The objective for our project to be accomplished in the next three years is the demonstration of a procedure for the detection of pathogenic bacteria on the surface of vegetables and plants and a biosensor that is capable of detecting the binding of a single target species (spore or bacterium). <P>In the long term, we are seeing to develop miniaturized bacterial sensors capable of being incorporated into a stamp-size device and combined with RFID for the monitoring of bulk food shipments; to investigate the sensitivity and specificity of the prototype microchip sensors using model biological toxins, living pathogens, and spores; to determine the longevity/stability of these sensors in a food product environment; to develop miniaturized electronics for the RFID sensor tag devices; and to test the RFID sensor tag device in the field.
Non-Technical Summary: The U.S. food supply chain is one of the most complex delivery systems in the world. Ensuring the safety of the food from naturally occurring or deliberate acts of contamination is a national priority that affects all citizens of these United States. The principal impediments to identification and removal of unsafe food include the lack of rapid food pathogen detection methods, a cumbersome inventory-traceability system, and the inability to identify the source of the problem requiring correction. Recent instances of food contamination stemming from Salmonella contamination in the field (spinach and tomatoes) and during plant processing (peanuts) have emphasized the need for new detection methodologies. The research being conducted under this grant seeks to address these contaminations with introduction of the Magnetoelastic Phage-Based Biosensor. These biosensors are smaller than particles of dust, wireless, require no on-board power, are biodegradable, and are inexpensive. These biosensors may be sowed onto plants in the field and then analyzed to detect the presence of pathogens such as Salmonella or Bacillus anthracis on the leaves of crops such as spinach and tomatoes. New phage-based detection technologies with anticipated detection limits several orders of magnitude better and with shelf-lives up to five times longer are also being investigated. The goal is to improve our ability to detect naturally or deliberate contaminations of our food supply through improved sensor and information technologies. <P> Approach: In order to accomplish this overall objective, a series of simultaneous, coordinated research projects will be conducted under the five task sets, A through E. Task A: Biomolecular Recognition Elements: development of fluorescence-based electrochemical detection of biological interactions; Task B: Biomolecular Recognition Elements and Sensor Platform Development: development of rapid lateral flow test strips -- two types of strips will be developed. One is for the detection of methicillin resistant Staphylococcus aureus (MRSA) based on the utilization of the antibody newly developed at our center, the other is for anthrax spores based on the usage of phage developed by us. The antibody and phage will be conjugated with gold colloids to enhance the sensitivity of the strips; Task C: Biosensor Platform and System: development of magnetostrictive particle (MSP)-based sensor system for in-field tests -- handheld devices for interrogating magnetostrictive particle sensors will be built based on time domain and frequency domain technologies. The devices will be tested and characterized under different conditions in which a dynamic system will be employed. Based on the results, a procedure for conducting in-field detection of pathogens using magnetostrictive particle sensors will be established; Task D: Food Sample Preparation and Delivery: rapid sampling of pathogens from the surface of food. A methodology to rapidly collect the pathogens on the surface of tomatoes into a liquid will be developed. The pathogenic species in the liquid will be detected using biosensors. The percent recovery of the pathogens on the tomato surface will be determined; and Task E: In-field (in-situ) Detection of Pathogens: direct detection of pathogens on the surface of plants. The magnetostrictive particle sensors will be used to directly detect/monitor the pathogens on the plant surface. Sensors with different features, such as sensitivity and longevity, will be tested.