Kağıt-Tabanlı Biyosensör Tasarımı ve Geliştirilmesi

Abstract

In the last few years biosensors have been used broadly in diagnostics, especially in application of point-of-care (POC). POC diagnostics required to be easy-to-use and affordable. Microfluidic paper-based analytical devices (µPADs) have been one of the POC diagnostic devices. In order to fabricate µPADs are developed variety of methods such as photolithography, plotting, plasma etching, screen printing, flexographic printing, wax and ink-jet printing. Inkjet printing technique has become one of the most promising and versatile techniques. The obvious advantages of this technique are reproducibility, printing multiple pages rapidly, inexpensive and ability to work with very small volumes of ink (picolitres). In this thesis, we presented a novel fabrication method for development of paper-based microfluidic device by using inkjet printing technique. Special positive features of this method are low number of process steps (one step), cost-effectiveness and reaching result at the lowest time span (~10 min). In this method, we used and compare two different silylating agents Tetraethylorthosilicate (TEOS) and Hexamethyldisilazane (HMDS) to create hydrophobic barriers on the filter paper. The silylation was achieved by using three different methods including heating, plasma treatment and microwave irradiation. In order to generate hydrophilic channels on modified paper, HCl etching approach was used by ink-jet printer. Also, urea solution and phenol red were printed into own zones as reactive material and indicator reagent, respectively. Surface chemical analysis of samples was carried out by using of X-ray Photoelectron Spectroscopy (XPS). Morphology of treated filter papers was obtained by Environmental Scanning Electron Microscope (ESEM). Washburn assay was performed to study the performance of penetration behavior of generated hydrophilic channels. Also, the wettability of treated paper surface was measure by using contact angle instrument at room temperature as well. This lab-on-a-paper (LOP) biosensor could be kept in room temperature for a year. The validation test of our µPADs was performed successfully with determination of urease enzyme without "coffee ring effect" in detection zones. Thus, the inkjet printer provides the least fabrication steps and produces biosensors will be simple-to-use, cost-effective and have long shelf life and fabricated fast.