Susana Diaz-Amaya1 Li-Kai Lin1 Amanda Deering2 Lia Stanciu1

1, School of Materials Engineering, Neil Armstrong Hall of Engineering, Purdue University, West Lafayette, Indiana, United States
2, Department of Food Science, Philip E. Nelson Hall of Food Science, Purdue University, West Lafayette, Indiana, United States

Infectious outbreaks caused by foodborne pathogens such as E. coli O157:H7 are still occurring worldwide and cause acute illnesses and significant industrial impact. As a chemical component of organic materials, bisphenol A (BPA) is used in the food and consumer products industries. Despite its benefits, low-dose exposure to BPA adversely affects human health because it is an endocrine disrupting chemical (EDC).
We present on the feasibility of using aptameric DNA sequences, covalently conjugated to colloidal nanoparticles, for the sensitive and highly specific detection of whole cell pathogens and small molecule toxic molecules via surface enhanced Raman spectroscopy (SERS) analysis.
Low concentrations of E. coli O157:H7 were detected (~101 CFU/mL) and quantified (~102 CFU/mL) within 20 minutes in both pure culture and ground beef samples. We also report on a new range-extended bisphenol A (BPA) detection method that includes high-SERS-performance gold nanoparticles, i.e., 40 nm gold nanostars (GNSs) and 4-aminothiolphenol (4-ATP) as Raman reporters. The limit of detection for BPA was 0.073 ppb, which is 205 and 20 times more sensitive
than those of visual intensity and color intensity quantifications, respectively.