All ETDs from UAB

Advisory Committee Chair

Aaron Catledge

Advisory Committee Members

Simien Clayton

Vinoy Thomas

Yogesh Vohra

Vinoy Thomas

Document Type

Dissertation

Date of Award

2020

Degree Name by School

Doctor of Philosophy (PhD) College of Arts and Sciences

Abstract

Creatinine measurement is an important diagnostic test for assessing kidney health. This work represents our current progress in creatinine artificial sensor based on a molecularly imprinted polymer of polyacrylamide hydrogel and nanodiamonds fluorescence change. For a 0.3 mM creatinine rebinding solution, an imprinting factor of 2.54 was measured. Also, a molecularly imprinted polymer was obtained by incorporating nanodiamond into a creatinine-imprinted polyacrylamide hydrogel. The quenching of peak nanodiamond fluorescence was significantly higher in the creatinine-imprinted polymer compared to the non-imprinted polymer, indicative of higher creatinine affinity in the imprinted polymer. Nanodiamond fluorescence from nitrogen-vacancy color centers (NV- and NV0) was also used to detect creatinine based on nanodiamond-creatinine surface charge interaction. Results show a 15% decrease of NV-/NV0 emission ratio for the creatinine-imprinted polymer compared to the non-imprinted polymer and are explained in terms of changes in the near-surface band structure of nanodiamonds with the addition of creatinine. In addition, we developed a washing method to increase the removal of creatinine molecules from the MIP network. Results showed nanodiamonds that located next to the binding sites experienced fluorescence quenching after rebinding of creatinine to imprinted polymer higher than the non- imprinted one. The imprinting factor was found to be 5.05±2.15 which being excellent progress compared to previous work. We also, prepared NDs thin films using the spin coating method and found that mixing nanodiamonds with zinc oxide nanospheres in DI water or ethanol could enhance the formation of thin films. We studied the optical properties for nanodiamonds in thin films and solutions such as FTIR, absorbance, and transmittance spectroscopies. The minimum bandgap for nanodiamonds was calculated and found to be 3.5 e V. Results demonstrate that the imprinted hydrogel can be effectively used as an imprinting platform in aqueous solution for preserving bioactivity of creatinine. With further improvement of sensor design to better disperse nanodiamond within the hydrogel, fluorescent sensing from nitrogen- vacancy centers is expected to yield higher sensitivity with a longer range (Coulombic) interaction to imprinted sites than that for a sensor based on acceptor/donor resonance energy transfer.

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