Single-Digit Pathogen and Attomolar Detection with the Naked Eye Using Liposome-Amplified Plasmonic Immunoassay

Minh Phuong Ngoc Bui, Snober Ahmed, Abdennour Abbas

Research output: Contribution to journalArticlepeer-review

91 Scopus citations

Abstract

We introduce an enzyme-free plasmonic immunoassay with a binary (all-or-none) response. The presence of a single pathogen in the sample results in a chemical cascade reaction leading to a large red to dark-blue colorimetric shift visible to the naked eye. The immediate and amplified response is initiated by a triggered breakdown of cysteine-loaded nanoliposomes and subsequent aggregation of plasmonic gold nanoparticles. Our approach enabled visual detection of a single-digit live pathogen of Salmonella, Listeria, and E. coli O157 in water and food samples. Furthermore, the assay allowed a naked-eye detection of target antibody concentrations as low as 6.7 attomolar (600 molecules in 150 μL); six orders of magnitude lower than conventional enzyme-linked immunosorbent assay (ELISA).

Original languageEnglish (US)
Pages (from-to)6239-6246
Number of pages8
JournalNano letters
Volume15
Issue number9
DOIs
StatePublished - Sep 9 2015

Keywords

  • Plasmonic colorimetry
  • foodborne pathogens
  • gold nanoparticles
  • immunoassay
  • liposomes
  • signal amplification

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