Antibacterial polymers for biofilm removal
Loading...
Authors
Lou, Yang
Issue Date
2025-08
Type
Electronic thesis
Thesis
Thesis
Language
en_US
Keywords
Materials engineering
Alternative Title
Abstract
Antibiotic-resistant infections have been rising with the abuse of antibiotics, while the number of new antibiotic drug approvals is declining. Bacterial-resistance-related infections are undermining public health and should obtain more attention. Host Defense Peptides (HDPs), also known as antibacterial peptides, are the solution of nature against bacterial infections. HDPs are amphiphilic small peptides, mostly with fewer than 50 amino acids and positive charges at physiological pH. They are antibacterial while not prone to induce resistance. Due to the instability of peptides, and the difficulty and high cost in chemical synthesis, more efforts were made to the synthesis of polymeric HDP mimics. Over the last decades, the design and synthesis of antibacterial polymers have been well researched on the control over their structural parameters – like hydrophobicity/ hydrophilicity balance, cationicity, molecular weight, functional groups, degree of polymerization, and chain length. These HDP-mimetic antibacterial polymers showed broad-spectrum antibacterial activity and low toxicity toward mammalian cells. The performance of antimicrobial polymers depends sensitively on the cationic species, charge density, and spatial arrangement of cations. Chapter 2 introduced the first example of antimicrobial polymers bearing bulky tetraaminophosphonium groups as the source of highly delocalized cationic charge. The bulky cations drastically enhanced the biocidal activity of amphiphilic polymers, leading to potent activity in the sub-micromolar range. In this work, we reveal for the first time that bulky phosphonium cations are associated with markedly enhanced biocidal activity, which provides a new strategy to develop more effective self-disinfecting materials.
The above-mentioned research from Chapter 2 focuses on killing bacteria in solution with antibacterial polymers. Polymers can also be processed into coatings for antibacterial surfaces, capable of killing bacteria upon contact. Nonetheless, it is imperative to acknowledge that any antibacterial surface will inevitably encounter issues with biofilm accumulation which are intricate assemblies of microorganisms embedded within crosslinked polymer structures built by microorganisms. In Chapter 3, we develop a simple, dynamically reversible method of polymer surface coating that enables both chemical killing on-contact, as well as on-demand mechanical delamination of surface-bound biofilms by triggered depolymerization of the underlying antimicrobial coating layer. This work provides a new and simple strategy for antimicrobial coatings that can kill bacteria on-contact for extended timescales, followed by triggered biofilm removal under mild conditions.
A notable drawback of degradable poly(disulfide) antibacterial coatings lies in the complete loss of functionality following triggered degradation. In order to enhance the practical utility of these coatings, the incorporation of surface-regenerating capabilities emerges as a pivotal strategy for considerably prolonging the surface lifespan. In Chapter 4, I introduced the study of poly(disulfide)s thermosets with azo-containing crosslinkers as potential material candidates for applications in renewable antibacterial/antifouling polymer coatings. At the decomposition temperature of the azo groups, the crosslinkers break down, leading to network decrosslinking and the generation of radicals that initiate degradation of the poly(disulfide) backbones. These materials enable heat-triggered degradation and the potential for surface regeneration, paving the way for renewable antibacterial and antifouling coatings.
Description
August2025
School of Engineering
School of Engineering
Full Citation
Publisher
Rensselaer Polytechnic Institute, Troy, NY