A.E. Saunders, R.K. Baldwin, S.J. Oldenburg
Fortis Life Sciences,
Keywords: nanoparticles, lateral flow assay, organ injury, biomarkers, magnetic separation
Summary:Organ injury – arising from diverse causes such as heart attack, chemical exposure, and other factors – induces biochemical changes in the human body that can be directly measured. The ability to detect and quantify relevant biomarkers associated with organ damage without the need for blood collection would be of tremendous benefit when such events occur outside of a clinical setting. Saliva-based lateral flow diagnostics are attractive due to low cost, rapid results, and the low-invasive nature of specimen collection, but developing such tests faces challenges associated with both biomarker prevalence – relevant markers in saliva can be 1000-fold less concentrated than they are in blood – and there may be high concentrations of dissolved solids, such as mucins, which interfere with the controlled flow required for assays based on capillary draw. Here we present results describing the development of lateral flow assays for the detection of biomarkers associated with organ damage in which these challenges are addressed through control over on-strip chemistry to address flow characteristics, the development of novel magnetic-plasmonic reporter particles to allow sample concentration and enhanced assay sensitivity, and customized housings to enable magnet-based control over reporter particle introduction to the assay. At nanoComposix, we have developed a class of magnetic reporter particles that allows us to reach the necessary assay sensitivity levels despite the low biomarker concentrations in saliva. This increase in sensitivity is partly driven by the development of custom reporter particles – the coating of a gold shell onto the surface of a magnetically responsive core allows for the magnetic isolation of the particles after binding the analyte, effectively generating more concentrated samples to measure while the gold shell provides an enhanced optical signal compared to solid gold particles. To incorporate these particles most effectively into a familiar lateral assay format, a magnetic concentration device integrated into the cassette housing was developed to allow for simple on-strip magnetic concentration prior to running the assay. Results are presented for an assay developed to detect the presence of a biomarker associated with cardiac injury (Troponin I) with discussion for extension of this approach to other organ injury biomarkers of interest.