Rapid and persistent bactericidal cotton fabrics finished facilely with reactive N-halamine

Cotton fabrics (CFs) with persistent and rapid bactericidal capability would be of great significance for daily health protection because CFs are very suitable for the growth and reproduction of microorganisms. Herein, we developed a reactive N-halamine compound, 3-(3-hydroxypropyl diisocyanate)-5,5-dimethylhydantoin (IPDMH), that can be covalently bound to a CF to generate a bactericidal CF after chlorination (CF-DMF-Cl) without damaging its surface morphology. The antibacterial rates of CF-DMF-Cl (0.5 wt% IPDMH) against the gram-negative bacterium Escherichia coli (E. coli) and gram-positive bacterium Staphylococcus aureus (S. aureus) reached 99.99 % and were maintained at 90 % (against E. coli) and 93.5 % (against S. aureus) after 50 laundering cycles. The combination of contact killing and release killing mechanisms by CF-PDM-Cl leads to its rapid and persistent bactericidal activity. In addition, CF-DMF-Cl exhibits adequate biocompatibility, well-maintained mechanical properties, air/water vapor permeability and whiteness. Therefore, the proposed CF-DMF-Cl has great potential applications as a bactericidal CF for use in medical textiles, sportswear, home dressings, and so on.

N-halamine surface coating for mitigation of biofilm and microbial contamination in water systems for space travel

A copolymer termed HASL produced from monomeric units of 2-acrylamido-2-methyl-1-(5-methylhydantoinyl)propane (HA) and of 3-(trimethoxysilyl)propyl methacrylate (SL) has been coated onto stainless steel and Inconel™ substrates, which upon halogenation with either aqueous oxidative chlorine or bromine, became antimicrobial. It has been demonstrated that the halogenated stainless steel and Inconel™ substrates were effective in producing 6 to 7 log inactivations of Staphylococcus aureus and Escherichia coli O157:H7 within about 10 min, and in prevention of Pseudomonas aeruginosa biofilm formation over a period of at least 72 h on the stainless steel substrates. Upon loss of halogen, the HASL coating could be re-charged with aqueous halogen. The HASL coating was easily applied to the substrates via a simple dip-coating method and was reasonably stable to contact with water. Both chlorinated substrates could be loaded with at least 6 × 1016 oxidative Cl atoms per cm2 and maintained a loading of greater than 1 × 1016 chlorine atoms per cm2 for a period of 3-7 days while agitated in aqueous solution. After loss of chlorine to a level below 1 × 1016 atoms per cm2, the substrates could be recharged to the 6 × 1016 Cl atoms per cm2 level for at least 5 times over a 28 day period. The new antimicrobial coating technology has potential for use in a variety of important applications, particularly for water treatment and storage on spacecraft.

Reactions of phenolic compounds with monomeric N-halamines and mesoporous material-supported N-halamines

The reactions of a monomeric N-halamine, 1-chloro-5,5-dimethylhydantoin (MCDMH), and a mesoporous material-supported N-halamine (MMSNs) with phenol and p-cresol (two common contaminants in water) were investigated. MCDMH reacted rapidly with the phenolic compounds, and pH values had little effects on the reactions. On the contrary, MMSNs reacted with phenol and p-cresol only when the pH values were higher than 10. Phenol showed a lower reaction rate than p-cresol toward MMSNs. GCMS analysis suggested that MMSNs might react with the phenolic compounds through step-wise electrophilic chlorination reactions, and the main product was 2,4,6-trichlorophenol. The reaction kinetics were studied by following the disappearance of phenolic UV absorption bands, and the kinetic parameters were determined.

Antimicrobial Activity of N-Halamine-Coated Materials in Broiler Chicken Houses

The antimicrobial activity of 1-chloro-2,2,5,5-tetramethyl-4-imidazoidinone (MC), a nonbleaching N-halamine compound, was investigated on materials commonly used in broiler production, including stainless steel, galvanized metal, aluminum, plastic, and pressure-treated wood. MC aqueous solutions at 0.02, 0.04, and 0.06% were challenged with Salmonella Typhimurium and Campylobacter jejuni at 6 log CFU/mL, resulting in complete inactivation of both bacteria in 30 min with 0.06% MC. Follow-up experiments were performed using test materials treated with 0.1 and 1% MC and challenged with Salmonella Typhimurium and C. jejuni at 6 log CFU per coupon. Stability of MC on the various surfaces of testing materials was assessed, and the chlorine content of the materials was measured using iodometric thiosulfate titration over a 4-week period. Antimicrobial activities were evaluated by a sandwich test on each sampling day during 4 weeks of storage. On the samples treated with 1% MC, bacteria at 6 log CFU per coupon were completely inactivated within 2 h of contact time. The antimicrobial activity extended to 4 weeks, and the active chlorine atoms in the treated materials decreased from the initial 10¹⁶ to 10¹⁵ atoms per cm². Overall, MC had high stability and long-lasting antimicrobial activity, which suggests that MC has high potential for use as a novel antimicrobial agent to lower the microbial load on broiler house materials.