Molecular Bioengineering

Preparation and Characterization of N-Halamine-based Antimicrobial Fillers

The purpose of this study was to demonstrate that the surface of CaCO(3) fillers could be coated with an N-halamine based fatty acid to make the filler surface organophilic and accomplish antibacterial activity simultaneously, rendering the resulting polymer-filler composites antimicrobial. Thus, a new bi-functional compound, 4, 4 -Dimethyl hydantoin-undecanoic acid (DMH-UA), was synthesized by treating the potassium salt of dimethyl hydantoin (DMH) with 11-bromoundecanoic acid (BUA). Upon chlorination treatment with diluted bleach, DMH-UA was transformed into 3-chloro-4, 4-dimethyl hydantoin- undecanoic acid (Cl-DMH-UA). Alternatively, DMH-UA could be coated onto the surface of CaCO(3) to obtain the corresponding calcium salt, 4, 4-dimethyl hydantoin-undecanoic acid-calcium carbonate (DMH-UA-CaCO(3)). In the presence of diluted chlorine bleach, the coated DMH-UA on the surface of CaCO(3) was transformed into Cl-DMH-UA, leading to the formation of Cl-DMH-UA-CaCO(3). The reactions were characterized with FT-IR, NMR, UV, DSC and SEM analyses. Both Cl-DMH-UA and Cl-DMH-UA-CaCO(3) were used as antimicrobial additives for cellulose acetate (CA). The antimicrobial efficacy of the resulting samples was evaluated against both Escherichia coli (Gram-negative bacteria) and Staphylococcus aureus (Gram-positive bacteria). It was found that with the same additive content, CA samples with Cl-DMH-UA-CaCO(3) and Cl-DMH-UA had very similar antimicrobial and biofilm-controlling activity, but the former released less active chlorine into the surrounding environment than the latter.

N-Halamine-Based Antimicrobial Additives for Polymers: Preparation, Characterization and Antimicrobial Activity

A series of 3-alkyl-5,5-dimethylhydantoin derivatives were prepared by reacting 5,5-dimethylhydantoin with alkyl bromides with different alkyl chain length (C-2 to C-22). Upon chlorination, the hydration derivatives were transformed into 1-chloro-3-alkyl-5,5-dimethylhydantoins (CADMH). The structures of the samples were fully characterized with FT-IR, (1)H NMR, UV, and DSC analyses. The antimicrobial functions of CADMH were challenged with 10(8-9) CFU/mL of Escherichia coli (gram-negative bacteria) and Staphylococcus aureus (gram-positive bacteria). All the samples provided a total kill of the gram-negative and gram-positive bacteria in less than 30 min. CADMH were used as antimicrobial additives for polymeric materials. It was found that the presence of as low as 1% of CADMH could provide the samples with potent antimicrobial functions. The structure-antimicrobial efficacy relationships of the CADMH were further discussed.