Controlling the Structure and Antimicrobial Function of N-Halamine-Based Polyurethane Semi-interpenetrating Polymer Networks

Nonleaching Biocidal N-Halamine-Functionalized Polyamine-, Guanidine-, and Hydantoin-Based Coatings

Fibrous materials with inherent antimicrobial properties can help in real-time deactivation of microorganisms, enabling multiple uses while reducing secondary infections. Coatings with antiviral polymers enhance the surface functionality for existing and potential future pandemics. Herein, we demonstrated a straightforward route toward biocidal surface creation using polymers with nucleophilic biguanide, guanidine, and hydantoin groups that are covalently attached onto a solid support. Biocidal poly(N-vinylguanidine) (PVG) and poly(allylamine-co-4-aminopyridine-co-5-(4-hydroxybenzylidene)hydantoin) (PAH) were introduced for coating applications along with commercially available polyvinylamine (PVAm) and poly(hexamethylene biguanide) (PHMB). Nonleaching coatings were created by first fabricating bifunctional siloxane or isocyanate precursor coatings on the cotton, nylon-cotton, and glass fiber fabric, followed by the polymer attachment. The developed grafting methods ensured the stability of the coating and the reuse of the material while maintaining the biocidal properties. Halogenation of polymer-coated fabric was conducted by aqueous solutions of sodium hypochlorite or in situ generation of hypobromous acid (HOBr), resulting in surfaces coated by N-halamines with high contents of active > N-Cl or > N-Br groups. The polymer-coated fabrics were stable in multiple laundry cycles and maintained hydrophilic character after coating and halogenation. Halogenated polymer-coated fabrics completely inactivated human respiratory coronavirus based on a contact-killing mechanism and were shown to be reusable after recharging with bromine or chlorine.

Surface Modification of Polyurethane Membrane with Various Hydrophilic Monomers and N-Halamine: Surface Characterization and Antimicrobial Properties Evaluation

Reducing microbial infections associated with biomedical devices or articles/furniture noted in a hospital or outpatient clinic remains a great challenge to researchers. Due to its stability and low toxicity, the N-halamine compound has been proposed as a potential antimicrobial agent. It can be incorporated into or blended with the FDA-approved biomaterials. Surface grafting or coating of N-halamine was also reported. Nevertheless, the hydrophobic nature associated with its chemical configuration may affect the microbial interactions with the chlorinated N-halamine-containing substrate. In this study, a polymerizable N-halamine compound was synthesized and grafted onto a polyurethane surface via a surface-initiated atom transfer radical polymerization (SI-ATRP) scheme. Further, using the sequential SI-ATRP reaction method, different hydrophilic monomers, namely poly (ethylene glycol) methacrylate (PEGMA), hydroxyethyl methacrylate (HEMA), and [2-(methacryloyloxy) ethyl] dimethyl-(3-sulfopropyl) ammonium hydroxide (SBMA), were also grafted onto the polyurethane (PU) substrate before the N-halamine grafting reaction to change the surface properties of the N-halamine-modified substrate. It was noted that the chains containing the hydrophilic monomer and the polymerizable N-halamine compound were successfully grafted onto the PU substrate. The degree of chlorination was improved with the introduction of a hydrophilic monomer, except the HEMA. All of these hydrophilic monomer-containing N-halamine-modified PU substrates demonstrated a more than 2 log CFU reduction after microbial incubation. In contrast, the surface modified with N-halamine only exhibited significantly less antimicrobial efficacy instead. This is likely due to the synergistic effects caused by the reduced chlorine content, as well as the reduced surface interactions with the microbes.

Fabrication of N-halamine polyurethane films with excellent antibacterial properties

An N-halamine precursor, namely, 2-amino-5-(2-hydroxyethyl)-6-methylpyrimidin-4-one (AHM), was used as a chain extender in the preparation of a series of N-halamine polyurethane (PU) films, in order to also instill antibacterial properties. The mechanical properties, thermodynamic performance, and antimicrobial performance of the functionalized PU films were systematically studied. The results showed that the addition of AHM could improve the thermodynamic and mechanical properties of the developed PU films. Conducting tests in the presence of Escherichia coli and Staphylococcus aureus as the model microorganisms revealed that prior to chlorination the antibacterial properties of the chlorinated PU-AHM-Cl films improved significantly relative to the analogous films. The excellent antibacterial properties and the overall superior performance of the PU-AHM-Cl films allow their potential application in microbiological protection materials and related fields.

Functional-modified polyurethanes for rendering surfaces antimicrobial: An overview

Antimicrobial surfaces and coatings are rapidly emerging as primary components in functional modification of materials and play an important role in addressing the problems associated with biofouling and microbial infection. Polyurethane (PU) consisting of alternating soft and hard segments has been one of the most important coating materials that have been widely applied in many fields due to its versatile properties. This review attempts to provide insight into the recent advances in antimicrobial polyurethane coatings or surfaces. According to different classes of antimicrobial components along with their antimicrobial mechanism, the synthesis pathways are presented systematically herein to afford polyurethane with antimicrobial properties. Also, the challenges and opportunities of antimicrobial PU coatings and surfaces are also discussed. This review will be beneficial to the exploitation and the further studies of antimicrobial polyurethane materials for a variety of applications.

Nanolayers of Poly(N,N'-Dimethylaminoethyl Methacrylate) with a Star Topology and Their Antibacterial Activity

In this paper, we focus on the synthesis and characterization of novel stable nanolayers made of star methacrylate polymers. The effect of nanolayer modification on its antibacterial properties was also studied. A covalent immobilization of star poly(N,N'-dimethylaminoethyl methacrylate) (PDMAEMA) to benzophenone functionalized glass or silicon supports was carried out via a "grafting to" approach using UV irradiation. To date, star polymer UV immobilization has never been used for this purpose. The thickness of the resulting nanolayers increased from 30 to 120 nm with the molar mass of the immobilized stars. The successful bonding of star PDMAEMA to the supports was confirmed by surface sensitive quantitative spectroscopic methods. Next, amino groups in the polymer layer were quaternized with bromoethane, and the influence of this modification on the antibacterial properties of the obtained materials was analyzed using a selected reference strain of bacteria. The resulting star nanolayer surfaces exhibited higher antimicrobial activity against Bacillus subtilis ATCC 6633 compared to that of the linear PDMAEMA analogues grafted onto a support. These promising results and the knowledge about the influence of the topology and modification of PDMAEMA layers on their properties may help in searching for new materials for antimicrobial applications in medicine.

Synthesis of sulfonium N-chloramines for antibacterial applications

Sulfonium N-chloramines were synthesized with significantly higher antibacterial efficacy than previous quaternary ammonium counterpart 1, and the highest efficacy was achieved for dodecyl chained N-chloramine 9 due to a synergistic biocidal effect.

Synthesis and polymerization of a new hydantoin monomer with three halogen binding sites for developing highly antibacterial surfaces

Novel three halogen capturing hydantoin monomer-based copolymers were synthesized and evaluated for their antibacterial properties.