Remote Calorimetric Biosensing For Clinical Diagnostic Applications
Open Access
- Author:
- Gaddes, David Edwin
- Graduate Program:
- Bioengineering
- Degree:
- Doctor of Philosophy
- Document Type:
- Dissertation
- Date of Defense:
- August 29, 2016
- Committee Members:
- Srinivas Tadgiadapa, Dissertation Advisor/Co-Advisor
- Keywords:
- Biosensor
calorimetry
microfabrication
enzyme immobilization - Abstract:
- The medical community increasingly relies on quantification of biomarkers in blood, urine, and saliva to monitor treatments and screen for diseases. While glucose meters have been around since the 1980s only two biosensors have gained success in commercial applications, the glucose meter and the pregnancy test. The majority of biomarkers are quantified using a benchtop analytical system developed specifically for one biomarker. We developed a portable, calorimetric biosensor, which has the capability of quantifying a large variety of biomarkers. Specifically, our goal was to develop this biosensor to quantify creatinine in human urine samples. Further, we sought to develop a sensitive and robust calorimeter, in which the enzyme containing cartridge could be quickly removed and replaced. To achieve this, we implemented a highly sensitive Y-cut quartz crystal resonator as the sensing mechanism in this calorimetric biosensor. The high-temperature sensitivity of the quartz resonator enables a sensitive calorimetric system despite the separation between the fluid of interest and the sensor through 100 μm gap of air. Moreover, to further improve the calorimetric performance of this device we implemented a second quartz resonator, which acts as a reference sensor to eliminate spurious noise from thermal fluctuations. Additionally, we evaluate three enzyme immobilization techniques: glutaraldehyde crosslinking, electrostatic layer-by-layer immobilization, and alginate entrapment using both a fluorescent assay and the calorimetric biosensor. This work is concluded by quantifying the concentration of creatinine in human urine samples. The creatinine concentrations determined using the biosensors were compared against those determined through an HPLC technique. This Ph.D. work has successfully demonstrated the development of a calorimetric biosensor, specifically for the quantification of creatinine in human urine samples.