(H-296) SicklED: Affordable, Point-of-Care, Sickle Cell Anemia Lateral Flow Screening Device

Introduction:: Sickle Cell Disease (SCD) is a genetic blood disorder prevalent in many regions around the world, especially in sub-Saharan Africa. Developed, high income countries have better access to advanced resources, such as isoelectric focusing, to diagnose and treat individuals with the disease to prevent mortality. Low to middle income countries (LMICs) lack the same accessibility due to the high expenses, resulting in a large amount of the population undiagnosed and untreated. To address the high prevalence of SCD in LMICs, the team has developed an affordable, point-of-care lateral flow screening device that is able to test if an individual has SCD, carries the trait or is healthy. Within the next 3 to 8 years, the team plans to finish optimizing the device to allow for widespread implementation in Sierra Leone and eventually other countries as standard neonatal screening procedure in order to lower the high mortality rate due to SCD.


Materials and Methods:: The device utilizes an E-shaped geometry to reduce the hook effect, where the oversaturation of capture antibodies by the antigen inhibits the test line from forming and therefore, providing inaccurate diagnoses. Our test strip is composed of three components: nitrocellulose membrane with adhesive polystyrene backing card, CF5 absorbance pad, and conjugate release pad. To detect HbA and HbS specifically, antibodies from various companies have been experimented with in different combinations as capture or detection antibodies to identify specific antibodies that maximize the test line intensities. When running the test strip, a sample of purified hemoglobin-HbA is deposited onto the device, followed with a wash buffer, and lastly, the anti-HbA blue conjugated beads. When the reagents interact with the antibody test lines, a blue dot will appear to signify the diagnosis. The team utilizes ImageJ software to quantify the test line intensitive from the experiments to optimize accurate diagnoses.


Results, Conclusions, and Discussions:: As shown in Figure A, a successful prototype has been developed and validated through its ability to bind antigens within the blood sample to their respective antibodies spotted on the test strip and conjugated beads to allow test lines to appear. It is able to detect both anti-HbA and anti-HbS through numerous experiments. The control test line also confirms the functionality of the test strip. Through optimizing the device geometry and wash buffer recipe, the test strips show specific binding to the target antigens even at a high antigen concentration of 20 mg/mL. Figure 2B shows the values received from ImageJ software to determine standard quality control value for received test results. Overall, the produced results are accurate even though the small amount of cross reaction seen can be lessened and optimized.


The team’s current efforts have been to improve the sensitivity and specificity of the device and determine the dynamic range and highest efficient buffer to reduce cross reactivity and allow test lines with the highest intensity to appear. Our device proves to be functional through the various experiments tested on it and through further optimization on sensitivity and specificity, our device can become accurate enough to be implemented as SOP in Sierra Leone. The team is also initiating manufacturing and implementation models. The team will be able to test the device in SL in the summer of 2023 to understand how the device works with real patient blood samples to better optimize and improve its functionality.




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