A paper-based point-of-care molecular diagnostic platform for the developing world
Rodriguez, Natalia Maria
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The disproportionate burden of infectious disease and lack of appropriate diagnostic tools in the developing world suggest that future health technology development efforts need to more effectively target these resource-limited settings. Microfluidic systems, like lab-on-a-chip technologies, offer the potential to miniaturize the large, complex processes performed in first-world laboratories onto a portable chip for use in remote settings. The problem with these systems is that they require equipment for fluidic handling and many other aspects of diagnostic assays such as sample preparation and analyte detection. The notion of “paperfluidics” has garnered much attention due to paper’s natural ability to wick fluids through capillary action without the need for pumps or other equipment. This and many other qualities of paper make it well suited for point-of-care diagnostics. Paper diagnostics have successfully been employed to detect the presence of antigens or small molecules in clinical samples; however, the detection of many disease targets relies on the much higher sensitivity and specificity of molecular diagnostics achieved via nucleic acid amplification tests (NAAT). The work presented in this dissertation describes the design and development of a paperfluidic sample-to-answer NAAT platform. Preliminary work focused on the development of separate NAAT modules for the extraction, amplification, and detection of nucleic acids from clinical samples directly within a paper matrix. A paper-based assay was developed, using Influenza A (H1N1) as a model system, for the extraction and purification of RNA directly from patient nasopharyngeal specimens, in situ isothermal amplification, and immediate lateral flow detection of amplified products. We then integrate these paper-based NAAT modules onto a single paperfluidic chip in a modular, foldable system that allows for fully-integrated fluidic handling from sample to answer. We showcase the full functionality of the chip by extracting, amplifying and detecting human papillomavirus (HPV) 16 DNA directly from crude cervical specimens in less than 1 hour, for early point-of-care detection of cervical cancer. The chip is made entirely of paper and adhesive sheets, making it low-cost, portable, and disposable, offering the potential for use in very remote settings and increasing access to screening to those most in need.