1. Single-Digit Pathogen and Attomolar Detection with the Naked Eye Using Liposome-Amplified Plasmonic Immunoassay
- Author
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Minh Phuong Ngoc Bui, Snober Ahmed, and Abdennour Abbas
- Subjects
Listeria ,Metal Nanoparticles ,Bioengineering ,Enzyme-Linked Immunosorbent Assay ,Escherichia coli O157 ,Salmonella ,medicine ,Animals ,Humans ,General Materials Science ,Colorimetry ,Pathogen ,Plasmon ,Escherichia coli Infections ,Immunoassay ,Liposome ,medicine.diagnostic_test ,Chemistry ,Mechanical Engineering ,General Chemistry ,Condensed Matter Physics ,Molecular biology ,Orders of magnitude (mass) ,Colloidal gold ,Liposomes ,Salmonella Infections ,Food Microbiology ,Naked eye ,Gold ,Rabbits ,Water Microbiology - 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).
- Published
- 2015