Mussel-inspired Multifunctional Polymeric Materials with Bioengineering Applications

• Author / Creator

  Li, Lin

• Mussels can obtain strong underwater attachment to virtually all kinds of surfaces including rocks, metals, wood structures, polymers and concretes by secreting mussel foot proteins to form byssus. Great efforts have been dedicated to understanding this behavior and it is found that an catecholic amino acid 3,4-dihydroxyphenyl-L-alanine (DOPA) plays a crucial role in achieving this remarkable adhesion performance by actively involved in various catechol-mediated interactions such as covalent bonding, hydrogen bonding, metal coordination, cation-π interaction and aromatic interaction. Recently the self-healing capability of myssel byssal threads has attracted great attention and it is found that catechol-mediated reversible interactions such as catechol-metal coordination, catechol-boronate dynamic covalent interaction and hydrogen bonding also contribute to the recovery of material structure after damage. Inspired by all these interactions actively functioned in aqueous environment, numerous polymeric materials with various bioengineering applications can be designed and developed. In this thesis, a detailed review on mussel adhesion behaviors and various mussel-inspired polymeric materials based on different DOPA chemistry was presented first followed by three original research projects on developing novel mussel-inspired functional polymers for bioengineering applications, using reversible addition-fragmentation chain transfer (RAFT) polymerization. In the first project, a versatile approach to prepare antifouling coatings bearing polymer loops was demonstrated. An ABA triblock copolymer employing catechol-functionalized poly(N,N-dimethylacrylamide) (PDMA) as the adhesive A block and poly(ethylene glycol) (PEG) as the antifouling B block was prepared. By simple drop coating, this triblock copolymer can form a layer of loops onto substrate surface with the assistance of two adhesive anchoring blocks, which is compared with a layer of brushes prepared by drop-coating an AB diblock copolymer with the same anchoring block and half of the middle PEG chain length. The protein adsorption tests using quartz crystals microbalance with dissipation (QCM-D) demonstrate that the loops-coated surfaces show enhanced antifouling performance over the brushes-coated surfaces with similar end graft density. In the second project, a novel injectable self-healing hydrogel with anti-biofouling property was preapred and new mussel-inspired self-healing mechanisms, catechol-mediated hydrogen bonding and aromatic interactions, were unveiled. An ABA triblock copolymer using catechol-functionalized poly(N-isopropylacrylamide) (PNIPAM) as the thermo-sensitive A block and poly(ethylene oxide) (PEO) as the hydrophilic and antifouling B block was synthesized. The hydrogel prepared through self-assembly of this triblock copolymer exhibits excellent thermo-sensitivity and antifouling performance. Surprisingly this hydrogel can withstand repeated deformation and recover its mechanical properties and structure within seconds in metal-free aqueous environment. By characterizing hydrogels prepared by different triblock copolymers, it is concluded that catechol-mediated hydrogen bonding and aromatic interactions are responsble for achieving this remarkable self-healing performance. In the third project, an injetable self-healing hydrogel with antimicrobial and antifouling properties was prepared. An ABA tri-block copolymer employing catechol functionalized PEG as the thermo-sensitive A block and poly{[2-(methacryloyloxy)-ethyl] trimethyl ammonium iodide}(PMETA) as the hydrophilic and antimicrobial B block was synthesized. The hydrogel prepared through self-assembly of this triblock copolymer shows excellent sol-gel thermo-reversibility, can effectively inhibit the growth of E. coli (>99.8% reduction in bacterial counts) and prevent nonspecific cell attachment. What’s more, it can heal autonomously from repeated damage, through mussel-inspired catechol-mediated hydrogen bonding and aromatic interactions, exhibiting great potential in various bioengineering applications.

• Subjects / Keywords

  • Polymer brushes
  • Hydrogels
  • Antimicrobial
  • DOPA
  • Catechol
  • Self-healing
  • Polymer loops
  • Mussel-inspired
  • Antifouling

• Graduation date

  Spring 2017

• Type of Item

  Thesis

• Degree

  Doctor of Philosophy

• DOI

  https://doi.org/10.7939/R3RJ4967H

• License

  This thesis is made available by the University of Alberta Libraries with permission of the copyright owner solely for non-commercial purposes. This thesis, or any portion thereof, may not otherwise be copied or reproduced without the written consent of the copyright owner, except to the extent permitted by Canadian copyright law.