Promoting access to haemostasis testing in resource-scarce and emergency settings using paper-based lateral flow diagnostic screening assays for coagulation disorders

Saidykhan, Jerro

Abstract

Haemostatic disorders cause excessive bleeding and clotting and result in high morbidity and mortality worldwide, but especially in low-income areas which often lack suitable facilities and expertise for affordable diagnosis and treatment. Simple and low-cost haemostasis tests in such areas would permit diagnosis and effective treatment and thus reduce the associated morbidity and mortality. In a quest to provide simple, affordable, and yet effective haemostasis tests for low resource areas, this project utilised simple materials in the form of chromatography paper, coupled with inexpensive fabrication techniques such as wax printing and drop-casting to develop a number of low-cost and easy-to-use lateral flow devices for testing for haemostasis dysfunctions.
The devices developed in this project were all fabricated using the same basic techniques and procedures. Firstly, lateral flow test strip formats were designed using Microsoft PowerPoint and printed onto chromatography papers using wax printing. The printed papers were cured in an oven at 100oC for two minutes, allowing wax to sink to make a hydrophobic boundary. The strips were then modified with appropriate reagent(s) via drop-casting and allowed to air dry before being cut and inserted into test strip holders. The strip holders were fabricated using 3D printing and were equipped with elevated rails to ensure that samples only flowed through the paper, a millimetric graduation scale to measure the distances travelled by the samples, and an opening for sample deposition and the visual monitoring of sample flow.
In all, two paper-based lateral flow coagulation assay devices were developed, and the effect of platelet aggregation on sample flow was also investigated, and which were all based on the principle that coagulation or aggregation would alter the flow rate, or distance travelled by the sample. Assay development for each device began with isolating the effect of either coagulation or platelet adhesion/aggregation on sample flow rates from other contributions such as sample viscosity or reagent deposition. These coagulation or aggregation effects were then enhanced via optimising the relevant analytical parameters such as the type and amount of reagent immobilised on assay strips, sample volume, and strip geometry. Optimized formats of the devices were then calibrated and validated against routine reference methods using artificially constructed and clinical samples.
The first coagulation testing device was developed to measure fibrinogen concentration in blood plasma and provided results within five minutes. This device had good agreement with an established reference method for fibrinogen concentrations of 0.5 to 7.0 mg/mL. The second coagulation testing device was a prothrombin assay and measured the effect on clotting in distance rather than in time. The distance values form the device had a good correlation with prothrombin time (PT) values from a reference routine hospital method (r2=0.7209) for samples with PT values ≤40.0 s. The device for platelet aggregation on lateral flow strips could distinguish dysfunctional platelet samples from normal ones (p<0.05) based on the difference in their travel distances. In addition, it showed a strong correlation between platelet count and sample distance (r2=0.9928) and Aggregation Effect (r2=0.7846). This means it could also potentially test for quantitative platelet disorders.
In summary, two novel paper-based lateral flow coagulation testing devices have been developed. In addition, platelet aggregation and its effect on sample flow have been determined thus laying the foundation for development of a lateral flow platelet function analyser. These devices have the potential for deployment and incorporation into healthcare delivery systems in low-income areas to alleviate morbidity and mortality associated with bleeding and clotting disorders.

Citation

Saidykhan, J. Promoting access to haemostasis testing in resource-scarce and emergency settings using paper-based lateral flow diagnostic screening assays for coagulation disorders. (Thesis). University of the West of England. Retrieved from https://uwe-repository.worktribe.com/output/10774108

• Thesis Type: Thesis
• Deposit Date: May 10, 2023
• Publicly Available Date: Nov 17, 2023
• Public URL: https://uwe-repository.worktribe.com/output/10774108
• Award Date: Nov 17, 2023