title: Rapid and alternative fabrication method for microfluidic paper based analytical devices.
abstract: A major application of microfluidic paper-based analytical devices (µPADs) includes the field of point-of-care (POC) diagnostics. It is important for POC diagnostics to possess properties such as ease-of-use and low cost. However, µPADs need multiple instruments and fabrication steps. In this study, two different chemicals (Hexamethyldisilazane and Tetra-ethylorthosilicate) were used, and three different methods (heating, plasma treatment, and microwave irradiation) were compared to develop µPADs. Additionally, an inkjet-printing technique was used for generating a hydrophilic channel and printing certain chemical agents on different regions of a modified filter paper. A rapid and effective fabrication method to develop µPADs within 10min was introduced using an inkjet-printing technique in conjunction with a microwave irradiation method. Environmental scanning electron microscope (ESEM) and x-ray photoelectron spectroscopy (XPS) were used for morphology characterization and determining the surface chemical compositions of the modified filter paper, respectively. Contact angle measurements were used to fulfill the hydrophobicity of the treated filter paper. The highest contact angle value (141°±1) was obtained using the microwave irradiation method over a period of 7min, when the filter paper was modified by TEOS. Furthermore, by using this method, the XPS results of TEOS-modified filter paper revealed Si2p (23%) and Si-O bounds (81.55%) indicating the presence of Si-O-Si bridges and Si(OEt) groups, respectively. The ESEM results revealed changes in the porous structures of the papers and decreases in the pore sizes. Washburn assay measurements tested the efficiency of the generated hydrophilic channels in which similar water penetration rates were observed in the TEOS-modified filter paper and unmodified (plain) filter paper. The validation of the developed µPADs was performed by utilizing the rapid urease test as a model test system. The detection limit of the developed µPADs was measured as 1unitml(-1) urease enzyme in detection zones within a period of 3min. The study findings suggested that a combination of microwave irradiation with inkjet-printing technique could improve the fabrication method of µPADs, enabling faster production of µPADs that are easy to use and cost-effective with long shelf lives.
authors.affiliation: Nanotechnology and Nanomedicine Division, Institute of Science, Hacettepe University, Ankara, Turkey.
authors.forename: Soheil
authors.initials: S
authors.lastname: Malekghasemi
authors.affiliation: Nanotechnology and Nanomedicine Division, Institute of Science, Hacettepe University, Ankara, Turkey; UNAM-National Nanotechnology Research Center, Bilkent University, Ankara 06800, Turkey.
authors.forename: Enver
authors.initials: E
authors.lastname: Kahveci
authors.affiliation: Nanotechnology and Nanomedicine Division, Institute of Science, Hacettepe University, Ankara, Turkey. Electronic address: memi@hacettepe.edu.tr.
authors.forename: Memed
authors.initials: M
authors.lastname: Duman
keywords: Cellulose fibers; Ink-jet printing; Microfluidic paper based analytical device; Microwave irradiation; Point of care; Silylation