Biofunctionalized magnetic nanoparticle integrated mid-infrared pathogen sensor for food matrixes

Sandeep P. Ravindranath, Lisa J. Mauer, Chitrita Deb-Roy, Joseph Irudayaraj

Research output: Contribution to journalArticlepeer-review

126 Scopus citations


Magnetic nanoparticles functionalized with anti-Escherichia coliO157:H7 or anti-Salmonella typhimuriumantibodies that can specifically bind to their target organisms were used to isolate E. coliO157:H7 and S. typhimurium separately from a cocktail of bacteria and from food matrixes. The pathogens were then detected using labelfree 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. coliO157: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 speciesspecific antibodies with an in-built sample extraction step and could be applied in the field for on-site foodborne pathogen monitoring.

Original languageEnglish (US)
Pages (from-to)2840-2846
Number of pages7
JournalAnalytical Chemistry
Issue number8
StatePublished - Apr 15 2009

All Science Journal Classification (ASJC) codes

  • Analytical Chemistry


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