Fluorescence microscopy has long been a standard tool in laboratory medicine. Implementation of fluorescence microscopy for near-patient diagnostics, however, has been limited due to cost and complexity associated with traditional fluorescence microscopy techniques. There is a particular need for robust, low-cost imaging in high disease burden areas in the developing world, where access to central laboratory facilities and trained staff is limited. Here we
describe a point-of-care assay that combines a disposable plastic cartridge with an extremely low cost fluorescence
imaging instrument. Based on a novel, multi-mode planar waveguide configuration, the system capitalizes on advances
in volume-manufactured consumer electronic components to deliver an imaging system with minimal moving parts and
low power requirements. A two-color cell imager is presented, with magnification optimized for enumeration of
immunostained human T cells. To demonstrate the system, peripheral blood mononuclear cells were stained with
fluorescently labeled anti-human-CD4 and anti-human-CD3 antibodies. Registered images were used to generate
fractional CD4+ and CD3+ staining and enumeration results that show excellent correlation with flow cytometry. The
cell imager is under development as a very low cost CD4+ T cell counter for HIV disease management in limited resource settings.
Cost-effective disease diagnosis in resource-limited settings remains a critical global health challenge. Qualitative rapid
tests based on lateral flow technology provide valuable screening information, but require relatively expensive
confirmatory tests and generally lack quantitation. We report on a fluorescence technology that combines low cost
instrumented readout with passive pumping in a disposable cartridge. The detection system utilizes a novel waveguide
illumination approach in conjunction with commercial CMOS imagers. Total instrument cost in production are
projected to be around $100 This cost structure and instrument ease of use will enable use in point-of-care settings,
outside of centralized laboratories. The system has been used for detection and analysis of proteins, antibodies, nucleic
acids, and cells. Here we will report first on our development of a multiplexed, array-based serology assay for HIV and
common AIDS co-infections. Data will be presented for HIV/HCV antibody testing in human serum samples. In
addition, we will present data on the use of the system for sensitive detection of bacterial RNA. Current detection limit
for the model multiplexed RNA sandwich assay is 1 femtomolar target RNA. Finally, a high magnification version of
the system is used to image immunostained human T cells.
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