Annual Report - Center for Food Safety Engineering - Purdue ...

BhuniaOptical biosensors for food pathogen detectionInvestigator: Arun Bhunia (Department of Food Science)Project RationaleThe ability of biosensors to detect the presence of pathogensor toxins is critical to ensure product safety. Biosensorsemploying specifi c antibodies are being widely used andshown to be effective. Our goal was to develop a fi ber opticsensor using antibodies for detecting foodborne pathogens,including Listeria monocytogenes, Escherichia coli O157:H7,and Salmonella Enteritidis. We developed a fi ber optic sensorfor L. monocytogenes and E. coli O157:H7. We also developeda sensitive and specifi c fi ber optic detection assay for S.Enteritidis in poultry. The assay was compared to time-resolvedimmunofl uorescence (TRF) for confi rmation. An effi cient multipathogenarray using a fl ow-through immobilization protocol wasalso developed for detecting L. monocytogenes, E .coli, and S.Enteritidis. Pilot studies are underway to analyze the bindingeffi ciencies of an antibody-pathogen complex using selectedsurface chemistries in order to gain a better understanding of themolecular nature of these interactions. This approach will enableus to increase sensitivity and specifi city of binding on the sensor.Project HighlightsWe obtained the antibodies required to detect multiple pathogensusing a fi ber optic sensor. The antibodies were labeled withfl uorophor (Alexa-Fluor) and thoroughly characterized accordingto their reaction patterns to target pathogens when grown on amulti-pathogen selective enrichment broth, SEL (Salmonella,E. coli, and Listeria). Initial experimental trials indicate that wecan detect these three pathogens simultaneously using a fi beroptic sensor. Cross-reactions with heterologous bacteria wereminimal.Project Objectives• Develop and evaluate an antibody-coupled fi ber opticbiosensor [ANALYTE 2000] for detecting S. Enteritidis.• Develop an effi cient multi-pathogen array using a fi beroptic biosensor. This requires screening and identifyingmonoclonal and polyclonal antibodies, developed inour laboratory, for L. monocytogenes, E. coli O157:H7,and S. Enteritidis, and developing effi cient surfacechemistry protocols for evaluating and quantifyingthe binding interactions of an antibody-pathogencomplex on the surface of a fi ber optic sensor.4Center for Food Safety Engineering“The ability of biosensors to detect the presence of pathogensor toxins is critical to ensure product safety.”