Fenilketonüri Tanısı İçin Kağıt-Tabanlı Mikroakışkan Analitik Cihaz Geliştirilmesi
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Phenylketonuria (PKU), is a disease caused by the failure of phenylalanine metabolization and resulting accumulation at blood and other body fluids causing brain damage. Despite periodic phenylalanine monitoring is a necessity for PKU patients; due to being a time consuming test with high costs and requirement of analytical grade equipment along with trained personnel, it is not widely accessible especially at the rural areas where the disease is more common. Porous structure, precisely controllable surface properties and easy biological modification makes paper a commonly used material in biology, especially in sensor applications. One of the most widely used fabrication methods for preparation of paper based microfluidic systems is inkjet printing. This method enables fast and vast production of test systems with very high pattern resolution and repeatability with regant volumes as low as picoliters per test strip. The first stage of detection mechanism which is an enzymatic process, is the reaction between phenylalanine and phenylalanine dehydrogenase in the presence of NAD+. This reaction results with reduction of NAD+ to NADH. In the second stage, NADH is oxidized again by mPMS and produce formazan as end-product. Consequently the amount of produced formazan is a function of the input phenylalanine concentration. Significantly different color of formazan comparing all the input samples and by-products allow us to detect formazan quantity on test specimen therefor input phenylalanine concentration. Calculated limit of detection for ink-jet printer fabricated test system is 4.01 mg/dL. Colorimetric response time is calculated as 8 minutes while fabrication time is reduced to 5 minutes. By printer fabrication, the ability to control spraying ratio electronically enables us to control the reactant concentration resulting a better control over the linear range of test system which is 0-22 mg/dL. Same feature also drastically improve sensor-to-sensor repeatability. Within this study; a low cost and fast responsive test system with minimal fabrication requirement has been successfully developed which can identify monitor required phenylketonuria, mid-hyperalaninemia, mid-phenylketonuria and classic phenylketonuria with colorimetric technique with high trust rate.