Goda, Sarah
(2024)
Advances in the Development of Photonic Crystal Hydrogels as Versatile Biomolecular Sensors.
Doctoral Dissertation, University of Pittsburgh.
(Unpublished)
Abstract
We expanded the understandings of photonic crystal hydrogel fabrication and swelling behavior pertaining to their use as sensing materials. Our hydrogels are comprised of a polymer network containing a recognition group and a photonic crystal array embedded within the hydrogel network. The molecular recognition groups within the hydrogel allow us to make these sensors highly selective to target analytes. Hydrogel changes from analyte binding result in a volume phase transition (VPT). Hydrogel VPTs alter the distance between particles that make up the photonic crystal array, leading to changes in diffracted light according to the Bragg condition. Studies reported herein demonstrate the use of photonic crystal hydrogel sensors as sensing platforms that are easily adaptable.
We investigated the use of oxyamine functionalized hydrogels to monitor lactate dehydrogenase’s enzymatic conversion of lactate to pyruvate. Pyruvate’s covalent attachment to the hydrogel enables a swelling response which corresponds to lactate concentrations in solution. We detected < 0.5 mM lactate in buffer solutions within an hour with detection limits < 4 mM lactate in serum solutions. This work is the first to demonstrate indirect detection of analytes by coupling enzymatic reactions with photonic crystal hydrogel sensors.
DNA aptamers are small biomolecules that are highly selective in their binding and are stable under a variety of conditions. We incorporated hybridized DNA aptamers into 2DPC hydrogels forming crosslinks. These DNA crosslinks break due to analyte-DNA binding which enables hydrogel swelling. We demonstrated this aptamer sensing motif is easily modified from detecting the small molecule adenosine to the large protein thrombin.
Poly (N-isopropylacrylamide) (pNIPAM) hydrogels are thermoresponsive, undergoing large VPTs at temperatures above their lower critical solution temperature (LCST). pNIPAM’s LCST is shifted due to changes in the hydrophobicity of pNIPAM’s environment from disruptions to pNIPAM’s solvation shell. This enables detection of hydrophobic analytes that can typically require complex detection methods. We are the first to investigate using shifts in pNIPAM’s LCST for detection of hydrophobic analytes such as Xe. We spectroscopically investigated Xe-protein binding to monitor favorable Xe binding environments and increase pNIPAM’s sensitivity to the presence of Xe.
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Details
| Item Type: |
University of Pittsburgh ETD
|
| Status: |
Unpublished |
| Creators/Authors: |
|
| ETD Committee: |
|
| Date: |
10 January 2024 |
| Date Type: |
Publication |
| Defense Date: |
16 October 2023 |
| Approval Date: |
10 January 2024 |
| Submission Date: |
6 November 2023 |
| Access Restriction: |
No restriction; Release the ETD for access worldwide immediately. |
| Number of Pages: |
189 |
| Institution: |
University of Pittsburgh |
| Schools and Programs: |
Dietrich School of Arts and Sciences > Chemistry |
| Degree: |
PhD - Doctor of Philosophy |
| Thesis Type: |
Doctoral Dissertation |
| Refereed: |
Yes |
| Uncontrolled Keywords: |
Photonic Crystals, Hydrogels, Sensors |
| Date Deposited: |
10 Jan 2024 13:40 |
| Last Modified: |
10 Jan 2024 13:40 |
| URI: |
http://d-scholarship.pitt.edu/id/eprint/45495 |
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