Toward point-of-care molecular quantification : novel assays and detection strategies for biosensing in complex media
Abstract/Contents
- Abstract
- Molecular quantification at the point-of-care offers a pathway toward personalized and accessible medicine. Rapid characterization of varying biomarker concentrations can enable timely intervention and preventative care. However, in order to function at the point-of-care, biosensors must perform rapidly and directly in complex biofluids such as blood. These biofluids create challenging environments, frequently causing biofouling, signal degradation, and nonspecific binding on the sensor surface. Overcoming these challenges requires innovation in both assay design and detection hardware in order to develop truly point-of-care devices. In this thesis, I first discuss three major objectives of point-of-care devices - (1) an actionable time-to-answer, (2) the ability to perform directly in patient samples, and (3) minimal patient inconvenience. Through this lens, I discuss the development of both custom hardware and novel fluorescent assays to enable rapid molecular quantification directly in complex media. I begin by presenting a custom fiber optic-based biosensor which leverages evanescent sensing to selectively interrogate the surface of the fiber probe, minimizing interference from the background biofluid. I then present two projects applying this biosensor to the detection of two classes of biomarkers. In the first project, I discuss the adaptation of existing aptamers, single stranded nucleic acid sequences that bind to target molecules, into fluorescently-labeled switches to enable continuous monitoring of small molecules. I then present the use of these aptamer switches in conjunction with our custom biosensor to continuously detect dopamine and cortisol in artificial cerebrospinal fluid and undiluted plasma, respectively. In the second project, I present the development of a generalizable fluorescent substrate architecture to detect enzymatic cleavage. This architecture has been coupled with our sensor to rapidly detect the activity of Factor Xa, an enzyme in the coagulation pathway, directly in whole human blood. Following this, I present a third project in which a triple-binding immunoassay is amplified by Hybridization Chain Reaction, a DNA self-assembly reaction, to establish a high signal to noise ratio assay. I discuss the potential optimization and integration of this amplified immunoassay with our fiber-based biosensor to enable rapid, low abundance protein detection at the point-of-care. Finally, I present a proof-of-concept work that makes use of 3D-printed scaffolding to pattern a hydrogel filter, allowing for the development of a point-of-care device that allows for filtration of target molecules out of complex media prior to optical detection. Together, these projects demonstrate a significant advance toward the ability to rapidly quantify biomarkers directly in complex media, providing a promising path toward more generalized point-of-care biosensing.
Description
| Type of resource | text |
|---|---|
| Form | electronic resource; remote; computer; online resource |
| Extent | 1 online resource. |
| Place | California |
| Place | [Stanford, California] |
| Publisher | [Stanford University] |
| Copyright date | 2023; ©2023 |
| Publication date | 2023; 2023 |
| Issuance | monographic |
| Language | English |
Creators/Contributors
| Author | Cartwright, Alyssa |
|---|---|
| Degree supervisor | Soh, H. Tom |
| Thesis advisor | Soh, H. Tom |
| Thesis advisor | Appel, Eric (Eric Andrew) |
| Thesis advisor | Vuckovic, Jelena |
| Degree committee member | Appel, Eric (Eric Andrew) |
| Degree committee member | Vuckovic, Jelena |
| Associated with | Stanford University, School of Engineering |
| Associated with | Stanford University, Department of Electrical Engineering |
Subjects
| Genre | Theses |
|---|---|
| Genre | Text |
Bibliographic information
| Statement of responsibility | Alyssa P. Cartwright. |
|---|---|
| Note | Submitted to the Department of Electrical Engineering. |
| Thesis | Thesis Ph.D. Stanford University 2023. |
| Location | https://purl.stanford.edu/mg224xm9855 |
Access conditions
- Copyright
- © 2023 by Alyssa Cartwright
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