Faculty of Agricultural and Food Sciences

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Browsing Faculty of Agricultural and Food Sciences by Subject "biocides"

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    Durability of amide N-chloramine biocides to ethylene oxide sterilization
    (Oxford University Press, 2012-07-01) Zhao, Nan; Logsetty, Sarvesh; Liu, Song
    The objective of this work is to study the stability of three novel topical antimicrobial dressings consisting of amide N-chloramine structures against ethylene oxide sterilization. Cotton gauze samples bonded with one of three amide N-chloramine structures were subjected to standard ethylene oxide (EtO) sterilization. The amounts of amide N-chloramine structures before and after the sterilization were quantified to indicate the stabilities of these amide N-chloramine structures to the sterilization. The samples after sterilization were challenged with a clinical isolate of healthcare-associated multidrug-resistant Escherichia coli. N-Chloramine structure converted from polymethacrylamide (dressing 2) had the highest durability (89.7% retained active chlorine) toward EtO sterilization; that from hydantoin (dressing 3; 86.3% retained active chlorine) followed; and poly(N-chloroacrylamide) (dressing 1) had the lowest (64.0% retained active chlorine). After EtO sterilization, all the samples still reduced E. coli presence at 5 minutes of contact, with dressing 2 retaining a log 6 reduction. The three tested amide N-chloramine structures could all survive EtO sterilization while retaining percentages of active chlorine ranging from 64.0 to 89.7%. Dressing 2 showed the best durability, whereas dressing 1 had the poorest durability. With the remaining amounts of amide N-chloramine structures after EtO sterilization, all the dressings could still reduce E. coli numbers within 5 minutes of contact, and dressing 2 resulted in a log 6 reduction in colony count.
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    New Biocide with Both N -Chloramine and Quaternary Ammonium Moieties Exerts Enhanced Bactericidal Activity
    (Wiley, 2012-07-03) Li, Lingdong; Pu, Tianyun; Zhanel, George; Zhao, Nan; Ens, Werner; Liu, Song
    Considering the rise of antibiotic resistance, the development of new antibacterial agents with improved biocidal functions is urgently required. In this study, ionic 5,5-dimethylhydantoin (DMH) analogues containing either a quaternary ammonium moiety (2)–4) or a phosphonate functional group (5),–6), were designed and synthesized to investigate the possible enhancing effect of quaternary ammonium moieties on the antibacterial performance of N -chloramines. These ionic DMH analogues were converted to their N- chloramine counterparts either in free form or after being covalently immobilized on a polymer surface via the “click” chemistry method. In the subsequent antimicrobial assessment against multi-drug-resistant Escherichia coli (MDRE. coli ) and methicillin-resistant Staphylococcus aureus (MRSA), chlorinated 2 and 3, the cyclic N -chloramines with a structural cation, exhibited distinctly enhanced biocidal functions in solution and after immobilization on surfaces.