| In this dissertation, two applications of microfluidic paper-based analytical devices (μPADs) as potential point-of-care (POC) devices were demonstrated. With their inexpensive fabrication, reduced reagent and sample volumes, compatibility with image analysis techniques, and usability outside of conventional laboratories, the μPADs provide a unique platform for performing a wide variety of bioassays. The first application is for the development of a paper-based enzyme-linked immunosorbent assay (P-ELISA) for the detection of a human performance biomarker, Neuropeptide Y (NPY). After optimizing the P-ELISA detection of rabbit IgG through the use of a novel combination of colorimetric image analysis and efficient enzyme---substrate systems, limits of detection were improved four orders of magnitude over previously reported values. Additionally, automated image analysis methods were developed to further simply quantitative measurements when using colorimetric substrates on paper-based platforms. The second application illustrates the transition of a clinical laboratory-based influenza assay to a one-step, POC-style muPAD which is capable of determining if a sample contains influenza and if an antiviral treatment would be effective. The muPAD was optimized to detect multiple strains of Influenza A and B, as well as determine if potential interferents, such as Streptococcus pneumoniae, are present in the sample. Operation of the muPAD simply involved adding a sample to the top port; the sample then transferred to four different reagent zones, and enzymatic reactions under different buffer conditions took place on the bottom of the device. Analysis can be performed by eye or through a colorimetric image analysis smartphone app. The muPAD produced excellent results for all influenza types and sub-types tested. There is enormous potential for this type of device in not only limited resource environments, but in first world countries as well. Both of these applications demonstrate how μPADs can be used as versatile platforms for performing clinical-laboratory assays as POC devices. |
