Impacts of non-microbial soils on polychloramide disinfectants

The presence of some nonmicrobial chemicals and surfaces, herein called soils, are known to degrade the performance of biocides, and biocidal assays often include mixtures of materials to mimic the effects of soils. We hypothesized that water-soluble anionic polychloramide biocides were less sensitive to soil interference than cationic polymeric biocides. The relationships between soil composition and antimicrobial polymer biocidal activity were compared for an anionic polychloramide, a cationic polychloramide, and a cationic poly(quater-nary ammonium) biocide. The nanoscale soil models individually investigated were polyacrylic acid (PAA), cellulose nanocrystals (CNCs), and bovine serum albumin. The low molecular weight model soils were ammo-nium chloride, glycine, and succinimide. Three types of soil impacts were identified: 1) sequestration, whereby the soil physically inhibited transport of the biocide to microbes; 2) extraction, whereby the soil reduced or extracted oxidative chlorine, decreasing or eliminating the oxidative chlorine strength; and 3) extraction whereby the biocidal activity increases in the presence of a low molecular weight chemical that carries oxidative Cl from the polymer to the microbes. PAA and CNCs inhibit cationic biocides by sequestration but have little impact on anionic polychloramide. Glycine and BSA extract oxidative chlorine, lowering the biocidal activity of the anionic and cationic polychloramides while not impacting the poly(quaternary ammonium) biocide. Finally, the presence of succinimide increased bacteria deactivation of both anionic and cationic polychloramides. We propose that succinimide extracts oxidative chlorine from the polychloramides and transports it to the bacteria.

Automated summary

The study found that water-soluble anionic polychloramide biocides were less affected by soil interference compared to cationic polymeric biocides. Certain soil components, such as polyacrylic acid and cellulose nanocrystals, inhibited the cationic biocides but had little impact on the anionic polychloramide. Glycine and bovine serum albumin reduced the biocidal activity of both anionic and cationic polychloramides by extracting oxidative chlorine, while succinimide increased bacteria deactivation by extracting oxidative chlorine from the polychloramides and transporting it to the bacteria.