A rapid and portable test for home monitoring of phenylalanine levels by patients with phenylketonuria using a blood glucose meter

项目摘要/摘要 苯丙酮尿症(PKU)是一种严重的先天性代谢紊乱，每15,000名新生儿中就有1名受到影响 每年在美国。PKU的特征效应是机体转换氨基酸的能力受损 苯丙氨酸(Phe)转化为酪氨酸，其结果是，血液中Phe水平升高。而Phe是必需的 对于正常的生长和大脑发育，过量的苯丙氨酸会导致大脑损伤，最终导致严重的智力障碍 减损。长期接触苯丙氨酸的影响在儿童时期和 怀孕，导致儿童生长迟缓和神经功能障碍，发育迟缓， 胎儿小头畸形和先天性心脏病。因此，PKU患者需要精心控制和治疗。 在他们的一生中监测他们的血液Phe水平，特别是对婴儿、儿童和孕妇。 为了控制血液中的Phe水平，一种特别设计的低Phe饮食，不含蛋白质的食物， 必须遵守。因为Phe饮食很难遵循，且长期暴露在Phe升高以及 血Phe的频繁波动影响正常生长和脑发育，血Phe水平是例行公事 监测PKU患者。然而，今天监测血液Phe需要很长的周转时间，因为 血液样本需要首先通过抽血或在滤卡上采集，然后在临床实验室进行分析 使用昂贵而精密的仪器。因此，许多PKU患者只能维持次佳的血液Phe 水平，即使是他们也愿意做出饮食调整。因此，家庭Phe监控提供了 为了获得更好的健康结果和避免神经认知问题，立即的测试结果是必不可少的。 虽然已经报道了在家庭中监测苯丙氨酸的方法，但大多数方法依赖于光学检测，即 易受临床样本中有色物种的干扰，或使用 复杂的分析方法或高度改进的电化学检测器，限制了它们的商业潜力。 基于这种迫切的需求和我们最近的发现，许多商业上可以获得的血糖 仪器(BGM)可以测量NADH的水平，这是许多酶分析中的辅助因素，我们建议改变用途 BGM被糖尿病患者广泛用于PKU患者监测血苯丙氨酸水平。我们已经开发出一种技术 这允许直接使用现有的葡萄糖试纸通过苯丙氨酸酶对苯丙氨酸进行定量 在苯丙氨酸存在下产生NADH的脱氢酶。此外，我们还开发了定制的 仪器，以提高NADH的灵敏度，同时仍使用现有的葡萄糖试纸。在这个第一阶段的项目中，我们将 重点是通过建立一种基于BGM的Phe分析方法，然后用传感器条来验证其可行性 发展。通过利用当今的BGM平台，我们可以大幅减少与以下各项相关的时间和成本 医疗器械研发和扩大生产，同时为北大提供易于使用和负担得起的解决方案 让患者在家中或在任何护理环境中快速监测他们的苯丙氨酸水平。

Project Summary/Abstract Phenylketonuria (PKU) is a serious inborn metabolic disorder affecting 1 out of every 15,000 children born in the U.S. annually. Characteristic effect of PKU is the impaired capability of the body to convert the amino acid phenylalanine (Phe) to tyrosine and, as a result, Phe level is elevated in the blood stream. While Phe is required for normal growth and brain development, excess Phe leads brain damage and ultimately severe intellectual impairment. The effects of prolonged exposure to Phe is much more pronounced during childhood and pregnancy, resulting in growth retardation and neurological impairment in children, development delay, microcephaly and congenital heart disease in fetuses. Therefore, patients with PKU need carefully control and monitoring of their blood Phe level for their whole lives, especially for infants, children and pregnant women. To control blood Phe levels, a specially designed low Phe diet, which is devoid of protein-containing food, must be followed. Since Phe diet are difficult to follow and prolonged exposure to elevated Phe as well as frequent fluctuation of blood Phe impacts normal growth and brain development, blood Phe levels are routinely monitored for patients with PKU. However, monitoring blood Phe today requires long turn-around time, since blood sample needs to be first collected via a blood drawn or on filter card, then analyzed in a clinical laboratory using costly and sophisticated instrument. Hence, many PKU patients can only maintain a suboptimal blood Phe levels, even they are willing to make dietary adjustment. Therefore, home Phe monitoring providing with immediate test result is imperative to achieve better health outcomes and to avoid neurocognitive issues. Although methods have been reported for monitoring Phe at home, most of them rely on optical detection that is vulnerable to interferences from colored species in clinical samples, or electrochemical detection that uses sophisticated assay methods or highly modified electrochemical detectors, limiting their commercial potentials. Based on this compelling need and our recent discovery that many commercially available Blood Glucose Meters (BGMs) can measure levels of NADH, a cofactor in many enzymatic assays, we propose to repurpose the BGM widely used by diabetics for PKU patients to monitor blood Phe levels. We have developed a technology that allows the direct use of existing glucose test strips for quantification of Phe, via an enzyme phenylalanine dehydrogenase that generates NADH in the presence of Phe. Furthermore, we have developed a customized meter to improve the NADH sensitivity while still using existing glucose test strips. In this Phase I project, we will focus on demonstrating the feasibility by developing a BGM based Phe assay followed by sensor strip development. By leveraging today’s BGM platform, we can drastically reduce the time and cost associated with medical device R&D and scale up production, while delivering an easy-to-use and affordable solution for PKU patients to monitor their Phe levels rapidly at home or at any point of care setting.