Microretroreflector-sedimentation immunoassays for pathogen detection

Gavin Garvey, David Shakarisaz, Federico Ruiz-Ruiz, Anna E.V. Hagström, Balakrishnan Raja, Carmen Pascente, Archana Kar, Katerina Kourentzi, Marco Rito-Palomares, Paul Ruchhoeft, Richard C. Willson

Research output: Contribution to journalArticlepeer-review

10 Scopus citations


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 104 bacterial cells/mL and 104 virus particles/mL, consistent with clinical utility.

Original languageEnglish (US)
Pages (from-to)9029-9035
Number of pages7
JournalAnalytical Chemistry
Issue number18
StatePublished - Sep 1 2014

ASJC Scopus subject areas

  • Analytical Chemistry


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