Novel planar and particle-based microarrays for point-of-care diagnostics

Sammanfattning: Point-of-care assays are easy-to-use, portable and inexpensive tests that canbe used to aid diagnostics by measuring levels of disease-specific moleculesin settings where access to advanced laboratory equipment and trainedpersonnel are limited, such as at the patient's bedside or in low resourceparts of developing countries. In order to achieve high multiplexingcapacities, such assays can be based on planar microarrays consisting ofspots immobilized on a flat surface or on particle-based microarrays basedon populations of encoded particles. The aim of the work presented in thisthesis is to develop new point-of-care amenable planar and particle-basedmicroarrays that allow for highly multiplexed assays while maintaining lowsample-to-result times, complexity and instrumentation requirements.Paper I demonstrates the use graphically encoded particles for colorimetricdetection of autoantibodies using a consumer-grade flatbed scanner. Fourgraphical characters on the surface of each particle allows for millions ofcodes and the use of gold nanoparticles as a detection label allows both thecode and the signal intensity to be read out in a single image.Paper II describes a signal enhancement method that increases thesensitivity of gold nanoparticle detection on planar microarrays. Using thismethod, detection of allergen-specific IgE can be carried out using aconsumer-grade flatbed scanner instead of a more expensive fluorescencescanner without sacrificing assay performance.Paper III demonstrates the use of an isothermal DNA amplification methodfor detection of adenoviral DNA on a paper-based microarray. Using anisothermal amplification method eliminates the need for a thermocycler,reducing the instrumentation required for such detection.Paper IV shows the use of solid-phase PCR to amplify bacterial DNA directlyon the surface of particles. This strategy reduces assay time by eliminatingthe need for separate amplification and hybridisation steps.