PB0860 - Smartphone-based detection of the coagulation cascade and/or platelet activation in ‘dip-stick’ microcapillary strips

Background: The lack of platelet function testing suitable for primary care prevents the use of platelets as biomarkers and/or for monitoring anti-platelet therapy. To enable rapid haemostatic analysis in wider settings, we have adapted microfluidic technology with smart-phone imaging to develop a ‘dip-stick’ haemostatic function analyser.

Aims: To develop a proof-of-principle, inexpensive, simple ‘dip-stick’ device to detect coagulation/platelet activation.

Methods: Microcapillary Film (MCF) is manufactured from melt-extruded Teflon® FEP. It contains 10 parallel capillaries with a mean 200 μm diameter. Capillaries were coated internally with a hydrophilic polymer (PVOH) and then thrombin. Coated capillaries were dipped into whole citrated blood from healthy volunteers (n=6) for 30 seconds. Capillary rise was imaged with a smart-phone camera. Height of capillary rise was analysed in ImageJ.

Results: Capillaries coated with thrombin showed a concentration dependant reduction in capillary rise, with an average intra-strip coefficient of variation (CV) < 6%, and an average inter-strip CV < 3%. In strips loaded with 50 units/ml thrombin, mean capillary rise was 24.1% lower than control (p < 0.0005). Pre-treatment of blood with hirudin to inhibit thrombin completely reversed this effect; capillary rise reduced by 0.37% compared to control (p>0.05). Pre-treatment of blood with the peptide GPRP, which allowed platelet activation but inhibited clot formation partially reversed thrombin’s effect on capillary rise, reducing by 6.1% relative to control (p < 0.05), but 18.0% higher than thrombin alone (p < 0.0005). We also showed that haematocrit correlated with rise in agonist-free capillaries yet reduction in rise due to thrombin was independent of blood cells counts.

Conclusion(s): We have developed a reproducible proof-of-principle ‘dip-stick’ haemostatic function analyser with the capability of measuring coagulation/platelet function, independently or in combination. This demonstrates the potential utility of this device as an assay that could be used point-of-care and in large scale platelet function studies, meeting important medical and research needs.