h1

%0 Thesis
%A Vorobii, Mariia
%T Spatially-resolved surface initiated controlled radical polymerization of antibiofouling brushes
%I RWTH Aachen University
%V Dissertation
%C Aachen
%M RWTH-2025-01441
%P 1 Online-Ressource : Illustrationen
%D 2025
%Z Veröffentlicht auf dem Publikationsserver der RWTH Aachen University
%Z Dissertation, RWTH Aachen University, 2025
%X Medical devices and implants have significantly advanced healthcare and improved patient outcomes. However, they continue to face the challenge of imperfect biocompatibility with the surrounding biological milieu. At the molecular level, this issue often begins with nonspecific protein adsorption, leading to adverse reactions such as activation of the coagulation cascade and biofilm formation, which can compromise device function and pose risks to patient health. Therefore, developing effective antifouling coatings is essential to enhance biocompatibility and ensure the safe and reliable performance of medical devices and implants. The most promising antifouling coatings to date are "grafted-from" polymer brushes, which provide several physical barriers against adsorption. However, their performance depends on the precise control of the polymerization process, which was a key challenge at the start of this doctoral research. This thesis primarily focuses on developing a new “living” surface-initiated polymerization method for the synthesis of hydrophilic antifouling polymer brushes. Photoinduced single-electron transfer living radical polymerization (SET-LRP) in solution was optimized for surface-initiated polymerization, enabling a significant improvement in control over the polymerization process and drastically reducing the required copper catalyst concentration from milligram levels to just a few parts per billion (ppb). This thesis outlines a step-by-step optimization of polymerization protocols, beginning with acrylates and concluding with the more challenging zwitterionic methacrylamides. The developed methods enable controlled polymerization of over 20 different monomers. In particular, the controlled polymerization of N-(2-hydroxypropyl) methacrylamide (HPMA), sulfobetaine methacrylate (SBMA), phosphorylcholine methacrylate (PCMA), and carboxybetaine methacrylamide (CBMAA) was reported for the first time. The living nature of the polymerization was confirmed by a linear increase in polymer thickness over time, successful reinitiation of polymer chains, and the formation of a diblock copolymer. Furthermore, the ability to pattern surfaces using light was evaluated by restricting the irradiation area with a shadow mask. Alongside the development of surface-initiated polymerization techniques, I explored the application of polymer brushes for the preparation of functional antifouling coatings. The focus was to develop brush-coated microparticles designed to scavenge lipopolysaccharides (LPS) from blood plasma. As an endotoxin present in the outer membrane of Gram-negative bacteria, LPS can trigger severe immune responses that may lead to sepsis and inflammatory reactions, making its removal from the bloodstream critical. Polymer brushes composed of (poly(HPMA-co-CBMAA) were grafted onto poly(glycidyl methacrylate) microparticles and functionalized with polymyxin B (PMB), an antibiotic that specifically targets and neutralizes LPS. This study demonstrated the feasibility of producing functional microparticles using a minimal amount of catalyst, while effectively scavenging endotoxins from blood plasma. Additionally, a smaller section of this thesis explores the use of polymer brushes in developing affinity biosensors for targeted analyte quantification and microarrays for the selective capture of macrophages. This thesis concludes with the development of a Kill </td><td width="150">
%X  Repel coating that not only prevents protein and cell adhesion but also kills bacteria upon direct contact. This innovative strategy combines the antifouling properties of polymer brushes with the bactericidal effects of antimicrobial peptides. Hierarchical polymer brushes, featuring an antifouling base layer and a functional top layer, were functionalized with the synthetic antimicrobial peptide Pep19-2.5 as the active agent. Pep19-2.5 demonstrated high efficacy in inhibiting Staphylococcus aureus biofilm formation while maintaining compatibility with human cells. Additionally, an alternative approach was investigated, using ultra-thin surface-attached hydrogel coatings as a platform for Kill </td><td width="150">
%X  Repel applications instead of polymer brushes. In summary, this thesis presents a comprehensive approach to overcoming the challenges of protein fouling and bacterial colonization on medical devices. Through the development of a robust SET-LRP protocol and the creation of advanced polymer brush coatings, this work lays the foundation for more effective and versatile antifouling technologies, with applications ranging from biosensors and drug delivery systems to implantable medical devices.
%F PUB:(DE-HGF)11
%9 Dissertation / PhD Thesis
%R 10.18154/RWTH-2025-01441
%U https://publications.rwth-aachen.de/record/1004444