PB0861 - Smartphone-based detection of platelet response to ADP in microcapillary strips

Background: The lack of platelet function testing for primary care prevents effective monitoring of patients on anti-platelet therapy and the ability to personalise therapy. To enable rapid platelet function analysis in a wider setting we have developed a microfluidic ‘dip-stick’ coupled with smart-phone imaging that allows rapid assessment of platelet activation by ADP, a pathway regularly targeted by anti-platelet drugs.

Aims: To develop a proof-of-principle, inexpensive, simple ‘dip-stick’ device to detect platelet activation via ADP at point of care.

Methods: Microcapillary Film (MCF) is manufactured from melt-extruded Teflon® FEP. It contains 10 parallel capillaries with a 200 μm diameter. Capillaries were coated internally with hydrophilic polymer (PVOH) or modified coating solution ‘Coating X’ and then ADP. Coated capillaries were dipped into whole citrated blood from healthy volunteers (n=5) for 30 seconds. Capillary rise was imaged with a smart-phone camera. Height of capillary rise was analysed in ImageJ.

Results: Capillaries coated with PVOH did not demonstrate an ADP concentration dependant reduction in capillary rise and showed high variability with an average intra-strip coefficient of variation (CV) of 24%, and an average inter-strip CV of 14%. Treatment of blood with cangrelor did not significantly impact capillary rise. However, capillaries coated with ‘Coating X’ demonstrated an ADP concentration dependant reduction in capillary rise and were reproducible; with an average intra-strip CV value below 7%, and an average inter-strip CV value below 4%. In strips loaded with ADP at 100uM, mean reduction of capillary rise was -10.8%, upon treatment of blood with cangrelor this decreased to 0.78% (p < 0.0005).

Conclusion(s): We have developed a rapid, reproducible, proof-of-concept ‘dip-stick’ platelet function analyser capable of measuring platelet response to ADP and the inhibitory action of cangrelor. This demonstrates the potential utility of this device as an assay that could be widely used at point-of-care, meeting the unmet need of on-treatment testing.