The Development of Three-Dimensional, Paper-Based Microfluidic Devices for Applications in Point-of-Care Diagnostics.
Fernandes, Syrena.
2019
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Healthcare providers face unique challenges in limited-resource settings because current diagnostic approaches rely heavily on expensive equipment operated by skilled technicians. An ideal analytical platform for use at the point-ofcare must be low-cost, equipment-free, and operationally simple for users with minimal training. In this dissertation, we discuss the use of patterned paper as a platform ... read morefor the development of low-cost microfluidic devices and analytical tests that are designed for use in limited-resource settings. In Chapter 1, we introduce the utility of paper as an analytical platform by highlighting different properties of paper and explaining how they contribute to the development and performance of paper-based microfluidic devices. We discuss a number of detection methods that have been employed to detect soluble analytes, such as proteins and small molecules, within paper-based microfluidic devices. Finally, we discuss how, by considering all of these properties, paper-based devices can be designed to enable cellular assays for use at the point-of-care, which has remained an outstanding challenge. In Chapter 2, we demonstrate the potential of paper-based microfluidic devices by describing the development of a three-dimensional device architecture to perform immunoassays in patterned paper. These paper-based devices use a combination of lateral and vertical flow to control the wicking of fluid in three dimensions. We provide guidelines to aid in the design of these devices and we illustrate how patterning can be used to tune the duration and performance of the assay. We demonstrate the use of these paper-based devices by developing a sandwich immunoassay for human chorionic gonadotropin (hCG) in urine, a biomarker of pregnancy. We then directly compare the qualitative and quantitative results of these paper-based immunoassays to commercially available lateral flow tests (i.e., the home pregnancy test). Our results suggest paper-based devices may find broad utility in the development of immunoassays for use at the point-ofcare. In Chapter 3, we expand upon the applications of our three-dimensional, paper-based microfluidic device by detecting antibodies specific for HIV gp41 antigen in serum. The ability to detect antibodies that are generated during an immune response is integral to the diagnosis and monitoring of infections. Assays that have been applied to the detection of antibodies are classically referred to as indirect immunoassays, which include three different formats: indirect, doubleantigen sandwich, and total IgG capture. Each of these three approaches relies on a unique pair of reagents to capture the target antibody and transduce a detectable signal, which permits assays to be tuned for ideal performance based on the availability and quality of reagents, the resources available to the operator, and the complexity of the sample (e.g., serum vs. saliva). This flexibility, however, can complicate the development of diagnostic tests and increase the complexity of the devices required to perform them. Therefore, in Chapter 3, we compare the performances of these indirect immunoassays by developing assays for the HIV antibodies in human serum to ultimately show that our three-dimensional paperbased device has broad potential for the development of paper-based immunoassays. In addition to detecting soluble analytes in paper-based microfluidic devices, we demonstrate our ability to use paper as a platform for cellular assays. Specifically, in Chapter 4, we describe a paper-based microfluidic device that enables the controlled transport of red blood cells (RBC) and the measurement of the hematocrit—the ratio of RBC packed cell volume to total volume of whole blood—which offers critical information about the health status of a patient. The properties of paper, device treatment, and device geometry affect the overall extent and reproducibility of transport of RBCs. Ultimately, we developed an inexpensive (US$0.03 per device) thermometer-styled device where the distance traveled by RBCs is proportional to the hematocrit. These results provided a foundation for the design of paper-based microfluidic devices that enable the separation and detection of cells in limited-resource settings. Finally, in Chapter 5, we describe the development of a three-dimensional, paper-based microfluidic device uniquely capable of controlling the transport of a sample of whole blood to separate and analyze individual blood components (i.e., hemolysate, purified plasma, and intact red blood cells) in parallel. As a proof-ofconcept, we chose three assays that have been proven to function in paper to demonstrate the multiplexing capabilities of our blood processing device. We used a blood typing assay to analyze intact RBCs and detected a biomarker, C-reactive protein, in purified plasma. We discuss our future plans for analyzing hemolysate by integrating a glucose 6 phosphate dehydrogenase assay into our device. Our successful execution of all three assays using a sample of whole blood in a single paper-based microfluidic device will expand the development of blood-based assays for use at the point-of-care.
Thesis (Ph.D.)--Tufts University, 2019.
Submitted to the Dept. of Chemistry.
Advisor: Charles Mace.
Committee: Samuel Kounaves, David Walt, and Matthew Lockett.
Keyword: Chemistry.read less - ID:
- 2801pv35g
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