|BALSAM, JOSH - Food And Drug Administration(FDA)|
|Hernlem, Bradley - Brad|
|RASOOLY, AVRAHAM - Food And Drug Administration(FDA)|
Submitted to: Biosensors and Bioelectronics
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 1/28/2015
Publication Date: 1/29/2015
Publication URL: http://handle.nal.usda.gov/10113/60829
Citation: Rasooly, R., Balsam, J., Hernlem, B.J., Rasooly, A.J. 2015. Sensitive detection of active Shiga toxin using low cost CCD based optical detector. Biosensors and Bioelectronics. 68:705-711.
Interpretive Summary: One of the factors limiting the widespread testing of foods for toxins causing food poisoning is the cost of equipment. This is particularly important in poorer parts of the world. We tested a simpler, less expensive system using a digital camera to measure an important food toxin and found it compares with equipment costing 100 times more. This method and finding will help make toxin testing more available where it is needed.
Technical Abstract: To reduce the sources and incidence of food-borne illness there is a need to develop inexpensive sensitive devices for detection of active toxin, such as Shiga toxin type 2 (Stx2). This approach increases the availability of foodborne bacterial toxin diagnostics in regions where there are limited resources. We evaluate a potential low cost (~$300) alternative to commercial fluorometers that are typically a couple orders of magnitude more expensive (~$30,000). In this study a simple fluorescence detection system was constructed using a charge-coupled device (CCD) camera and light emitting diode (LED) excitation source, to measure green fluorescent protein (GFP) in a cell based assay. The system was evaluated and compared to a commercial fluorometer for detecting active Stx2 in the range 100 ng/ml-0.01 pg/ml. The result shows that there is a linear relationship between active Stx2 concentrations and luminous intensity of the GFP, imaged by the CCD camera (R² = 0.85) or fluorometer (R² = 0.93). Both instruments have the same level of detection (LOD) of 0.1 pg/ml of Stx2. These results demonstrate the utility and the potential of low cost detectors for toxin activity; this approach could be readily adapted to the detection of other food-borne toxins.