Biosensors for Detecting Genetically Modified Organisms in Food and Feed

The detection of genetically modified organisms is of growing interest given their considerable presence in vast variety of food and feed ingredients, as well as their environmental impact. In this study we demonstrate real-time, label- free detection of DNA from genetically modified, Roundup Ready (RR) soybeans by surface plasmon resonance (SPR). Two single stranded (ss) DNA sequences were employed: 1) a thiol labeled (5'- SH) oligonucleotide allowing oriented covalent immobilization to the gold surface of the sensor which served as an anchor, and 2) probe sequence targeting the promoter of the (CaMV 35S) 5-enolpyruvylshikimate-3-phosphate synthase (EPSPS) gene present in RR soybeans. Our data indicate the limit of detection was as low as 2.0 nM. The system was also interrogated with target and non-target oligomeric mix and showed significant degree of specificity and selectivity. No binding was observed with non-target oligo injections. The sensitivity was as low as 8.0 nM when the target was in an excess mix of non-target sequences. This is the first step in developing a highly sensitive method for direct, label-free detection of genomic DNA from food products containing GMO soybeans.