Skip to Main Content
 

Global Search Box

 
 
 
 

Files

File List


41655.pdf (6.3 MB)

ETD Abstract Container

Abstract Header

Membrane and Device Strategies for Improving the Detection limit and Longevity of Electrochemical Aptamer-based Sensors in Real Biofluids

Yuan, Yuchan
http://rave.ohiolink.edu/etdc/view?acc_num=ucin1649860239183501

Abstract Details

2022, PhD, University of Cincinnati, Engineering and Applied Science: Electrical Engineering.
It is commonly acknowledged that the continuous glucose monitor for diabetes management is a historical achievement of modern diagnostics technology. However, it has been the only success despite acute needs for the real-time monitoring of many other molecules across the broader field of human disease management such as cardiac, drug dosing, fertility and other problems. The limitation is that the well-studied commercially available glucose sensors are enzymatic, which makes it very difficult to generalize its working mechanism to other analytes. Meanwhile, unlike enzymatic sensors, electrochemical aptamer-based sensors are broadly generalizable, demonstrated by several examples of real-time, in-vivo molecular monitoring at nanomolar to micromolar concentrations. So far, electrochemical aptamer-based (EAB) sensor demonstrations are highly prevalent for testing in buffer fluid or blood. This should not be surprising because the testing criteria for these fluids are highly applicable and because both fluids are well-buffered in their pH and salinity. Aptamers are known to be sensitive to both salinity and pH, thus affecting sensor output and analyte response. However, some emerging biofluids for biosensing such as human sweat or environmental fluids can have widely ranging pH and salinity. In this dissertation, a novel oil membrane sensor protection technique is reported against changes in pH and salinity for EAB sensors, where a thin, semi-permeable hydrophobic membrane will allow the target hydrophobic analyte diffuse to the sensor through while preventing diffusion of hydrophilic interferents (proteins, acids, bases, etc.). The encapsulated EAB cortisol sensor can perform in a pseudo real-time manner (5-minute concentration-on rise time and 10-minute concentration-off down time) and maintains measurement signal for at least 7 hours even in the extreme acidic solution of pH 3. EAB sensors conventionally bond the aptamer to a gold working electrode via thiol linkage. However, with oil-membrane protection technique, the aptamers can also be deployed in solution because the membrane will prevent the aptamers from diffusing away from the active electrode. Leveraging a well-studied optical cortisol aptamer for proof of concept, a solution-phase cortisol aptamer sensor is also shown to have higher sensitivity in solution-phase operation, with 5% signal increase for as little as 10 nM cortisol concentration. This dissertation presents a simple and elegant sensor protection method and an innovative signal transduction mechanism for EAB sensors such as cortisol for continuous stress monitoring. The results not only enable a continuous cortisol monitor using EAB sensor that works robustly regardless of biofluid conditions, but also demonstrate new aptamer switching methods such as solution-phase aptamer sensors.
Jason Heikenfeld, Ph.D. (Committee Member)
Michael Brothers, Ph.D. (Committee Member)
Ryan White, Ph.D. (Committee Member)
Andrew Steckl, Ph.D. (Committee Member)
Leyla Esfandiari, Ph.D. (Committee Member)
108 p.
Electrical Engineering
Electrochemical Aptamer-based Sensor; sensor detection limit; sensor longevity

Recommended Citations

Citations

  • Yuan, Y. (2022). Membrane and Device Strategies for Improving the Detection limit and Longevity of Electrochemical Aptamer-based Sensors in Real Biofluids [Doctoral dissertation, University of Cincinnati]. OhioLINK Electronic Theses and Dissertations Center. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1649860239183501

    APA Style (7th edition)

  • Yuan, Yuchan. Membrane and Device Strategies for Improving the Detection limit and Longevity of Electrochemical Aptamer-based Sensors in Real Biofluids. 2022. University of Cincinnati, Doctoral dissertation. OhioLINK Electronic Theses and Dissertations Center, http://rave.ohiolink.edu/etdc/view?acc_num=ucin1649860239183501.

    MLA Style (8th edition)

  • Yuan, Yuchan. "Membrane and Device Strategies for Improving the Detection limit and Longevity of Electrochemical Aptamer-based Sensors in Real Biofluids." Doctoral dissertation, University of Cincinnati, 2022. http://rave.ohiolink.edu/etdc/view?acc_num=ucin1649860239183501

    Chicago Manual of Style (17th edition)

ucin1649860239183501
218
© 2022, all rights reserved.
This open access ETD is published by University of Cincinnati and OhioLINK.
Release 3.2.12