Department of Biomedical Engineering, University of Houston, 3605 Cullen Blvd, Houston, TX 77204-5060, USA.
Department of Pediatrics, Section of Hematology-Oncology, Baylor College of Medicine, Houston, TX 77030, USA.
Biosensors (Basel). 2017 Sep 20;7(3):39. doi: 10.3390/bios7030039.
Sickle cell anemia (SCA) is a genetic blood disorder that is particularly lethal in early childhood. Universal newborn screening programs and subsequent early treatment are known to drastically reduce under-five SCA mortality. However, in resource-limited settings, cost and infrastructure constraints limit the effectiveness of laboratory-based SCA screening programs. To address this limitation our laboratory previously developed a low-cost, equipment-free, point-of-care, paper-based SCA test. Here, we improved the stability and performance of the test by replacing sodium hydrosulfite (HS), a key reducing agent in the hemoglobin solubility buffer which is not stable in aqueous solutions, with sodium metabisulfite (MS). The MS formulation of the test was compared to the HS formulation in a laboratory setting by inexperienced users ( = 3), to determine visual limit of detection (LOD), readout time, diagnostic accuracy, intra- and inter-observer agreement, and shelf life. The MS test was found to have a 10% sickle hemoglobin LOD, 21-min readout time, 97.3% sensitivity and 99.5% specificity for SCA, almost perfect intra- and inter-observer agreement, at least 24 weeks of shelf stability at room temperature, and could be packaged into a self-contained, distributable test kits comprised of off-the-shelf disposable components and food-grade reagents with a total cost of only $0.21 (USD).
镰状细胞贫血症（SCA）是一种遗传性血液疾病，在儿童早期尤其致命。众所周知，普遍的新生儿筛查计划和随后的早期治疗可以大大降低五岁以下 SCA 的死亡率。然而，在资源有限的环境中，成本和基础设施的限制限制了基于实验室的 SCA 筛查计划的有效性。为了解决这一限制，我们的实验室之前开发了一种低成本、无设备、即时、基于纸张的 SCA 测试。在这里，我们通过用不稳定的水溶液中的血红蛋白溶解度缓冲剂中的关键还原剂亚硫酸氢钠（HS）替换偏亚硫酸钠（MS），提高了测试的稳定性和性能。该测试的 MS 配方在实验室环境中与 HS 配方进行了比较，由无经验的用户（n = 3）进行，以确定目视检测限（LOD）、读数时间、诊断准确性、观察者内和观察者间一致性以及保质期。MS 测试的镰状血红蛋白 LOD 为 10%，读数时间为 21 分钟，SCA 的灵敏度为 97.3%，特异性为 99.5%，观察者内和观察者间一致性几乎完美，在室温下至少 24 周的货架稳定性，并且可以包装成一个独立的、可分发的测试套件，由现成的一次性组件和食品级试剂组成，总成本仅为 0.21 美元（USD）。
