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Design, Synthesis, Characterization and Testing of Materials for Biomedical Applications

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thesis
posted on 30.10.2019, 17:54 by Orsolya Karácsony
In an era when antiobiotics and sanitizers are readily available, but running out of fossil fuel is not an immediate danger yet, the lengthening of lifetime and the increasement of life quality became mostly dependent on our ability to replace body parts lost by illness or accident, which places
biomimetic and antifouling materials in the spotlight of the first half of the 21st century. In this thesis, step-growth polymerization (SGP) and atom transfer radical polymerization (ATRP) were utilized in the design of synthetic polymers to create biomimetic and antifouling materials, with control over structure and functionality. Biomimetic conjugates were prepared using SGP by a
“click” reaction between a genetically engineered green fluorescent protein (GFP) bearing two azides and a dialkyne poly(ethylene glycol) (PEO). SGP and thermosensitive, coating forming hyaluronic acid (HA) - poly(di(ethylene glycol) methyl ether methacrylate) (P((MEO)2MA))
conjugates were prepared by synthesizing the thermoresponsive polymer by ATRP using an aminated initiator, then coupling it to the carboxylic acid froups of the activated HA. The HAP((MEO)2MA) conjugates were tested for their antifouling property. Then, these conjugates were
synthesized with different grafting densities (GD) and P((MEO)2MA) side chain length values, in order to find the ideal parameters for an antifouling coating material and to elucidate the mechanism of coating formation. Over the course of the characterization of both types of materials,
intriguing physical behavior was encountered. The GFP-PEO behaves like a wooden snake and the HA- P((MEO)2MA) conjugates show an intriguing mechanism of film formation. Both behaviors were explored using various physical characterization techniques, among which atomic
force microscopy (AFM) was crucial. As an important technique, AFM as a technique is isolated for study. As part of my work, the dependence of average tip-sample forces on imaging conditions such as set-point ratio and operating frequency were explored. First, the derivation of an analytical
expression for the average tip-sample force will be presented. Its predictions will be then shown to be in excellent agreement with the results of numerical simulations using a single degree of freedom, driven damped harmonic oscillator model of tapping mode AFM. In multi-frequency tapping-mode AFM (TM-AFM) experiments, quantifying the tip-sample force may be essential in
understanding the nature of contrast in imaging soft materials such as block copolymers or novel complex macromolecular architectures, such as the conjugates described in this thesis.

History

Date

11/05/2015

Degree Type

Dissertation

Department

Chemistry

Degree Name

  • Doctor of Philosophy (PhD)

Advisor(s)

Newell Washburn

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