Date

2014

Author

Bulut, Onur

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Foodborne diseases have been a crucial problem for the public health. Various agents transmitted by food cause these diseases. However, Salmonella accounts for most of the cases leading to most of the hospitalization and even death. Therefore, rapid detection of Salmonella is a considerable step in order to improve food safety and minimize outbreaks. Nucleic acid based biosensors are fast, simple, economic, easy-to-use and do not require trained personnel or high-cost equipments when compared to the current detection methods such as culture and molecular methods. In this study, a nucleic acid based biosensor called lateral flow immunochromatographic assay was developed as a rapid, sensitive, easy-to-use and economic detection system for Salmonella. vi Accordingly, a synthetic oligonucleotide was designed from invA gene which is found in most Salmonella serotypes. The synthetic oligonucleotide was used as the target in order to establish assay procedure and optimize the parameters including time, concentration and temperature. After optimization studies, real targets which were two different PCR products were applied to the assay as targets. The real target samples were 105 bp and 284 bp amplicons of invA gene. In order to form signal probes, AuNPs were functionalized with thiol-modified ssDNAs which were complementary to one part of the target. Biotinylated ssDNAs which were complementary to other part of the target were immobilized onto nitrocellulose membrane to create the capture probe on the test line. When the target was applied to assay, it firstly hybridized with signal probe and then migrated among the test strip. In the test zone, it was capture by the immobilized probe by forming sandwich-type hybridization which resulted in formation of naked eye detectable dark-red colored band. Lateral flow immunochromatographic assay developed in this study achieved detection of different Salmonella specific DNA sequences and it is a promising device for rapid, accurate, easy-to-use and low-cost detection systems.

Subject Keywords

Salmonella., Biosensors., Foodborne diseases., Salmonella, Pathogenic microorganisms.

URI

http://etd.lib.metu.edu.tr/upload/12617949/index.pdf
https://hdl.handle.net/11511/24044

Collections

Graduate School of Natural and Applied Sciences, Thesis