posted on 2023-12-11, 23:43authored byGaoyin He, Lei Tian, Jun Liu, Michael Fefer, Zeinab Hosseinidoust, Robert H. Pelton
Investigated
were the influences of succinimide (SI), 5,5-dimethylhydantoin
(DMH), and 3-(hydroxymethyl)-5,5-dimethylhydantoin (HDMH)
on the biocidal activity of chlorinated, water-soluble polyamide prepared
by the reaction of isopropylamine with poly(styrene-alt-maleic anhydride). The resulting polymer was a negatively charged,
water-soluble polymer bearing a carboxylic acid and an isopropylamide
moiety on nearly every repeat unit. Subsequent treatment with NaOCl
chlorinated the polymers to up to 4.4% Cl while inflicting some polymer
chain scission. SI, DMH, or HDMH increased the biocidal activity of
polychloramides toward planktonic Escherichia coli and Staphylococcus aureus. Independent
solution studies confirmed that oxidative chlorine spontaneously transferred
from aqueous polychloramides to small molecules. We concluded that
SI, DMH, and HDMH acted as shuttles that extracted oxidative Cl from
the polymer chloramides and transported oxidative Cl more efficiently
to microbial surfaces. Succinimide was the most effective shuttle.
These results warn that some low molecular weight soluble molecules
in antimicrobial testing solutions may exaggerate the effectiveness
of the polymer or immobilized antimicrobial agents.