Due to the emergence of wide-spread infectious diseases, there is a heightened need for antimicrobial and/or antifouling coatings that can be used to prevent infection and transmission in a variety of applications, ranging from healthcare devices to public facilities. While antimicrobial coatings kill pathogenic bacteria upon contact with the surface, the antimicrobial function alone often lacks long-term effectiveness due to the accumulation of dead cells and their debris on the surface, thus reducing the performance of the coating over time. Therefore, it is desirable to develop coatings with the dual functions of antimicrobial efficacy and fouling resistance, in which antifouling coatings provide the added benefit of preventing the adhesion of dead cells and debris. Leveraging the outstanding antifouling properties of zwitterionic coatings, we synthesized copolymers with this antimicrobial-antifouling dual function by immobilizing lysozyme, a common antimicrobial enzyme, to the surface of a pyridinium-based zwitterionic copolymer. Specifically, poly(4-vinylpyridine- co -pentaflurophenyl methacrylate- co -divinyl benzene) [P(4VP-PFPMA-DVB)] thin films were synthesized by an all-dry vapor deposition technique, initiated Chemical Vapor Deposition, and derivatized using 1,3-propane sultone to obtain sulfobetaine moieties. Lysozyme, known to hydrolyze polysaccharides in the cell wall of Gram-positive bacteria, was immobilized by forming amide bonds with the copolymer coating via nucleophilic substitution of the pentafluorophenyl group. The antifouling and antibacterial performance of the novel lysozyme-zwitterionic coating was tested against Gram-positive Bacillus subtilis and Gram-negative Pseudomonas aeruginosa . A reduction in surface adhesion of 87% was achieved for P. aeruginosa , and of 75% for B. subtilis , when compared to a common poly(vinyl chloride) surface. The lysozyme-zwitterionic coating also deactivated 67% of surface-attached Gram-positive bacteria, B. subtilis . This novel dual-function material can produce anti -infection surfaces for medical devices and surgical tools, personal care products, and surfaces in public facilities.
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Antifouling Coatings from Glassy Polyelectrolyte Complex Films
Coatings that prevent or decrease fouling are sought for many applications, including those that inhibit the attachment of organisms in aquatic environments. To date, antifouling coatings have mostly followed design criteria assembled over decades: surfaces should be well/strongly hydrated, possess low net charge and maintain a hydrophilic character when exposed to the location of use. Thus, polymers based on ethylene glycol or zwitterionic repeat units have been shown to be highly effective. Unfortunately, hydrated materials can be quite soft, limiting their use in some environments. In a major paradigm shift, this work describes glassy antifouling films made from certain complexes of positive and negative polyelectrolytes. The dense network of electrostatic interactions yields tough materials below the glass transition temperature, Tg, in normal use, while the highly ionic character of these polyelectrolyte complexes ensures strong hydration. The close proximity of equal numbers of opposite charges within these complexes mimics zwitterionic structures. Films, assembled layer-by-layer from aqueous solutions, contained sulfonated poly(ether ether ketone), SPEEK, a rigid polyelectrolyte which binds strongly to a selection of quaternary ammonium polycations. Layer-by-layer buildup of SPEEK and polycations was linear, indicating strong complexes between polyelectrolytes. Calorimetry also showed complex formation was exothermic. Surfaces coated with these films in the 100 nm thickness range completely resisted adhesion of the common flagellate green algae, Chlamydomonas reinhardtii which were removed from surfaces at the minimum applied flow rate of 0.8 cm s-1. The total surface charge density of adsorbed cations, determined with a sensitive radioisotopic label, was very low, around 10% of a monolayer, which minimized adsorption driven by counterion release from the surface. The viscoelastic properties of the complexes, which were stable even in concentrated salt solutions, were explored using rheology of bulk samples. When fully hydrated, their Tgs were observed to be above 75 oC.
