Antimicrobial N-Halamine Polymers and Applications

Antimicrobial N-halamine polymers represent a versatile class of materials in which nitrogen centres are covalently bonded to halogen atoms, most commonly chlorine. Upon contact with microbial cells, these N–Cl bonds release oxidative chlorine species that inactivate bacteria, fungi and viruses through oxidative damage to proteins and membranes. A defining feature of N-halamine systems is their rechargeability: spent materials can be regenerated by simple exposure to dilute bleach, restoring biocidal function without leaching harmful residues. This property has spurred integration of N-halamines into diverse substrates, including textiles, nonwoven fabrics, coatings, filtration media and wound dressings. In each case, design strategies focus on optimising chlorine loading, distribution and retention under operational conditions while preserving mechanical integrity and biocompatibility. Advances in graft polymerisation, surface-initiated radical techniques and reactive extrusion have enabled covalent incorporation of N-halamine precursors onto synthetic and natural polymers alike, yielding stable, long-lasting antimicrobial interfaces. The global significance of this technology lies in its potential to curb healthcare-associated infections, improve food safety, enhance public-space sanitation and deliver self-sterilising packaging, all via scalable, cost-effective processes. Recent work has also begun to explore synergy between N-halamines and other antimicrobial motifs, such as metal nanoparticles and nanocarbon materials, pointing to next-generation multifunctional surfaces and membranes.

Research from Nature Portfolio

In a recent study, nonwoven cotton fabric was modified through alkali activation followed by dip-coating with chitosan and silver nanoparticles, and subsequently chlorinated to convert amide N–H groups into N-Cl halamine sites. The treated textile exhibited rapid and complete inactivation of both Gram-positive and Gram-negative bacteria without compromising mechanical strength. Active-chlorine measurements demonstrated stable loading, and cell viability assays confirmed low cytotoxicity toward mammalian cells. The process is economical and environmentally benign, making the material suitable for antimicrobial wipes, food-contact surfaces and biomedical dressings. Importantly, the fabric retained its biocidal efficacy over multiple laundering and rechlorination cycles, underscoring the practicality of N-halamine functionalisation for large-scale commercial use.

Antimicrobial N-Halamine Polymers and Applications publication trend

The graph below shows the total number of articles in antimicrobial n-halamine polymers and applications across all publications each year (not limited to Nature Index journals).

Technical terms

N-halamine: A functional group in which a halogen atom is covalently bound to nitrogen, capable of releasing oxidative halogen species upon contact with microbes.

Oxidative chlorine: Highly reactive chlorine species generated from N-halamine bonds that disrupt microbial biomolecules.

Chlorination: The chemical conversion of N–H sites on a polymer into N–Cl bonds by treatment with a chlorine source (e.g. sodium hypochlorite).

Electrospinning: A technique that uses an electric field to draw polymer solutions into fine fibres, producing nanofibrous mats with high surface area for functionalisation.

Graft polymerisation: A method for covalently attaching monomer chains to a polymer backbone or surface, introducing reactive or functional groups such as N-halamine precursors.

References

1. Clear polyurethane coatings with excellent virucidal properties: Preparation, characterization and rapid inactivation of human coronaviruses 229E and SARS-CoV-2. Applied Materials Today (2023).
2. N-Halamine Biocidal Materials with Superior Antimicrobial Efficacies for Wound Dressings. Molecules (2017).
3. Cost-effective fabrication, antibacterial application and cell viability studies of modified nonwoven cotton fabric. Scientific Reports (2022).
4. An N-Halamine/Graphene Oxide-Functionalized Electrospun Polymer Membrane That Inactivates Bacteria on Contact and by Releasing Active Chlorine. Polymers (2021).
5. Fabrication of Polypropylene‐g‐(Diallylamino Triazine) Bifunctional Nonwovens with Antibacterial and Air Filtration Activities by Reactive Extrusion and Melt‐Blown Technology. Journal of Chemistry (2019).