2007 Annual Report 1a.Objectives (from AD-416) The goal of the proposed project is to develop an optical biosensor, based on innovative nanoparticle bioseparator and quantum dots biolabels, for detection of L. monocytogenes in food products including poultry, meat and vegetables. It is expected that the proposed biosensor will be able to detect one cell of viable L. monocytogenes in food samples in less than two hours. 1b.Approach (from AD-416) 1. Develop a novel nanoparticle bioseparator by coupling magnetic nanoparticles with anti-Listeria antibodies for high-efficiency separation of target pathogens from food matrix. 2. Develop novel nanoparticle biolabels by coupling semiconductor quantum dots (QDs) with anti-L. monocytogenes antibodies for very sensitive labeling of target pathogens with fluorescence. 3. Integrating the nanoparticle bioseparator, QDs biolabels, and fluorescent detector into a biosensing system for rapid screening of L. monocytogenes in foods. 3.Progress Report This report serves to document the research funded by The National Association for Food Safety and Security (NAFSS), "Nanoparticle-based Fluorescent Biosensor for Rapid Detection of Listeria monocytogenes in Foods," granted to Y. Li, University of Arkansas (principal investigator); L. Berghman, Texas A&M University; D. Fung, Kansas State University, J. Marcy, University of Arkansas, and S.-I. Tu, ARS collaborator (Specific Cooperative Agreement 58-1935-6-633). This agreement contributes to Milestones of Objectives 1 & 2 of CRIS 1935-42000-058-00D. This project is aligned to NP-108, Food Safety, Action Plan Component 1.2.1 and addresses ARS Strategic Plan Performance Measure 3.1.2. To ensure food safety and to minimize food product recalls associated with microbial hazards, rapid methods are needed to detect harmful bacteria (pathogens) in foods on-line or in real time. Listeria monocytogenes is a deadly foodborne pathogen, and immunoassays used for its detection are limited by their long detection time, low sensitivity, qualitative-only results and high cost. The objectives of this project are to develop a fluorescent biosensor for rapid detection of L. monocytogenes and to evaluate the biosensor with different foods. The biosensor system will consist of a new rapid growth medium, a novel nanobeads bioseparator, fluorescent quantum dots biolabels, and a fluorescent detector. A rapid growth medium for Listeria is being investigated for incubating samples to obtain detectable signal from a single cell of L. monocytogenes in less than 2 hours. To deal with complex food samples, a novel nanoparticle bioseparator was developed by coupling magnetic nanoparticles with anti-Listeria antibodies for high-efficiency separation and concentration of L. monocytogenes from food matrices. Antibodies that bind to L. monocytogenes were also linked to a fluorescent reporter (quantum dots) to develop nanoparticle biolabels for selective and sensitive detection of L. monocytogenes. The primary data showed that this biosensing method was able to quantitatively detect Listeira monocytogenes as low as several cells per mL in chicken and beef samples. The new growth medium, nanoparticle bioseparator, quantum dots biolabels, and a detector will be integrated into a biosensing system for rapid detection of L. monocytogenes in food samples. Progress has been monitored ADODR by e-mail correspondence and regular contact via phone.