Point-of-care assays are easy-to-use, portable and inexpensive tests that can

be used to aid diagnostics by measuring levels of disease-specific molecules

in settings where access to advanced laboratory equipment and trained

personnel are limited, such as at the patient's bedside or in low resource

parts of developing countries. In order to achieve high multiplexing

capacities, such assays can be based on planar microarrays consisting of

spots immobilized on a flat surface or on particle-based microarrays based

on populations of encoded particles. The aim of the work presented in this

thesis is to develop new point-of-care amenable planar and particle-based

microarrays that allow for highly multiplexed assays while maintaining low

sample-to-result times, complexity and instrumentation requirements.

Paper I demonstrates the use graphically encoded particles for colorimetric

detection of autoantibodies using a consumer-grade flatbed scanner. Four

graphical characters on the surface of each particle allows for millions of

codes and the use of gold nanoparticles as a detection label allows both the

code and the signal intensity to be read out in a single image.

Paper II describes a signal enhancement method that increases the

sensitivity of gold nanoparticle detection on planar microarrays. Using this

method, detection of allergen-specific IgE can be carried out using a

consumer-grade flatbed scanner instead of a more expensive fluorescence

scanner without sacrificing assay performance.

Paper III demonstrates the use of an isothermal DNA amplification method

for detection of adenoviral DNA on a paper-based microarray. Using an

isothermal 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 directly

on the surface of particles. This strategy reduces assay time by eliminating

the need for separate amplification and hybridisation steps.