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Bio-based nonionic antimicrobial polymers with isatin or indole functionality

Li, Xiaoya LU (2021)
Abstract
Infections by pathogenic microorganisms remain one of the most serious concerns in several areas, particularly in hygienic applications. Antimicrobials have been used to combat these infections. Using small molecular antimicrobials as additives or coatings is an industrially adopted strategy. However, small antimicrobial agents always suffer from many drawbacks, such as leaching potential, toxicity to the environment, antimicrobial resistance. The development of antimicrobial polymers provides a promising strategy to overcome these issues. Compared to small molecular antimicrobials, antimicrobial polymers have advantages like enhanced antimicrobial efficiency, reduced toxicity, longer lifetime and lower risk to develop antimicrobial... (More)
Infections by pathogenic microorganisms remain one of the most serious concerns in several areas, particularly in hygienic applications. Antimicrobials have been used to combat these infections. Using small molecular antimicrobials as additives or coatings is an industrially adopted strategy. However, small antimicrobial agents always suffer from many drawbacks, such as leaching potential, toxicity to the environment, antimicrobial resistance. The development of antimicrobial polymers provides a promising strategy to overcome these issues. Compared to small molecular antimicrobials, antimicrobial polymers have advantages like enhanced antimicrobial efficiency, reduced toxicity, longer lifetime and lower risk to develop antimicrobial resistance.

Most research has been focused on cationic antimicrobial polymers which can disrupt bacterial membranes by electrostatic interactions. The major issues with cationic antimicrobial polymers are their undesirable high-water solubility, toxicity, fouiling potential and poor miscibility with nonionic polymer matrices. To solve these problems, continued exploration of new nonionic antimicrobial polymers is highly valuable and that is where this thesis has been focusing on.

In this work, we have designed and synthesized different nonionic antimicrobial polymers with isatin or indole functionality, including hyperbranched and linear structures. The antimicrobial properties against various bacteria of these polymers were evaluated. In general, these bio-based polymers exhibited significant antimicrobial activity, higher than their corresponding small model compounds. We also found that ether unit may have a synergistic effect to interact with certain bacterial membranes. It was also observed that the N-H moiety of indole in the polymer’s structure facilitate the hydrogen bonding with the C=O moiety of polyesters, which improved their miscibility. Finally, we evaluated the hemolytic activity and cytotoxicity of the obtained polymers. As a result, they showed negligible cytotoxic effect to red blood cells and MG-63 osteoblast-like cells, which indicates their potential in biomedical applications.
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Please use this url to cite or link to this publication:
author
supervisor
opponent
  • Dr. Palermo, Edmund, Rensselaer Polytechnic Institute, USA
organization
publishing date
type
Thesis
publication status
published
subject
keywords
antimicrobial polymers, nonionic, isatin, indole, miscibility, hemolytic activity, cytotoxicity
pages
230 pages
publisher
Polymer and Materials Chemistry (LTH), Lund University
defense location
Lecture hall KC:A, Kemicentrum, Naturvetarvägen 14, Faculty of Engineering LTH, Lund University, Lund
defense date
2022-01-24 14:00:00
ISBN
978-91-7422-851-9
978-91-7422-850-2
language
English
LU publication?
yes
id
7b9b82fc-6cc1-4887-979a-dc14b295cb69
date added to LUP
2021-12-14 13:30:58
date last changed
2022-04-12 14:54:47
@phdthesis{7b9b82fc-6cc1-4887-979a-dc14b295cb69,
  abstract     = {{Infections by pathogenic microorganisms remain one of the most serious concerns in several areas, particularly in hygienic applications. Antimicrobials have been used to combat these infections. Using small molecular antimicrobials as additives or coatings is an industrially adopted strategy. However, small antimicrobial agents always suffer from many drawbacks, such as leaching potential, toxicity to the environment, antimicrobial resistance. The development of antimicrobial polymers provides a promising strategy to overcome these issues. Compared to small molecular antimicrobials, antimicrobial polymers have advantages like enhanced antimicrobial efficiency, reduced toxicity, longer lifetime and lower risk to develop antimicrobial resistance.<br/><br/>Most research has been focused on cationic antimicrobial polymers which can disrupt bacterial membranes by electrostatic interactions. The major issues with cationic antimicrobial polymers are their undesirable high-water solubility, toxicity, fouiling potential and poor miscibility with nonionic polymer matrices. To solve these problems, continued exploration of new nonionic antimicrobial polymers is highly valuable and that is where this thesis has been focusing on.<br/><br/>In this work, we have designed and synthesized different nonionic antimicrobial polymers with isatin or indole functionality, including hyperbranched and linear structures. The antimicrobial properties against various bacteria of these polymers were evaluated. In general, these bio-based polymers exhibited significant antimicrobial activity, higher than their corresponding small model compounds. We also found that ether unit may have a synergistic effect to interact with certain bacterial membranes. It was also observed that the N-H moiety of indole in the polymer’s structure facilitate the hydrogen bonding with the C=O moiety of polyesters, which improved their miscibility. Finally, we evaluated the hemolytic activity and cytotoxicity of the obtained polymers. As a result, they showed negligible cytotoxic effect to red blood cells and MG-63 osteoblast-like cells, which indicates their potential in biomedical applications.<br/>}},
  author       = {{Li, Xiaoya}},
  isbn         = {{978-91-7422-851-9}},
  keywords     = {{antimicrobial polymers, nonionic, isatin, indole, miscibility, hemolytic activity, cytotoxicity}},
  language     = {{eng}},
  month        = {{12}},
  publisher    = {{Polymer and Materials Chemistry (LTH), Lund University}},
  school       = {{Lund University}},
  title        = {{Bio-based nonionic antimicrobial polymers with isatin or indole functionality}},
  url          = {{https://lup.lub.lu.se/search/files/110940839/e_nailing_ex_xiaoya.pdf}},
  year         = {{2021}},
}