Development of an instrument-free microfluidic biosensor for malaria diagnosis

Abstract

Many communities that risk contracting malaria do not have access to high quality microscope based diagnosis. Antibody based point-of-care diagnostics have substantially improved disease outcomes in these communities. Despite this success, it is not always possible to maintain the cold chain storage conditions required to stabilise antibody-based diagnostic tests. The high thermal stability of nucleic acids makes aptamer based point-of-care tests an attractive alternative. The lab-based Aptamer Tethered Enzyme Capture Assay (APTEC) was developed for the detection of malaria parasite P. falciparum. Since then using low-cost high precision 3D printing we rapidly prototyped an instrument-free portable 3D printed microfluidic biosensor, which showed equivalent sensitivity and specificity to antibody based diagnostics when tested with clinical samples. Micro-magnetic beads coated in aptamers are contained within the microfluidic biosensor. To improve these, we have decorated the beads in peptide amphiphiles (PAs) which self-assemble into a nanofiber mesh. We have also developed an aptamer containing DNA tetrahedron nanostructure that can be integrated into the PA nanomesh. We predict that the increased surface area provided by the nanomesh and aptamer presentation provided by the tetrahedron nanostructure will improve the capture capacity of each magnetic bead and consequently increase the sensitivity of our biosensor without sacrificing assay durability. We propose that our thermostable instrument-free biosensor addresses the diagnostic challenges faced in malaria endemic regions, and can potentially be modified with biomaterial nanostructures to have an increased sensitivity when used to detect for P. falciparum infections.