title: Microretroreflector-sedimentation immunoassays for pathogen detection.
abstract: Point-of-care detection of pathogens is medically valuable but poses challenging trade-offs between instrument complexity and clinical and analytical sensitivity. Here we introduce a diagnostic platform utilizing lithographically fabricated micron-scale forms of cubic retroreflectors, arguably one of the most optically detectable human artifacts, as reporter labels for use in sensitive immunoassays. We demonstrate the applicability of this novel optical label in a simple assay format in which retroreflector cubes are first mixed with the sample. The cubes are then allowed to settle onto an immuno-capture surface, followed by inversion for gravity-driven removal of nonspecifically bound cubes. Cubes bridged to the capture surface by the analyte are detected using inexpensive, low-numerical aperture optics. For model bacterial and viral pathogens, sensitivity in 10% human serum was found to be 10(4) bacterial cells/mL and 10(4) virus particles/mL, consistent with clinical utility.
authors.affiliation: Department of Chemical and Biomolecular Engineering, †Materials Engineering Program, ‡Department of Electrical and Computer Engineering, ⊥Department of Biology and Biochemistry, University of Houston , 4800 Calhoun Road, Houston, Texas 77004, United States.
authors.forename: Gavin
authors.initials: G
authors.lastname: Garvey
authors.forename: David
authors.initials: D
authors.lastname: Shakarisaz
authors.forename: Federico
authors.initials: F
authors.lastname: Ruiz-Ruiz
authors.forename: Anna E V
authors.initials: AE
authors.lastname: Hagström
authors.forename: Balakrishnan
authors.initials: B
authors.lastname: Raja
authors.forename: Carmen
authors.initials: C
authors.lastname: Pascente
authors.forename: Archana
authors.initials: A
authors.lastname: Kar
authors.forename: Katerina
authors.initials: K
authors.lastname: Kourentzi
authors.forename: Marco
authors.initials: M
authors.lastname: Rito-Palomares
authors.forename: Paul
authors.initials: P
authors.lastname: Ruchhoeft
authors.forename: Richard C
authors.initials: RC
authors.lastname: Willson
mesh_terms: D055910:Antibodies, Immobilized / Q000737:chemistry / Q000276:immunology; D001419:Bacteria / Q000276:immunology / Q000302:isolation & purification*; D004926:Escherichia coli / Q000276:immunology / Q000302:isolation & purification; D006801:Humans; D007118:Immunoassay; D017909:Levivirus / Q000276:immunology / Q000302:isolation & purification; D008828:Microbiological Techniques / Q000379:methods*; D019095:Point-of-Care Systems; D011126:Polypropylenes / Q000737:chemistry; D014780:Viruses / Q000276:immunology / Q000302:isolation & purification*
chemical_list: D055910:Antibodies, Immobilized; D011126:Polypropylenes