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Jeon J.-W.,Program for Bio Microsystem Technology | Kim J.-H.,Program for Bio Microsystem Technology | Lee J.-M.,SOL Inc. | Lee W.-H.,Siliconfile | And 3 more authors.
Biosensors and Bioelectronics

To realize an inexpensive, pocket-sized immunosensor system, a rapid test devise based on cross-flow immuno-chromatography was physically combined with a lens-free CMOS image sensor (CIS), which was then applied to the detection of the food-borne pathogen, Salmonella typhimurium (S. typhimurium). Two CISs, each retaining 1.3mega pixel array, were mounted on a printed circuit board to fabricate a disposable sensing module, being connectable with a signal detection system. For the bacterial analysis, a cellulose membrane-based immunosensing platform, ELISA-on-a-chip (EOC), was employed, being integrated with the CIS module, and the antigen-antibody reaction sites were aligned with the respective sensor. In such sensor construction, the chemiluminescent signals produced from the EOC are transferred directly into the sensors and are converted to electric signals on the detector. The EOC-CIS integrated sensor was capable of detecting a traceable amount of the bacterium (4.22×103CFU/mL), nearly comparable to that adopting a sophisticated detector such as cooled-charge-coupled device, while having greatly reduced dimensions and cost. Upon coupling with immuno-magnetic separation, the sensor showed an additional 67-fold enhancement in the detection limit. Furthermore, a real sample test was carried out for fish muscles inoculated with a sample of 3.3CFU S. typhimurium per 10g, which was able to be detected earlier than 6h after the onset of pre-enrichment by culture.© 2013 Elsevier B.V. Source

Kim H.-S.,Program for Bio Microsystem Technology | Cho I.-H.,Program for Bio Microsystem Technology | Seo S.-M.,Program for Bio Microsystem Technology | Jeon J.-W.,Program for Bio Microsystem Technology | And 2 more authors.
Materials Science and Engineering C

A plastic module for in situ immuno-magnetic concentration (IMC) was devised by engraving acrylics and physically combining the system with a rapid test device to detect foodborne pathogen. The IMC module-installed analytical system consisted of three compartments for magnetic separation, sample medium absorption, and analysis of the target microorganism. To experimentally simulate a practical situation, immuno-magnetic beads were prepared by coupling monoclonal antibodies specific to Listeria monocytogenes, which was used as a model analyte, to chemically functionalized beads. Under the optimal conditions, the IMC module condensed the medium by a factor of 100 (e.g., from 10 mL to 100 μL) within 5 min and enriched the microorganism by about 60-fold. This concentrated sample was then analyzed using two different analytical systems based on lateral flow, i.e., ELISA-on-a-chip and immuno-chromatographic assay, which had high detection capabilities, 3.6 × 10 2 and 6.6 × 10 3 cells mL - 1, respectively. Thus, the IMC module-installed biosensor system was able to sequentially condense a large sample volume and detect the presence of contaminants within, for example, 30 min. Therefore, this approach could be suitable for early screening of food products that may be contaminated with microorganisms. © 2011 Elsevier B.V. All rights reserved. Source

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