title: Biofunctionalized magnetic nanoparticle integrated mid-infrared pathogen sensor for food matrixes.
abstract: Magnetic nanoparticles functionalized with anti-Escherichia coli O157:H7 or anti-Salmonella typhimurium antibodies that can specifically bind to their target organisms were used to isolate E. coli O157:H7 and S. typhimurium separately from a cocktail of bacteria and from food matrixes. The pathogens were then detected using label-free IR fingerprinting. The binding and detection protocol was first validated using a benchtop FT-IR spectrometer and then applied to a portable mid-IR spectrometer to enable this approach as a point-of-detection technology. Highly selective detection was achieved in less than 30 min at both species (E. coli O157:H7 vs S. typhimurium ) and strain (E. coli O157:H7 vs E. coli K12) levels in complex food matrixes (2% milk, spinach extract) with a detection limit of 10(4)-10(5) CFU/mL. The combined approach of functionalized magnetic nanoparticles and IR spectroscopy imparts specificity through spectroscopic fingerprinting and selectivity through species-specific antibodies with an in-built sample extraction step and could be applied in the field for on-site food-borne pathogen monitoring.
authors.affiliation: Department of Agricultural and Biological Engineering and Bindley Bioscience Center, Purdue University, 225 South University Street, West Lafayette, Indiana 47907, USA.
authors.forename: Sandeep P
authors.initials: SP
authors.lastname: Ravindranath
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Mauer
authors.forename: Chitrita
authors.initials: C
authors.lastname: Deb-Roy
authors.forename: Joseph
authors.initials: J
authors.lastname: Irudayaraj
mesh_terms: D000906:Antibodies / Q000737:chemistry / Q000276:immunology; D015374:Biosensing Techniques / Q000379:methods*; D019453:Escherichia coli O157 / Q000276:immunology / Q000302:isolation & purification; D005504:Food Analysis / Q000379:methods*; D005516:Food Microbiology; D008280:Magnetics; D053758:Nanoparticles / Q000737:chemistry*; D015203:Reproducibility of Results; D012680:Sensitivity and Specificity; D013055:Spectrophotometry, Infrared
chemical_list: D000906:Antibodies