scattering intensity is not only very strong but also depends largely on the size and morphology of particles [57–59]. In the presence of target antigens, the microparticles agglutinate, effectively increasing the particle diameter, thus increasing the intensity of scattered light. In this way, a blank signal (antibody conjugated particles in solution without target) can be recorded and compared to scattering intensities from solutions with known concentrations of target antigen, and a standard curve can be constructed. Heinze et al. [58] detected avian influenza virus with the detection limit of 10 pg/mL in 1% diluted chicken feces. You et al. [59] detected E. coli with the detection limit of 10 CFU/mL in 10% diluted lettuce. Fronczek et al. [60] detected Salmonella with the detection limit of 10 CFU/mL in 10% diluted chicken tissue, all with the assay time of 10 minutes or less.

Bottom Line: 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.

View Article: PubMed Central - PubMed

Affiliation: Department of Agricultural and Biosystems Engineering, the University of Arizona, Tucson, AZ 85721, USA. jyyoon@email.arizona.edu

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.

Show MeSH
Related in: MedlinePlus