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- Award ID(s):
- 2103703
- PAR ID:
- 10518756
- Publisher / Repository:
- American Chemical Society
- Date Published:
- Journal Name:
- ACS Applied Materials & Interfaces
- Volume:
- 15
- Issue:
- 43
- ISSN:
- 1944-8244
- Page Range / eLocation ID:
- 50058 to 50068
- Format(s):
- Medium: X
- Sponsoring Org:
- National Science Foundation
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Abstract Zwitterionic surfaces are increasingly explored as antifouling coatings due to their propensity to resist protein, bacterial, and cell adhesion and are typically applied as polymeric systems. Here, the self‐assembly of strongly interacting small molecule amphiphiles is reported to produce nanoribbons for antifouling applications. Synthesized amphiphiles spontaneously form micrometers‐long nanoribbons with nanometer‐scale cross‐sections and intrinsically display a dense coating of zwitterionic moieties on their surfaces. Substrates coated with nanoribbons demonstrate concentration‐dependent thicknesses and near superhydrophilicity. These surface coatings are then probed for antifouling properties and substantial reductions are demonstrated in protein adsorption, bacterial biofilm formation, and cell adhesion relative to uncoated controls. Harnessing cohesive small molecule self‐assembling nanomaterials for surface coatings offers a facile route to effective antifouling surfaces.
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Direct layer-by-layer (LbL) assembly of cationic, small-molecule antibacterial bioactives with water-soluble, ionic polyphosphazenes (PPzs) containing trifluoroethoxy and carboxy substitients is reported. First, influence of PPzs hydrophobicity and antibiotic charge density on LbL assembly was studied via evolution of dry film thickness. We found that the use of fluorinated PPz polyelectrolytes enhanced ionic pairing within LbL coatings, and that increasing charge density of small molecules increased antibiotic uptake. This strategy was successful even in the case of gentamicin, a hydrophilic, small antibiotic with only 3 to 4 positive charges at pH 7.5. Confirmation of antibiotic presence in films was demonstrated via x-ray photoelectron spectroscopy. Importantly, LbL films of fluorinated PPz polyelectrolytes retained antibiotics in physiological conditions due to the enhanced hydrophobic interactions. In contrast, LbL films of non-fluorinated PPzs released antibiotics at low pH and in the presence of salt following the charge renormalization argument. The potential of these coatings with a biomedically relevant bacterial strain, Staphylococcus aureus, is discussed.more » « less
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Abstract Demand for long‐lasting antifouling surfaces has steered the development of accessible, novel, biocompatible and environmentally friendly materials. Inspired by lubricin (LUB), a component of mammalian synovial fluid with excellent antifouling properties, three block polymers offering stability, efficacy, and ease of use were designed. The bottlebrush‐structured polymers adsorbed strongly on silica surfaces in less than 10 minutes by a simple drop casting or online exposure method and were extremely stable in high‐salinity solutions and across a wide pH range. Antifouling properties against proteins and bacteria were evaluated with different techniques and ultralow fouling properties demonstrated. With serum albumin and lysozyme adsorption <0.2 ng cm−2, the polymers were 50 and 25 times more effective than LUB and known ultralow fouling coatings. The antifouling properties were also tested under MPa compression pressures by direct force measurements using surface forces apparatus. The findings suggest that these polymers are among the most robust and efficient antifouling agents currently known.
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Abstract Demand for long‐lasting antifouling surfaces has steered the development of accessible, novel, biocompatible and environmentally friendly materials. Inspired by lubricin (LUB), a component of mammalian synovial fluid with excellent antifouling properties, three block polymers offering stability, efficacy, and ease of use were designed. The bottlebrush‐structured polymers adsorbed strongly on silica surfaces in less than 10 minutes by a simple drop casting or online exposure method and were extremely stable in high‐salinity solutions and across a wide pH range. Antifouling properties against proteins and bacteria were evaluated with different techniques and ultralow fouling properties demonstrated. With serum albumin and lysozyme adsorption <0.2 ng cm−2, the polymers were 50 and 25 times more effective than LUB and known ultralow fouling coatings. The antifouling properties were also tested under MPa compression pressures by direct force measurements using surface forces apparatus. The findings suggest that these polymers are among the most robust and efficient antifouling agents currently known.
- Free Publicly Accessible Full Text
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Accepted Manuscript1.0
- Journal Article:
- https://doi.org/10.1021/acsami.3c11744
