title: Single-Digit Pathogen and Attomolar Detection with the Naked Eye Using Liposome-Amplified Plasmonic Immunoassay.
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).
authors: Department of Bioproducts and Biosystems Engineering, University of Minnesota Twin Cities , St. Paul, Minnesota 55108-6005, United States.
authors: Minh-Phuong Ngoc
authors: MP
authors: Bui
authors: Department of Bioproducts and Biosystems Engineering, University of Minnesota Twin Cities , St. Paul, Minnesota 55108-6005, United States.
authors: Snober
authors: S
authors: Ahmed
authors: Department of Bioproducts and Biosystems Engineering, University of Minnesota Twin Cities , St. Paul, Minnesota 55108-6005, United States.
authors: Abdennour
authors: A
authors: Abbas
mesh_terms: D000818:Animals; D003124:Colorimetry / Q000379:methods; D004797:Enzyme-Linked Immunosorbent Assay; D004927:Escherichia coli Infections / Q000382:microbiology; D019453:Escherichia coli O157 / Q000302:isolation & purification*; D005516:Food Microbiology; D006046:Gold / Q000737:chemistry*; D006801:Humans; D007118:Immunoassay / Q000379:methods*; D008081:Liposomes / Q000737:chemistry* / Q000648:ultrastructure; D008087:Listeria / Q000302:isolation & purification*; D053768:Metal Nanoparticles / Q000737:chemistry* / Q000648:ultrastructure; D011817:Rabbits; D012475:Salmonella / Q000302:isolation & purification*; D012480:Salmonella Infections / Q000382:microbiology; D014871:Water Microbiology
chemical_list: D008081:Liposomes; D006046:Gold
keywords: Plasmonic colorimetry; foodborne pathogens; gold nanoparticles; immunoassay; liposomes; signal amplification