Author

Shan Hazoor

Graduation Semester and Year

2022

Language

English

Document Type

Dissertation

Degree Name

Doctor of Philosophy in Chemistry

Department

Chemistry and Biochemistry

First Advisor

Frank W Foss

Abstract

Polydiacetylene (PDA) polymers are conjugated macromolecules with desirable sensing properties. The presence of alternate double and triple bonds (en-yne subunits) generates electron delocalization in the PDA backbone, yielding a characteristic blue color, which changes to red upon environmental perturbations to the conjugated backbone structure. In chapter 1 PDA polymers containing a functional monomer 10,12- pentacosadiynoic acid-vancomycin conjugate (PCDA-Van) were prepared. Syntheses of different monomers containing different polar head groups were carried out to investigate a compatible monomer with PCDA-van stability. Gram-positive bacterial cell wall sequencing oligopeptides (OP) D-Ala-D-Ala and L-Lys-D-Ala-D-Ala were synthesized as a model for bacterial sensing. The PCDA-Van provided rapid and direct detection of OP visibly through a blue to purple color transition upon the addition of OP. PCDA-Van containing liposomes became fluorescent in the presence of S. aureus. In chapter 2, PCDA-peptide was synthesized for the detection of gram-positive bacteria Methicillin-resistant Staphylococcus aureus (MRSA). PDA-peptide stability was optimized by using three monomer system to prepare liposomal polymer. PDA-peptides were labelled with a dabsyl-labeled lipid to obtain fluorescent images to analyze the bacterial interaction with liposomes. Next, a diphenyl diacetylene (DA) linker was synthesized, coupled with peptides (Pep-DA-Pep), to prepare a PDA containing hydrogel with pH sensing applications. At acidic pH, antimicrobial agents were incorporated into the PDA hydrogel and upon elevated pH gel-to-sol transition delivered the drug to the target alkaline infection site. In chapter 3, the ability of biomimetic molecules to control the carbonation and precipitation process of CaCO3 in cementitious materials was investigated. The purpose of the study was to enhance the stability and function of cementitious material. A series of different bisphosphonate (BPs) molecules were synthesized, containing different alkyl chains and a distal functional group. Experiments were performed with CaCl2 solution in the presence of different BPs moieties for CaCO3 precipitations. BPs with longer alkyl chain molecules showed the enhanced formation of vaterite and amorphous calcium carbonate (ACC). Characterization of the precipitation was done with atomic force microscopy (AFM), thermogravimetric analysis (TGA), conductivity experiments, Fourier transform infrared spectroscopy (FTIR) and was supported with computational studies. In chapter 4, future work is described to further our study on the biosensing of infective species and the preparation of metal carbonate binding molecules to target bacterial species and effect on CaCO3 precipitation respectively.

Keywords

Polydiacetylene, Biomimetic molecules, Bisphosphonates

Disciplines

Chemistry | Physical Sciences and Mathematics

Comments

Degree granted by The University of Texas at Arlington

Included in

Chemistry Commons

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