Hypochlorite activated poly(N-isopropylacrylamide)-core poly(N-isopropylmethacrylamide)-shell microgels—An oxidant with the potential to kill cells

Low Molecular Weight Shuttle Molecules Enhance Polychloramide Antimicrobial Activity

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.

N-halamine modified multiporous bacterial cellulose with enhanced antibacterial and hemostatic properties

Bacterial cellulose (BC) is a natural polymer with remarkable superiority for fabricating biomaterials. In this study, a multiporous bacterial cellulose (MBC) film was modified with N-isopropylacrylamide (NIPAM), and the modified MBC film was imbued with antibacterial properties after chlorination. The dried chlorinated samples showed superb antibacterial efficacy and could inactivate 6.19 log of inoculated S. aureus and 6.29 log of E. coli within 1 min of contact. After releasing active chlorine for 12 h, 3.67 log of S. aureus and 3.97 log of E. coli were inactivated within 30 min of contact. The prepared films displayed high porous and layered structures with a resultant excellent water retention which can be applied as material for wound dressings. In addition, the chlorinated films showed hemostatic ability on wound bleeding and good biocompatibility. The prepared N-halamine functionalized MBC films might have great potential applications as wound dressings.