| Recently, paper has been increasingly recognized as a noteworthy substrate for the construction of microfluidic devices, with the combination of advantages of both the paper (eg. high-abundance, low-cost, biocompatibility, easy-to-use) and conventional microfluidics (eg. miniaturization, portability, low sample consumption). Since the term of "microfluidic paper-based analytical devices"(μPADs) was firstly proposed by Whitesides and co-workers in2007, it has been paid great attention due to the great potential applications in many fields such as clinical diagnosis, food quality control and environmental monitoring. The present work aims to develop a novel and simple method for the fabrication of microfuludic paper-based analytical devices and to study the possible applications of μPADs in various biochemical analyses. The thesis is composed of three chapters:In chapter1, the current progress of microfluidic paper-based analytical devices was reviewed. Firstly, several techniques for fabrication of μPADs were comprehensively summarized and various detection methods were described respectively. Secondly, the wide applications of μPADs in areas such as clinical diagnosis, food quality control and environmental monitoring were introduced in details. And lastly, a brief introduction of the application of plasma technology in the fabrication of microfluidic devices was made.In chapter2, a novel and simple method was developed for fabricating microfuludic paper-based analytical devices by means of coupling hydrophobic silane to fibers of paper followed by region-selectively plasma treatment. Filter paper was first hydrophobized via octadecyltrichlorosilane (OTS) silanization and then region-selectively plasma-treated via a mask with desired channel network. The plasma-exposed area of the paper was turned to be hydrophilic due to the degradation of hydrophobic OTS coupled to the paper’s cellulose fibers. Two types of hybrid polymethylmethacrylate (PMMA) and polydimethylsiloxane (PDMS) masks were developed to obtain well defined hydrophilic channel with the required depth. With the elastic PDMS piece adhered to the rigid PMMA piece, it excellently solved the problem of the expansion of hydrophilic channel caused by the leakage of plasma atmosphere in the gap between the mask and paper. The effect of plasma-treating time on hydrophilicity of paper was investigated. The water contact angle (WCAs) dramatically decreased from133.9±1.3°to0°with the prolonging of the plasma treating time from0s to30s. Meanwhile, the depth of wettable channel could also increase to nearly the thickness (180μm) of the paper after treated for30s. Attenuated total reflectance Fourier transformed infrared (ATR-FT-IR) spectrometer and X-ray photoelectron spectroscopy (XPS) were applied to characterize the surface chemistry of paper during silanization and plasma treatment, and the related mechanism was discussed.In chapter3, the developed paper-based microfluidic chips presented in chapter2were applied in two areas as follows:1) Determination of plasma glucose in whole blood. Plasma was separated from blood cells due to their different mobility in the channel on paper and then reacted with the substrates of Trinder’s reaction. The analytical results observed with the μPAD-based colorimetric assays agreed well with those determined by conventional glucose meter.2) Paper-based Isoelectric Focusing (IEF). The patterned paper was used as the supporting media for IEF to separate and concentrate protein samples according to their differences in isoelectric point (PI). Detailed studies on how variations in different parameters including the chip configuration, applied potential and ampholyte concentration affect the performance of IEF were performed, and multi-channel parallel analysis for IEF was achieved. |
PDF Full Text Request